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[Display omitted] Despite their excellent environmental stability, low defect density, and high carrier mobility, large- n quasi-two-dimensional halide perovskites (quasi-2DHPs) feature a limited application scope because of the formation of self-assembled multiple quantum wells (QWs) due to the similar thermal stabilities of large- n phases. However, large- n quasi-phase-pure 2DHPs (quasi-PP-2DHPs) can solve this problem perfectly. This review discusses the structures, formation mechanisms, and photoelectronic and physical properties of quasi-PP-2DHPs, summarises the corresponding single crystals, thin films, and heterojunction preparation methods, and presents the related advances. Moreover, we focus on applications of large- n quasi-PP-2DHPs in solar cells, photodetectors, lasers, light-emitting diodes, and field-effect transistors, discuss the challenges and prospects of these emerging photoelectronic materials, and review the potential technological developments in this area. [ABSTRACT FROM AUTHOR]

Molecular hydrogen (H 2) is one of the future energy carriers when replacing fossil sources. Enzymatic systems serve as an inspiration for the design of novel hydrogen evolving catalysts. Though several heterobimetallic Ru systems are known as catalysts for the hydrogen evolution reaction (HER), homogeneous mononuclear Ru systems have not been explored much. Here, a new mononuclear Ru(II) complex [ cis -RuCl 2 (PPh 3) 2 (κ 2- TL)] (TL = 2-thiophenyl benzimidazole) possessing distorted octahedral geometry, has been synthesised and characterized as an efficient catalyst for acid-assisted hydrogen evolution by using various spectroscopic techniques as well as quantum chemical calculations. When trifluoroacetic acid is used as the proton source, the complex shows remarkable catalytic activity towards H 2 production. Based on the DFT calculations, an EECC mechanism could be proposed for HER, consistent with the assignment of the observed redox transitions. • Interdisciplinary research on energy and environmental catalysis is required to develop renewable sources of energy. • Hydrogen has emerged as an alternative energy carrier due to its carbon-free burning. • Enzymatic systems serve as an inspiration for the design of novel hydrogen evolving catalysts. • Very few bio-inspired homogeneous mononuclear Ru mimics have been explored as HER electrocatalysts. • The reported work reveals design principles for future HER catalysts that can operate at ambient conditions. [ABSTRACT FROM AUTHOR]

We review the present status of gauge theories built on various quantum space–times described by noncommutative space–times. The mathematical tools and notions underlying their construction are given. Different formulations of gauge theory models on Moyal spaces as well as on quantum spaces whose coordinates form a Lie algebra are covered, with particular emphasis on some explored quantum properties. Recent attempts aiming to include gravity dynamics within a noncommutative framework are also considered. [ABSTRACT FROM AUTHOR]

A nonplanar a-plane (11–20) and c-plane (0001) InGaN/GaN multiple quantum wells (MQWs) structures were grown an r-plane (1–102) and a c-plane (0001) sapphire (Al 2 O 3) substrate, respectively. Using two-dimensional confocal photoluminescence spectroscopy, the spatially resolved optical characteristics of two samples are examined. We found that the integrated PL intensity of a-plane MQWs is 88.4% greater than that of c-plane MQWs based on our analysis of PL spectra taken at room temperature. According to results from two-dimensional confocal PL mapping, the a-plane MQWs have a more uniform distribution of PL intensity according to two-dimensional space than the c-plane MQWs. Compared to typical c-plane InGaN/GaN MQWs, the experimental results of the two-dimensional confocal PL peak position distribution and PL spectrum skewness map of nonpolar a-plane InGaN/GaN MQWs show increased uniformity of the InGaN alloy in two-dimensional space and a decreased proportion of multiple PL peaks buried in the PL spectrum. These findings are ascribed to higher electron and hole wavefunction overlap caused by decreased the quantum-confinement Stark effect and increased the uniformity of InGaN alloy in the two-dimensional space of nonpolar a-plane InGaN QW. [ABSTRACT FROM AUTHOR]

• The current density is improved by incorporating the type-A InP QW in the top cell. • Carrier transport through the tunnel oxide region is enhanced by lowering down the thickness to the nanoscale. • The GaInP/Si integrated model achieves efficiency of 33.30 % for 7 QWs incorporation in the top cell. • With combination of both QWs and TOPCon technology, model achieves efficiency of 41.95 % for 0.2 nm thickness of SiO 2. • This model advances toward achieving the 45 % efficiency limit of III-V/Si 2-junction 2-terminal solar cell. The GaInP/Si dual junction solar cell with Quantum Well and TOPCon technology has achieved 41.91 % efficiency in the simulation model. Quantum wells are proven to enhance the short circuit current without any significant degradation of open circuit voltage. The voltage preservation measure (for minimum reduction in open circuit voltage) is applied in design of Quantum well solar cell with the improvement in short circuit current, therefore the overall efficiency of dual junction cell is enhanced. In this work, the GaInP/Si dual junction solar cell is proposed by incorporating the InP quantum wells in the p-i-n region of GaInP top cell. Also, the TOPCon technology is applied at the rear side of the bottom c-Si solar cell. The quantum well increases the absorption of sub-bandgap photon energy. The buffer layer reduces the misfits between the lattice mismatched layers and tunnel oxide provides excellent passivation mechanism to increase the open circuit voltage. The ultrathin oxide layer provides extremely high electric field as described by the MIS tunneling theory. The electron and hole bound state energy and wavefunctions provides "miniband" formation and charge carrier trapping. The formation of type-A band structure in quantum well region and excellent electron mobility results in enhanced carrier transport. The GaInP/Si integrated model achieves efficiency of 33.30 % when the quantum wells are incorporated in the top cell. When the Combination of both QWs (in top cell) and TOPCon technology (in bottom cell) is applied, the model achieves 41.95 % efficiency. This model provides an excellent route toward achieving the 45 % efficiency limit of III-V/Si dual junction 2-terminal solar cell. The industry standard Silvaco TCAD platform is used for the calculation of the performance characteristics in AM1.5G environmental condition. [ABSTRACT FROM AUTHOR]

Lithium-sulfur (Li-S) batteries boast a multitude of compelling attributes, chief among them being their exceptional energy density and relatively low raw material costs. However, the sluggish redox kinetics of sulfur stemming from the considerable desolvation energy barrier and the notorious shuttle effect of lithium polysulfides, pose significant challenges in the commercialization of Li-S batteries. In this work, ultra-fine WB quantum dots were in-situ and uniformly dispersed on reduced graphene oxide nanosheets (WB-rGO) by mild melting-salt method, in which the abundant oxygen-containing functional groups in graphene oxide effectively prevent the agglomeration of WB. Such ultra-fine WB quantum dot as well as dual-active sites stemming from W and electronics-deficient B, confer the WB-rGO composite with improved electrochemical active surface area for dissociating Li+-solvents molecules and catalyzing polysulfides transformations, thus improving cycling and rate performance of Li-S battery. Hence, the cells with WB-rGO@PP maintained a stable long-term cycling (650 mAh g−1 after 900 cycles at 1 C with an average decay rate of 0.038 % per cycle) and an impressive rate capability (740 mAh g−1 at 4 C). Even at a sulfur loading of 4.7 mg cm−2, the cell performed a high areal capacity of 3.6 mAh cm−2 after 200 cycles. [Display omitted] • Ultra-fine WB quantum dots were in-situ anchored on reduced graphene oxide by mild molten-salt method. • The WB-rGO can simultaneously accelerate the desolvation of solvated Li+ and the conversion of LiPSs. • The WB-rGO modified separator endowed sulfur cathode with excellent cycling, rate and high-loading performance. [ABSTRACT FROM AUTHOR]

InGaN-based red-emitting LEDs based on V-pits exhibit patchy electroluminescence. The V-pits in the active regions can effectively capture carriers, preventing them from migrating to the chip edges. This leads to not only very weak surface recombination effect on these devices, but also strong anti-correlation between the emission wavelength and intensity due to the reduced carrier densities in the V-pit-rich regions. [Display omitted] • Different sized InGaN red LEDs (from 500 × 500 to 15 × 15 µm2) based on V-pits were characterized systematically. • Suppressed surface recombination effect is revealed, in the light–current-voltage (LIV) measurement and electroluminescence (EL) image analysis. • The analysis on the spatially-resolved EL images show that there is a strong correlation between the wavelength and the intensity, showing that the regions with longer wavelengths have weaker intensities. • This anti-correlation can be explained by the reduced carrier injection to the flat QWs in the V-pit-rich regions due to the carrier trapping by the V-pit QWs and dislocations. InGaN-based red light-emitting diodes (LEDs) are a promising candidate to achieve high efficiency, which is highly desired by the display market. Understanding their size-dependent properties is crucial for further performance improvement. In this work, different sized InGaN red LEDs (from 500 × 500 to 15 × 15 µm2) based on V-pits were characterized systematically. The current–voltage characteristics show that the leakage current density, revealed either in forward or reverse bias, is independent of the chip size. Further light output power measurements and current dependent electroluminescence also reveal very weak dependence of the power density on chip size showing insensitivity the chip perimeter. The suppressed surface recombination effect may be due to effective carrier trapping effect by the V-pits, which prevents the carriers from flowing to the sidewalls. By detailed analysis of the spatially resolved electroluminescence, an anti-correlation between the emission wavelengths and the intensities was observed, with the longer wavelength emitting regions exhibit weaker intensity, which can be explained by the reduced carrier density in the V-pit-rich regions as carriers are partially captured by quantum wells associated with the V-pits and the associated dislocations. This study will pave the way for further understanding and improving the efficiency of InGaN red LEDs including micro-LEDs. [ABSTRACT FROM AUTHOR]

Small-molecule fluorescent ligands targeting mitochondrial G-quadruplexes (mtG4s) are considered as a promising direction in tumor therapy, especially those with dual roles of both detecting the mtG4 structures and interfering with the mtG4 functions. Herein, based on our previous studies, two novel thiophene-benzoindolium ligands (YS-1 and YS-2) were designed and synthesized. One of them, YS-2 , may be a potential NIR fluorescent probe, with an absorption band centered at 595 nm and an emission band centered at 685 nm, as well as a good quantum yield upon binding G4s. YS-2 was further proved to selectively bind to mtG4s in MDA-MB-231 cells, and then induce mitochondrial dysfunction, showing suppressive effects on the proliferation of tumor cells in both 2D and 3D cell models. To sum up, a novel highly emissive NIR ligand binding to mtG4s was successfully discovered, giving insights into the future development of novel G4 fluorescent ligands targeting mtG4s with therapeutic possibilities against tumors. • The combination of thiophene with benzoindolium gave a promising near-infrared ligand for mtG4s. • This ligand could illuminate the mtG4s, and interfere with the mitochondrial metabolism. • This ligand may induce mitochondrial dysfunction, and thereby trigger apoptosis. [ABSTRACT FROM AUTHOR]

CsPbX 3 (X = Br, Cl, and I) perovskite quantum dots (QDs) have become promising materials for phosphors and solar cells due to their remarkable photovoltaic properties. However, the high defect density and sensitivity to the surrounding environment have hindered the commercial application of the materials in the field of optoelectronics. Core-shell structures have been proved to be an effective method for passivating surface defects and improving stability. However, the complex post-processing tends to dissolve the CsPbX 3 QDs, causing the strategy to remain relatively underdeveloped. Here, we present an improved hot-injection method that can facilitate the epitaxial growth of CsPb 2 Br 5 shell on the surface of CsPbBr 3 QDs, and, by doping Sr2+ ions to passivate the defects of the QDs, CsPbBr 3 @CsPb 2 Br 5 :Sr core-shell microplates have been obtained. The composites have enhanced optical properties and stability. Density Functional Theory (DFT) calculations show that this is benefited from the introduction of Sr which widens the bandgap of CsPbBr 3 and CsPb 2 Br 5 , leading to the formation of a quantum well structure between the two, significantly improving the quantum yields of the samples. Finally, the white light emitting diodes prepared using the composite have high luminous efficiency and long-term operational stability. • CCS composites with core-shell structure were directly obtained by thermal injection method. • CCS composites reached PLQY of 96 %. • DFT calculations demonstrated that Sr2+ promoted the formation of type-I heterojunctions in CCS composites. • After 12 days of immersion in water, the PL intensity of CCS composites retained 96.8 %. • After 15 h of continuous operation at 105 °C, the PL intensity of WLED remained above 90 %. [ABSTRACT FROM AUTHOR]

The spectroscopy features of sodium alumino boro˗tellurite oxyfluoride glasses doped with various molar fractions of Eu 2 O 3 ions (TBANEu) are studied through absorbance, excitation, emission, and decay curves. The excitation data are used following phonon side band spectroscopy to evaluate the phonon energy (1326 cm-1) of the glass host. The densities, molar volumes, and refractive indices, including the Ω 2,4,6 parameters of fabricated glasses are studied. The magnitudes of laser properties like effective line widths, branching ratios, and emission cross˗sections obtained for the Eu3+:5D 0 →7F 2 transition could be useful for reddish-orange lighting devices application. Additionally the quantum efficiency estimated from experimental and calculated lifetimes is about ˃ 70% for the 5D 0 level luminescence of TBANEu glasses. Upon 395 nm radiation, the current glass system can exhibit color coordinates close to (0.647, 0.351) for reddish˗orange light as performed by the CIE1931 chromaticity diagram. The integral scintillation intensities of TBANEu glasses were determined using the X˗ray excitation and observed that the TBANEu20 glass showed a highest scintillation efficiency of 39%, resulting in scintillator and X˗ray sensing device applications. • Eu3+ -doped sodium alumino boro-tellurite oxyfluoride scintillating glasses were fabricated by the melt quenching method. • The phonon energy (1326 cm-1) of the current glass host was estimated by the phonon side band spectroscopy. • JO intensity and radiative parameters, decay times, as well as quantum efficiency of glasses were calculated. • Color coordinates, relative color temperatures, and color purity of studied glasses were also studied. • The maximum scintillation efficiency of 39% in BGO crystal was obtained under x-ray excitation. [ABSTRACT FROM AUTHOR]

The linear confinement in two-dimensions can yield an analogue of a triangular well or a quantum bouncer. We discuss a way of achieving a linear confinement of a neutral particle with a permanent magnetic dipole moment in a magnetic medium by dealing with a two-dimensional system with cylindrical symmetry. This linear confinement is characterized by being spin-dependent. Then, by including the Aharonov–Casher geometric quantum phase, we show that bound states analogous to those of the quantum bouncer can be achieved, where the energy levels are infinitely degenerated with regard to the ℓ -waves. Further, we obtain the revival time of the system. • Spin-dependent linear potential. • Analogue of the triangular well with the cylindrical symmetry. • Energy levels are infinitely degenerated with regard to the l -waves. [ABSTRACT FROM AUTHOR]

The Gaussian confinement potential (AGCP) and triangular confinement potential (TCP) was considered in quantum well (QW) growth and perpendicular directions. The cyclotron frequency, temperature, and hydrogen-like impurity characteristics of ground state binding energy (GSBE), ground state energy (GSE), LO phonons mean number and vibrational frequency (VF)of impurity magnetopolaron in special QWs were investigated. Analytical equations were obtained for GSBE, GSE, LO phonons mean number and VF as functions of cyclotron frequency, Coulombic impurity potential, temperature, AGCP range and barrier height, polar coordinate system confinement strength and polar angle. We found that GSBE, GSE, LO phonons mean number and VF absolute values were increased by the increase of temperature and barrier height of AGCP, while they were enhanced with AGCP decaying range. Physical quantities were improved by increasing the strength and polar angle of polar coordinate system confinement. These results proved the potential application value of optoelectronic properties in low-dimensional devices. [ABSTRACT FROM AUTHOR]

Simulating the signal transmission process in neurons is crucial in computational neuroscience. However, much of the existing researches simplifies signal transmission in a single neuron to a basic mathematical process. In this article, we introduce an all-optical silicon artificial neuron incorporating an aperiodic gold monotile structure. This structure enables the simulation of uniform signal transmission within the axon. Furthermore, we propose a III-V quantum wells protocol to achieve the amplification function of nodes of Ranvier in neurons. • A possible simulation method for the transmission process of neural signals based on silicon waveguides is proposed. • This method could imitate the uniform signal transmission and the signal amplification. • This method provides a potential hardware strategy for neuroscience, which is high adaptable to other optical modulations. [ABSTRACT FROM AUTHOR]

• Two-dimensional perovskite (C 8 H 17 NH 3) 2 PbBr 4 crystallizes into Acam structure. • (C 8 H 17 NH 3) 2 PbBr 4 has a phase transition at 190 K. • The narrow and broad bands originate from free and self-trapped exciton emission. • The self-trapping depth of self-trapped exciton state is 26.3 meV. The structural versatility of organic compounds imparts manifold properties to hybrid organic−inorganic perovskites, where two-dimensional (2D) halide perovskites are potential future platforms for light-emitting devices because of their unique quantum well configuration and dielectric confinement. Notwithstanding the numerous studies on the organic−inorganic perovskites carried out to date, precisely charactering the structure and photoluminescence mechanism remain considerable challenges. Herein, by applying Rietveld refinement, we have obtained crystal structure and atomic sites of 2D layered OA 2 PbBr 4 perovskite, which undergoes a phase transition at 190 K with activation energies of 29.6 and 3.8 meV for the two phases, respectively. The theoretical analysis based on the crystal structure were performed to understand the nature of vibrations and band structure. Steady-state PL shows a narrow emission and a broad emission located at 409 and 487 nm, respectively. With temperature cooling down to 118 K, narrow emission gradually narrowed and enhanced. Meanwhile, intensity of broad emission first weakens and then increases. The turning point occurs near 198 K. By applying time-resolved PL (TRPL) and transient absorption (TA) spectra experiment, we observed a rapid carrier transfer from the FE to the STE state, and demonstrated the narrow and broad bands originate from free exciton and self-trapped exciton emission, respectively. And the self-trapping depth is proved to be 26.3 meV by low-temperature PL. Our findings indicate the synthesized 2D perovskite has potential applications in optoelectronic and display devices. [ABSTRACT FROM AUTHOR]

In order to effectively regulate the luminescence performance of MQW and enhance its optical quality, it is crucial to investigate the InGaN/GaN MQW's structure and luminescence properties. In this study the focus is how they are affected by low-temperature cap (LT-cap) layer's thickness which is grown above each InGaN well layer during growth process of InGaN/GaN multiple quantum well (MQW) samples in MOCVD system. This was achieved by analyzing high resolution X-ray diffraction (HRXRD) spectra, electroluminescence (EL) spectra, temperature-dependent photoluminescence (TDPL) spectra, and micro-area fluorescence imaging of these samples. The results show that changes in LT-cap layer's thickness even have no significant impact on some structural parameters of MQW, such as the thickness of the well layer, but have an influence on the In component of the well layer. Due to the existence of LT-cap layer, dissociation of InGaN can be effectually reduced. In addition, the augmentation of LT-cap layer's thickness will make polarization effect of the QW sample more remarkable, so that the blue shift of the EL peak with the augmentation of current injection increases. The change of LT-cap layer's thickness will also influence distribution of the tail states of the quantum wells, which leads to a different localization states for injected carriers. As LT-cap layer becomes getting thicker, the material's internal quantum efficiency (IQE) tends to decrease, which may result from an increase in non-radiative recombination centers. • The thickness of LT-cap layer have no significant impact on some structural parameters of MQW, but have a certain degree of influence on the In component of the well layer. • Different LT-cap layers will Influence the distribution of band-tailed states, resulting in different energies of carriers emigrated from the localized states. • The polarization effect of the sample more remarkable when increasing of the thickness of LT-cap layer. [ABSTRACT FROM AUTHOR]

Wireless energy harvesting is an important application of microwave wireless energy transmission system, but due to the weak energy of RF signals in the 2.45 GHz band, its rectification efficiency is not ideal. As one of the core rectifier components of wireless weak energy harvesting system, the performance of MOSFET determines the rectification efficiency of the system, and its optimized design to improve the rectification efficiency is an important direction of current research in the field. In view of this, this paper proposes and designs Ge quantum well channel PMOS for wireless weak energy harvesting at 2.45 GHz, aiming to improve the rectification efficiency of wireless weak energy harvesting systems. Starting from adjusting the structural physical parameters of the MOS tubes, the absolute value of the threshold voltage is reduced in the weak energy density region, which in turn improves the rectification efficiency of the device. Then, the novel diode connection with the introduction of substrate bias effect is compared with the conventional connection using an ADS simulation circuit, and the simulation results show that the leakage current is smaller and the rectification efficiency is higher under the novel connection. On this basis, a Ge quantum well channel PMOS device is proposed. Compared with the Ge surface channel, the hole mobility of the quantum well channel will be greatly improved, and its rectification efficiency can also be improved. The device is connected to the rectifier circuit with a novel connection and simulated using Silvaco's Mixedmode module. The results show that the rectification efficiencies of the Ge quantum well channel MOS reach 13.53 % and 32 % at low input powers of −20.34 dBm and −6.28 dBm, respectively, which are 3.3 and 1.14 times higher than those of the conventional surface channel MOS. • Wireless energy harvesting system that collects RF signals and converts them into DC currents. • MOSFETs are core rectifier components for wireless weak energy harvesting systems. • Threshold voltage of MOSFET affects rectification efficiency in weak energy region. • MOS transistor rectification efficiency enhancement with novel connections. • Ge quantum well channel enhances device hole mobility. [ABSTRACT FROM AUTHOR]

• C-doped InAl(Ga)As layer was introduced between a Zn-doped InP layer and MQWs layers. • Zn concentrations in the MQWs with and without C-doped payer were evaluated by SIMS. • Influence of Zn diffusion on extinction characteristics of the EAMs was evaluated. We propose a novel epitaxial layer structure to prevent Zn from diffusing into a multiple quantum well (MQW) layer of an electro-absorption modulator (EAM). Zn is practically employed as a p-type dopant in an InP material system, but there is a technical issue of unintentional Zn diffusion. In this work, we introduce a novel C-doped p-type layer between a Zn-doped p-cladding layer of InP and MQW to both reduce Zn diffusion and accurately define a p-i-n junction interface. The Zn concentrations in the MQW for each device are compared by measuring secondary ion mass spectrometry (SIMS). To clarify how the reduction of diffused Zn affects the EAM characteristics, we fabricate the EAMs with each epitaxial structure and compare their extinction ratio characteristics. The evaluation of extinction ratio per EAM capacitance successfully demonstrates that employing the C-doped layer effectively improves the EAM characteristics. [ABSTRACT FROM AUTHOR]

150 mm Indium Phosphide wafers are now commercially available with crystal quality comparable to wafer of smaller radius. This may pave the way for scaling up the production of a multitude of photonic devices for Datacoms operating in the 1.30- 1. 55 μ m infrared range with a gain in wafer surface of factor 4 and a reduction of roughly 50% in die cost. To achieve this goal, it is of utmost importance to prove that both AlGaInAs and InGaAsP quaternary compound semiconductors can be grown by metal–organic chemical vapor deposition (MOCVD) on wafers of larger sizes with both thickness and composition uniformities comparable to those achievable on 75 mm. In this article, we report pioneering production technology developments based on the Planetary Reactor® design. Both reactor and related inlet geometry have been deeply revisited with the introduction of a novel 4-fold injector, which in combination with Cl 2 In-situ chamber clean, prove to enable such transition in wafer size. Sub-nanometric photoluminescence in-wafer uniformities are demonstrated and historic challenges, such as drift in material composition of highly sensitive InGaAsP alloys during a production campaign, are addressed thanks to this unique combination. Uniformity, tunability and reproducibility results are thus presented for two prototypical case scenarios: a highly strained AlGaInAs multiple quantum well (MQW) and a bulk InGaAsP layer with wavelength emission of 1550 nm and 1100 nm respectively to corroborate reactor flexibility in meeting industry requirements for next device generation. [Display omitted] • MOCVD growth of IIIAsP compound semiconductors on 150 mm Indium Phosphide wafer. • IIIAsP material uniformity tuning by 4-fold gas inlet system. • Cl 2 based in-situ chamber clean for superior system repeatability. [ABSTRACT FROM AUTHOR]

The paper theoretically explores the variations in nonlinear optical rectification (NOR), second (SHG), and third harmonic generation (THG) coefficients of an n-type quadruple δ-doped GaAs quantum well in the presence of electric, magnetic, and THz laser fields. The energies of subbands and associated wave functions are derived through the solution of the Schrödinger equation, utilizing effective mass and parabolic band approximations. The findings indicate that the applied external electric and magnetic fields significantly influence both the magnitudes and the positions of the peaks in NOR, SHG, and THG concerning the incident photon energies. In addition to the influences of electric and magnetic fields, subjecting the system to an intense laser field results in noticeable changes in the THG, SHG, and NOR coefficients. These numerical findings regarding the optical properties of quadruple δ-doped quantum wells in the presence of external fields could offer valuable guidance for experimental studies. [ABSTRACT FROM AUTHOR]

We explore the impact of external fields on the absorption coefficients and relative refractive index changes in a quantum cascade laser profile-like heterostructure that consists of a triple asymmetric quantum well. Firstly, we solve numerically the time-independent Schrödinger equation by using the diagonalization method under the effective mass and parabolic band approaches, to obtain the energy levels and wavefunctions. Then, we evaluate the optical coefficients from the analytical expressions derived from the compact density matrix method. The obtained results put forth that the resonant peaks of optical coefficients shift to higher (lower) energies by increasing the value of the electric (magnetic) field. These results indicate that it would be possible to adjust the optical properties of these structures to the desired range with external fields. As a result, we hope that new optoelectronic devices based on asymmetric triple quantum wells can be developed using the features found here. [ABSTRACT FROM AUTHOR]

This article reports the analysis of type-II DQW (double quantum well) heterostructure having the specified layers of GaAs 0.15 Sb 0.85 , In 0.55 Ga 0.45 As and In 0.1 Ga 0.9 As ternary compounds for the design of QW infrared photo-detector. For the optimized heterostructure, the optical characteristics (i.e. absorption spectra) are studied with the help of k.p theory. Using k.p approach the electronic and holes wavefunctions followed by E-K curves of conduction and valence bands are calculated and analyzed. In addition, the dipole and momentum matrix elements are also calculated to understand the transition mechanism which is responsible for optical absorption. For the designed In 0.1 Ga 0.9 As/GaAs 0.15 Sb 0.85 /In 0.55 Ga 0.45 As DQW heterostructure, the partial as well as overall optical absorption are calculated in the X-and Y- polarization modes. Under X- polarization mode, the peak optical absorption corresponds to two wavelengths ∼ 2700 and 3600 nm. At 2700 nm, the absorption peak is much higher and sharper than that at ∼3600 nm. In the Y- polarization mode the peak absorption is available at ∼ 2550 and 3350 nm. On behalf of the simulating results, it can be claimed that the proposed DQW heterostructure may be suitable in designing the QW photo-detectors for detecting the radiation in SWIR (short wave infrared) region, and hence useful in various kind of applications such as in industries, telecommunications, remote sensing, non-invasive diagnoses, medical imaging, spectroscopy, and environmental monitoring. [ABSTRACT FROM AUTHOR]

A Bose–Einstein condensate (BEC) formed on a curved surface with a distinct topology has been a hot topic of intense research, in search of new phenomena in quantum physics as well as for its possible application in quantum computing. In addition to the study of a spherical-shell-shaped BEC, we studied the formation of a cylindrical-shell-shaped harmonically-trapped dipolar BEC of 164Dy atoms theoretically using an improved mean-field model including a Lee-Huang-Yang-type interaction, meant to stop a collapse at high atom density. To test the robustness of the cylindrical-shell-shaped BEC, here we study its expansion in the same model. We find that as the harmonic trap in the x and y directions are removed, maintaining the axial trap, the cylindrical-shell-shaped BEC expands in the x - y plane without deformation, maintaining its shell-shaped structure. After an adequate radial expansion, the axial trap can be relaxed for a desired axial expansion of the cylindrical-shell-shaped BEC allowing its observation. • Expansion dynamics of cylindrical-shell-shaped strongly dipolar condensates. • Both circular and elliptical shell shapes studied. • Expansion dynamics is found to be independent of allowed variation of parameters. [ABSTRACT FROM AUTHOR]

The refinement of interface structure in InGaAs/AlGaAs multiple quantum wells (MQWs) through molecular beam epitaxy (MBE) is crucial for enhancing their luminescence performance. The influencing mechanisms of the GaAs insertion layer (ISL) thicknesses on the interface structure and luminescence properties of InGaAs/AlGaAs MQWs were investigated by varying the GaAs ISL thickness variations and optimizing growth parameters. In our designed InGaAs/AlGaAs MQWs structures, GaAs ISL with thickness variables of 0 nm, 0.5 nm, 1 nm, 2 nm, and 4 nm were inserted between the interfaces of the InGaAs well layer and the AlGaAs barrier layer. Through experimental characterizations. The introduction of the GaAs ISL resulted in a gradual transition of the MQWs surface morphology from a three-dimensional (3D) island structure to a typical step-flow surface morphology, leading to the reduction in surface roughness and enhancement of hetero-interfaces quality. Moreover, the GaAs ISL with thickness exceeding 2 nm effectively inhibited the segregation of indium atoms, promoting the ordering of interface alloys and decreasing the polarization degrees from 3.76 % to 2.09 %. Temperature-dependent PL measurements indicated that the GaAs ISL could reduce interface defects and the density of non-radiative recombination centers, thereby enhancing the radiative recombination efficiency of MQWs and ultimately increasing the peak intensity of photoluminescence by 3.4 times. This work is significance for understanding the luminescent properties of InGaAs/AlGaAs MQWs, which provides reference highly efficient optoelectronic devices development. • Optimized MBE growth improves InGaAs/AlGaAs MQWs quality. • GaAs insertion layer suppresses intermixing, enhances interface quality. • Optimized GaAs insertion layer thickness increased MQWs PL intensity 3.4x. [ABSTRACT FROM AUTHOR]

Far ultraviolet C (UVC) light sources work well for a variety of applications, such as water purification, bacteria and virus sterilization, and sensing, because of their short wavelength. Herein, the recognized problems with a conventional UVC-LED are solved by creating a triode structure UVC light source tube (UVC-LST) operating at ∼268 nm employing a carbon nanotube (CNT) electron emitter as an excitation source. The UVC light emission of an aluminum reflector-capped AlGaN multiple quantum well (MQW) heterostructures synthesized on a nanopatterned sapphire substrate based on a cathodoluminescence (CL) layer is assessed. For luminescence results comparison, the heterostructure of AlGaN-based MQWs was fabricated with various QW layer thicknesses of 1, 1.5, and 2 nm. The utilization of a thinner QW layer with a thickness of 1 nm significantly improved the UVC light emission efficiency compared to the UVC-LSTs fabricated with thicker QW layers of 1.5 nm and 2 nm. The UVC-LST with the 1 nm QW layer exhibited approximately a 30 % improvement in light output power compared to the UVC-LST with a 1.5 nm QW layer, and closely a 33 % improvement compared to the UVC-LST with a 2 nm QW layer. Moreover, the UVC-LST with the thinner QW layer demonstrated a high power efficiency of 5.24 % when operating on a 2-inch light-emitting area, while consuming a low power of 7 W. This high power efficiency indicates that a significant portion of the input electrical power is effectively converted into UVC light output, highlighting the superior performance of the UVC-LST based on the 1 nm QW layer design. • Far ultraviolet C (UVC) light sources based triode structure was successfully fabricated. • A carbon nanotube (CNT) electron emitter served as an excitation source. • AlGaN-based MQWs was fabricated with various QW layer thicknesses. • The thinner QW layer with a thickness improved the UVC light emission efficiency. • The thinner QW layer demonstrated a high power efficiency of 5.24 %. [ABSTRACT FROM AUTHOR]

Using a comprehensive approach that includes structural, optical, and theoretical studies, this work offers research demonstrating the capability to evaluate the individual and total effect of strain and segregation on the spectral characteristics of quantum well structures. The samples under investigation contain double asymmetric tunnel-coupled quantum wells based on solid solutions of indium, gallium and aluminum arsenides. The photoluminescence spectra of the structures were observed experimentally at two measurement temperatures, namely 77 K and 300 K. Since the photoluminescence peaks are very sensitive to the quantum well profile, the photoluminescence emitting regions of the grown structures can differ in energy by up to 50 meV due to the design diversity. In turn the elastic strain and compositional segregation effects can lead to the energy shift of the photoluminescence peaks about such order, hence it is important to choose a technique to identify these contributions. Control measurements of the indium content and elastic strains were carried out by means of transmission electron microscopy, namely, by the coordinated application of characteristic electron energy loss spectroscopy and the geometric phase method. Theoretically, using the obtained structural data, the strained quantum well potential profile, quantum-size levels, the envelope wave functions and interband transition matrix elements were calculated. The strong agreement between the modelled and experimental spectra validates our theoretical simulation. • Analysis of the strain and the segregation impact on the optical spectra for the heterostructures has been performed. • The suggested approach reduced the deviation between experimental and simulated PL spectra to 10%. • Structural and theoretical complex approach offer to evaluate both total and individual effect of the strain and the segregation on the PL characteristics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three new optical responsive molecules AT-TPIo , AT-DPIo , and AT-HDPIo have been successfully synthesized. • All of these compounds exhibited remarkable invisible photochromism accompanied by pronounced "turn-off" fluorescence. • AT-TPIo demonstrated high selectivity and sensitivity as a sensor for the detection of I− ions. Three novel diarylethene fluorescent molecules based on a thiophene-imidazole core have been successfully synthesized. Their photophysical properties, including photocyclization and ions response characteristics, as well as quantum chemical calculations were systematically investigated. All compounds exhibited significant invisible photochromism upon photocyclization, resulting in remarkable fluorescence "turn-off" properties. This phenomenon can be attributed to photoisomerization, specifically the transition from the open-ring isomer to the closed-ring isomer during this process, which was confirmed by 1H NMR data analysis. Moreover, AT-DPIo demonstrated high selectivity toward I− with pronounced changes in absorption from colorless to yellow and fluorescence from bright yellow to dark, enabling a limit of detection for I− at 9.75 × 10−7 mol L−1. These exceptional sensing properties make it suitable for rapid "naked-eye" detection of I− using test strips. [ABSTRACT FROM AUTHOR]

In this paper, we first characterize a superlattice structure created by repeating a heterostructure formed from two armchair graphene nanoribbon (AGNR) segments with different widths. We investigate the electronic and transport properties of this structure by varying its widths and lengths to demonstrate the tunability of its overall band gap. The plot of the local density of states shows the formation of localized states at the low band gap segments of the superlattice. The superlattice is then used as a barrier to create a double barrier quantum well (DBQW) to design a proposed resonant tunneling diode (RTD) structure. We observe this device's negative differential resistance (NDR) operation for a range of bias voltages between the contacts. We study the effect of dimensional parameters on the RTD performance. The non-equilibrium Green's function method, based on a tight-binding model, is employed for numerical computation. • Tight binding approach considering overlapping matrix and hopping parameter up to 3rd nearest neighbor. • Band gap modulation of U-cut edge patterned AGNR. • Transport properties of DBQWs for graphene nanoribbon using Non equilibrium green's function. • LDOS at the quasi bound state due to quantum well. • Performance of graphene based Resonant Tunneling Diode. [ABSTRACT FROM AUTHOR]

The "Green Gap" remains a significant challenge to date, mainly due to the substantial compressive stress that occurred when necessitating high-indium compositional multiple quantum wells (MQWs) grown on GaN template. To address this issue, we introduce and analyse two distinct practical and commercially viable strain relief layer (SRL) prior to the growth of MQWs, namely type-I and type-II, each incorporating varying indium compositions. Type-I utilizes In Y Ga 1−Y N/GaN superlattices, while type-II employs thin layers of In Z Ga 1−Z N. The People and Bean's model is applied to calculate the critical thickness required for achieving fully strained SRL experimentally. Through theoretical and numerical analyses, we optimize the green-LED, achieving remarkable results including an 84.7% internal quantum efficiency, minimal 25% efficiency droop at 200 A/cm2, and a 27 nm red-shifted electroluminescence spectrum with a narrow full-width half-maxima of 21.4 nm. This study not only advances our understanding of strain engineering in green-LEDs but also provides valuable insights for optimizing higher indium-content optoelectronic devices to achieve longer wavelengths, including yellow and red-LEDs, in the future. [Display omitted] • Reduced efficiency in green-LEDs primarily due to high indium MQWs growth on GaN. • Two distinct strain relief layer (SRL) is introduced for superior lattice alignment. • Explored In Y Ga 1−Y N/GaN superlattice and a thin layer of In Z Ga 1−Z N as SRL. • People and Bean's model is used for critical thickness calculation. • Achieved 84.7% internal quantum efficiency with 24% efficiency droop at 200 A/cm2. The reduction in quantum efficiency observed in green-LEDs, often referred to as the "Green Gap", is primarily influenced by the fact that high indium compositional In x Ga 1−x N/GaN (x = 25 %) green-multiple quantum wells (green-MQWs) are typically grown on a GaN. This arrangement leads to substantial compressive stress within the green-MQWs. To address this challenge, our approach involves achieving superior lattice constant alignment within the green-MQWs by growing a fully strained strain relief layer (SRL) before the growth of the green-MQWs. Our comprehensive theoretical study, coupled with numerical simulations, aimed to investigate the impact of two types of SRL techniques: type-I, which involves superlattice of In Y Ga 1−Y N/GaN, and type-II, which incorporates a thin layer of In Z Ga 1−Z N. In conclusion, we proposed a novel LED structure that exhibits the internal quantum efficiency of 84.7 %, minimal efficiency droop of 24 % at 200 A/cm2 and 27 nm red-shifted electroluminescence characteristics having narrower FWHM of 21.4 nm. [ABSTRACT FROM AUTHOR]

The exploration of two-dimensional (2D) materials in highly performance optoelectronic device is critical for the practical applications. Traditionally, GaN related semiconductors uses complicated multiple quantum wells to increase the overlap of electron and hole waves for highly efficient light emitting diode (LED). In this work, through designing the Graphene/MoS 2 heterostructure for increasing the hot electron lifetime and subsequently enhancing the process of carrier multiplication (CM), we successfully realize the highly efficient Graphene/MoS 2 /p-GaN LED with external quantum efficiencies (EQE) of 15.89% under 0.625 mA/mm2. Compared with the Graphene/p-GaN LED device, the addition of MoS 2 leads to stronger light output and the maximum EQE increased by 61%. The energy bands alignment between MoS 2 and GaN squeezes the hole at the MoS 2 layer, when the numbers of holes are increased by graphene as a result of CM effect, which recombines with electron at the surface of GaN defects resulting in the strong light output at reversed bias. We believe that this work will bring a brand new insight of realizing high efficient 2D materials based LED and optoelectronic devices. [Display omitted] • We successfully realize hot carriers assisted mixed-dimensional Graphene/MoS 2 /p-GaN LED. • The CM effect in the Graphene effectively increases the accumulation of carriers at the junction area between the MoS 2 and p-GaN. • The radiative recombination on the surface of p-GaN improve the EQE. [ABSTRACT FROM AUTHOR]

In the n-InGaAs/GaAs double quantum well, the suppression of resonant resistance by an in-plane magnetic field B ≤ 9 T in the temperature range T = (1.8–70) K is studied. The electron quantum lifetime, τ q , is determined and the contributions of various scattering mechanisms to τ q (T) are separated. It is shown that the observed nonmonotonic temperature dependence of the electron quantum lifetime is due to a combination of the interference contribution from the exchange electron-electron interaction in the ballistic regime and the inelastic electron-electron scattering in the diffusion regime (Fukuyama-Abrahams mechanism). • Resistivity of InGaAs/GaAs strongly coupled double quantum wells in in-plane magnetic field are analyzed. • Atypical for 2D systems with weak disorder nonparabolic temperature dependence of electron quantum lifetime 1/ τ q (T) is found. • It is shown that 1/ τ q (T) is determined by interference contribution to conductivity and inelastic electron-electron scattering. • Linear increase of τ q (T) at T ˃ 20 K is due to interference induced electron-electron exchange interaction. • Inelastic electron-electron scattering rate is described with good accuracy by Fukuyama-Abrahams law in the diffusion limit. [ABSTRACT FROM AUTHOR]

The effect of thermal annealing on the optical properties of In 0.36 Ga 0.64 As 1-y N y /GaAs double quantum wells (QWs) grown on different GaAs planes was investigated for two sets of samples having y = 0 % and 1 % nitrogen. It was found that annealing at 700 °C for 30 seconds is the optimum annealing temperature which improves the photoluminesces (PL) efficiency for all QWs. The PL enhancement is larger in samples with 1 % nitrogen than 0 %. This PL improvement, which may be explained by the annihilation of defects introduced by the incorporation of nitrogen, is accompanied by a blue shift. Secondary ion mass spectroscopy (SIMS) shows that In/Ga intermixing, which occurs at the interface between QW and barrier, could account for the origin of this energy shift in QWs grown on (311)A and (100) planes. The amount of diffusion of In out of the QW depends on the growth plane. It is larger for QWs grown on (311)B plane as compared to the other planes. However, in contrast to the (311)B QWs the nitrogen content in the (100) and (311)A QWs doesn't change upon annealing. • Optimal Annealing Conditions: The study identifies 700 °C for 30 seconds as the optimal annealing temperature, unveiling a significant enhancement in photoluminescence efficiency. • Nitrogen's Impact: Nitrogenated samples show higher PL enhancemnet than control. • Nuanced Interplay: PL peak blueshift depends on growth plane and N content due to Ga/In intermixing. In diffusion is higher in (311)B planes than in other planes. [ABSTRACT FROM AUTHOR]

We theoretically investigate the nonlinear effects of a magnetic field on the relaxation process of exciton–polaritons toward Bose–Einstein condensation in GaAs quantum wells. Our study reveals that the modification of the exciton's effective mass, Rabi splitting, and dispersion significantly alters the relaxation rate of polaritons as they approach condensation. By employing a quasi-stationary pump, we clarify the dynamics of the total and condensed polariton populations in response to varying magnetic field strengths. Notably, we demonstrate that under low-energy pumping conditions, the presence of a magnetic field significantly suppresses condensation. This suppression is attributed to the decreased scattering rate between energy levels, which is a consequence of the reduced steepness in the high-energy dispersion. Conversely, increasing both the pump energy and the magnetic field can enhance relaxation efficiency, leading to a substantially larger number of condensed polaritons. • The relaxation kinetics of quantum well polaritons under a magnetic field were studied. • Low-energy pumping reduces condensation in a magnetic field by lowering scattering rates. • High magnetic fields and high-k pumping enhance condensation via steeper dispersion. [ABSTRACT FROM AUTHOR]

In this study, the first excited state binding energy and the linear, non-linear and total optical absorption coefficients (OAC) of a hydrogenic impurity in a surface quantum well (SQW) of the type vacuum/GaAs/Al x Ga 1-x As are calculated as functions of the incident photon energy, the Al content and the well width using a variational method within the effective mass approximation. The results show that the first excited state energy and the linear, non-linear and total OAC are strongly influenced by variations in the well width, and only a slight, yet interesting, impact of the Al content is observed. A redshift in the extreme values of the linear, non-linear and total OAC is found for a SQW with fixed Al content and variable width, whereas no significant variation is observed in the reciprocal system of fixed width and variable Al content. [ABSTRACT FROM AUTHOR]

The effect of electronic and high-κ dielectric quantum screening (ES and DS) on the impurity-limited electron transport properties of quantum well/high-κ dielectric barrier type heterostructures with two-dimensional electron gas (2DEG) is studied theoretically. Characteristic of these heterosystems the 2D compound forms of screened impurity potential are employed for the first time. In the framework of 2D Debye-Hückel potential form an electron momentum relaxation time (τ) expression depending on the impurity 2D screening radius is obtained analytically. A numerical analysis of τ is carried out for the realistic HfO/InSb/HfO 2 QW heterostructure taking account both the finite mismatch of the energy bands at the heterointerface and the energy band non-parabolicity of InSb. The contributions of screened potential compound 2D forms to τ are established depending on QW width. A significant suppression of the scattering rate τ − 1 (by an order of magnitude) is received with accounting of ES + DS combined effect. [ABSTRACT FROM AUTHOR]

This research investigates the spin-dependent transmission attributes and associated Giant Magnetoresistance (GMR) effect emerging from spin-polarized electron tunneling in a GaAs quantum well superlattice (QWS). The influence of Rashba and Dresselhaus spin-orbit interactions (SOIs) on transport properties is analyzed under the framework of the scattering matrix method. Our quantitative findings revealed that these spin-orbit couplings (SOCs) introduce inherent spin-filtering mechanisms, significantly influencing transmission probabilities. Furthermore, numerical estimations proved that external perturbations including pressure, temperature and structural modifications considerably impact the quantum transport characteristics of the scrutinized system. Additionally, major outcomes suggest that precise manipulation of spin-dependent transport in GaAs QWS holds promise for advancing spintronics technology. It is found that with well-tuned parameter values, the SOCs behave as a spin-dependent barrier modifying the band shape and its anisotropy. This study offers novel insights into the fundamental physics governing spin-dependent transport within quantum superlattices with promising implications for the development of advanced spintronic devices. [ABSTRACT FROM AUTHOR]

In this study, polaron effect in 2D metal halide perovskite materials (TMHPMs), which naturally form quantum well (QW) structures, has been investigated. Polarization of carriers and lattice within these structures was explored based on unitary transformation and variational methods. Specifically, lattice polarization and energy level transition spectra of strong coupling polaron in parabolic potential metal halide perovskite QWs (MAPbCl 3 , MAPbBr 3 , and MAPbI 3) were studied. Also, we calculated ground and first excited state energies, excitation energy, transition frequency, and vibration frequency of a TMHPM QWs. Our results indicated that parabolic potential confinement intensity affected related physical quantities, which provided insight to investigate metal halide perovskite materials and polaron effect. [ABSTRACT FROM AUTHOR]

Imidazolium-based ionic liquids (Imim-ILs) have great application potential in catalyzing the electrochemical CO 2 reduction reaction (CO 2 RR). However, the microscopic mechanism by which imidazolium-based cations promote CO 2 RR remains unclear. In this study, we observe that despite the structural differences between [Bmmim]+ and [Bmim]+, both exhibit high catalytic activity during the electrochemical CO 2 RR. Electrochemical and in situ spectroscopic analyses, as well as Quantum Theory of Atomic in Molecules (QTAIM), reveal that the pivotal step in the CO 2 RR mechanism facilitated by [Bmmim]+ and [Bmim]+ involves the formation of [Bmmim]···CO 2 or [Bmim]···CO 2 complexes via hydrogen bond. These complexes enhance the electrochemical reduction of CO 2 or ·CO 2 - on electrode, facilitating efficient CO production. Specifically, the [Bmmim]···CO 2 complex forms at the C4-H position of the imidazole ring, while in the [Bmim]···CO 2 complex, it forms at the C2-H position. [Display omitted] • Formation of [Imim]···CO 2 is the key step for promoting the CO 2 electroreduction. • [Imim]···CO 2 is formed through hydrogen bonds between Imim-ILs and ·CO 2 -. • The hydrogen bonds are formed at C4-H for [Bmmim]···CO 2 and C2-H for [Bmim]···CO 2. [ABSTRACT FROM AUTHOR]

Due to their low toxicity and high-temperature stability, lead-free quasi-2D metal halide perovskites (MHPs) are promising materials for optoelectronic applications. However, understanding their structural and optoelectronic properties, especially excitonic effects (electron-hole pair, e - h), is challenging due to their quantum well topology. We propose an efficient protocol for band gap correction of Cs 2 ZnX (X = Cl 4 , Br 2 Cl 2 , and I 2 Cl 2) and Cs 2 PbI 2 Cl 2 (used as a benchmark) quasi-2D MHPs. This protocol is based on a relativistic quasiparticle approach (DFT-1/2) using density functional theory (DFT). We first examined the hybrid contributions of the halide alloys, leading to excitonic characterization using the Bethe–Salpeter equation within the maximally localized Wannier functions tight-binding method. This method provides a cost-effective approach for describing e - h quasiparticle effects. Additionally, we analyzed the crystal structure, thermodynamic stability, and optoelectronic properties of the newly synthesized Zn-based systems, focusing on their structural stability mechanisms. We found a correlation between the allocation of Cs+ cations in the crystal structure and the formation of two distinct stabilization patterns, influenced by the radii of the metal (Zn or Pb) and halide components. The relativistic correction of the band gap energies yielded results within 10 % of the experimental values. Furthermore, incorporating e - h quasiparticle effects for Cs 2 PbI 2 Cl 2 resulted in an exciton binding energy of 0.160 eV, in excellent agreement with experimental data. This work represents a significant advance in the optoelectronic characterization of Cs 2 ZnX systems, previously unexplored for their excitonic properties. [Display omitted] • The stability of halide alloys depends on the allocation of the cavity cation and the crystal cavity space. • Quasiparticle correction (DFT-1/2) with weight correlates well with experimental data. • Exciton effects via TB–BSE method describes optical properties in Cs 2 MY 2 X 2 systems (M = Pb, Zn; Y and X = Cl, Br, I). • The PCE of the systems was determined using Shockley–Queisser and SLME models, offering a thorough optoelectronic analysis. [ABSTRACT FROM AUTHOR]

The electrical and luminescent characteristics of the heterostructure with a 20 nm-wide n -InAsSbP/ n -InAs 0.95 Sb 0.05 / p -InAsSbP single quantum well, grown on an n -InAs substrate by the MOVPE method, have been studied. An intense room temperature electroluminescence (EL) with a maximum near the photon energy of 0.34 eV and a FWHM of 32 meV was discovered. It was established that the EL in such single quantum well has been emitted due to type I radiative transitions between the ground levels of electrons and holes both at forward and reverse bias. The characteristics of heterostructures with a single quantum well and the active region based on a bulk InAsSb layer of the same composition have been compared. • Room temperature electroluminescence was found in InAsSb/InAsSbP quantum well. • Electroluminescence was emitted at both polarities of applied external bias. • Spectral position of emission band was constant for the forward and reverse bias. • Phase of electroluminescence remained unchanged when bias polarity was switched. [ABSTRACT FROM AUTHOR]

A comparative study of the optical absorption properties of the nanostructured transparent conducting oxides (TCOs) such as zinc oxide (ZnO), cadmium oxide (CdO), and gallium oxide (Ga 2 O 3) in the presence of a magnetic field B has been performed. The cyclotron resonance absorption power in the TCO materials of the symmetric Pöschl–Teller quantum well (SPTQW) and the full width at half maximum (FWHM) are obtained by applying the operator projection method, the confined phonon model of Huang–Zhu, and the profile technique. Our main results are as follows: The order of the absorption power intensity in these TCOs from strongest to weakest is Ga 2 O 3 , ZnO, and CdO, whereas that of the FWHM from largest to smallest is CdO, ZnO, and Ga 2 O 3. This is because the optical phonon frequency in CdO is the smallest, while that in Ga 2 O 3 is the largest. The influences of the magnetic field strength, the thickness, and the temperature on the FWHM in ZnO, CdO, and Ga 2 O 3 become more significant as the phonon is confined. The optical absorption properties of the TCOs are remarkably enhanced due to the confinement of phonon, and those of CdO are the most dominant among the Ga 2 O 3 , ZnO, and CdO. The results of our study can provide particular insights for the design of optoelectronic devices. • Optical properties of transparent conducting oxides based on nanostructures are studied. • Absorption power and FWHM in ZnO, CdO, and Ga 2 O 3 are calculated and compared. • Temperature, magnetic field, and thickness-dependent FWHMs of ZnO, CdO, and Ga 2 O 3 are studied. • FWHM from largest to smallest is CdO, ZnO, and Ga 2 O 3. • Optical properties of TCOs are enhanced significantly due to phonon confinement. [ABSTRACT FROM AUTHOR]

• A very compact vector force sensor achieved through on-chip monolithic integration strategy. • Introduction of microstructures on the surface of PDMS elastomers enhances the sensor's performance in terms of sensitivity and hysteresis. • Simultaneous fabrication of micro-LEDs and PD on sapphire-based AlGaInP MQW chips. • Compatible with wafer-level microfabrication technology, enabling high-cost effectiveness. Optical principle-based force sensors offer significant advantages in detection applications for surgical robots and wearable devices. With the rapid development in these fields, there is an increasingly urgent demand for improving sensor performance and reducing sensor size. Here, we present a monolithic micro-vector force sensor by integrating the sapphire based AlGaInP micro light-emitting diodes (micro-LEDs) and a surface micro-structured polydimethylsiloxane (PDMS) elastomer. The sensor primarily operates based on the overlapping between the emission spectra and the detection spectra of the multiple quantum well (MQW) structure in the micro-LEDs and the modulation of the reflectance of the sapphire interface by highly elastic microstructures. This monolithic micro-vector force sensor is characterized by its small footprint with a diameter of only ∼7 mm, and it exhibits good real-time response performance with response sensitivities to normal force and shear force of 0.38 nA/mN (0–2 N) and 1.3 nA/mN (0–200 mN). Furthermore, this monolithic integrated device can be manufactured on a large scale and at low cost using wafer-level microfabrication processes. Additionally, the sensor operates in the biologically safe red light spectrum, thus offering broad prospects for applications in fields such as biomedicine and wearable devices. [ABSTRACT FROM AUTHOR]

• Enhanced efficiency of AlGaN-based Deep-UV-LD through composition grading of quantum barriers and EBL. • Utilized PICS3D software for simulation and analysis of optical properties. • Achieved a significant increase in output power (up to 60 mW) and conduction band barrier height (570 meV). • Improved device intensity, gain, and stimulated recombination rate. • Reduced valence band barrier height, threshold voltage, threshold current, and electron current density. • Demonstrated that increase composition grading in AlGaN-based DUV-LD enhances device performance. • Proposed asymmetric composition-graded QB and EBL structures to boost DUV-laser efficiency. • Conducted an in-depth numerical study showing • reduced threshold current, voltage, and carrier leakage. • Highlighted the potential of the proposed laser structure for improving Deep-UV-laser performance. A deep ultraviolet (DUV) laser diode is a compact and efficient semiconductor device that emits laser light in the deep ultraviolet range. Its unique properties make it suitable for a wide range of applications in fields such as manufacturing, research, and healthcare. In this research we propose two Al-graded Electron Blocking Layer (EBL) and quantum barriers (QBs) to improve the performance of AlGaN-based Deep UV-LDs. The electrical properties and optical properties of three structures containing conventional EBL, composition graded increased EBL, and liner graded increased of EBL and QBs were numerically investigated. It was found that the structure-C with linear graded increased EBL and QBs significantly improved the Optical Confinement Factor (OCF) 21%, gain 1600 cm-1, emission power 0.060 W, raised the carrier concentration in the MQWs region, enhanced the stimulated recombination rate and reduced the carrier leakage, of the laser diode (LDs). But at a 100-mA injection current, the threshold current and voltage were reduced to 43 mA and 5.00 V, valance barrier height 270 meV respectively. In compare to the conventional structure, introducing a graded design for both EBL and Quantum Barriers (QBs) with increased aluminum content significantly enhanced the performance of the laser diode (LD). This improvement is essential for advancing Deep Ultraviolet Laser Diodes (DUV-LD) technology. [ABSTRACT FROM AUTHOR]

The topology of Hilbert space in semiconductor quantum wells (QW) can become non-trivial when excited by an electromagnetic wave. It means the quasi-energy bands acquire a nonzero integer Floquet-Chern number even if QW is trivial in the equilibrium. We analyze electron-photon interaction in the Floquet state and identify dynamical quantum phases characterized by half-quantized Floquet-Chern numbers. The non-integer topology depends on which equilibrium state is exposed to illumination. Trivial III-V semiconductor QW's such as AlGaAs and AlGaN, being resonantly illuminated, generate the dynamical index | C F | = 1 / 2 , similar to a gapless quantum anomalous semimetal (QAS) in equilibrium. Excitation of 2D topological insulator CdHgTe reveals | C F | = 3 / 2 - the index stemmed exclusively from interaction with chiral photons. Comparing results obtained in continuous and full-Brillouin zone (BZ) models, we conclude that high-momentum regions in BZ contribute to the dynamical half-quantized topology. Results indicate that by manipulating parameters of external force, one can bring inverted-gap QW into a non-equilibrium state with a high topological non-integer charge | C F | = 3 / 2 . We present the phase diagram, which includes all dynamical states of non-trivial topology. • We study topology of Bloch amplitudes under a strong resonance electromagnetic wave by calculating dynamical Chern numbers. • Identify fractional topology caused by a circularly polarized wave. • Present the phase diagram that includes integer and fractional dynamical phases. • Discuss the difference in topology in illuminated AlGaAs (AlGaN) and GdHgTe semiconductor QW's. • Discuss requirements for experimental observation of dynamical topological indexes. [ABSTRACT FROM AUTHOR]

Continued interest in the bioactive alkaloids led to the isolation of five undescribed alkaloids (1–5), ophiorglucidines A-E, and seven known analogues (6–12) from the water-soluble fraction of Ophiorrhiza japonica. The structures were elucidated based on spectroscopic data and quantum calculations as well as X-ray crystallographic analysis. The structure of 1 was characterized as a hexacyclic skeleton including a double bridge linking the indole and the monoterpene moieties, which is the first report of a single crystal with this type of structure. Moreover, the inhibitory effect of zwitterionic indole alkaloid glycosides on xanthine oxidase was found for the first time. The alkaloids 2 and 3 , both of which have a pentacyclic zwitterionic system, were more active than the reference inhibitor, allopurinol (IC 50 = 11.1 μ M) with IC 50 values of 1.0 μ M, and 2.5 μ M, respectively. Structure-activity relationships analyses confirmed that the carbonyl group at C-14 was a key functional group responsible for the inhibitory effects of these alkaloids. [Display omitted] • Five undescribed alkaloids are identified from Ophiorrhiza japonica. • For the first time, the inner salt indole alkaloid glycosides were found to have an inhibitory effect on xanthine oxidase. • The key pharmacophore with inhibitory activity was identified. [ABSTRACT FROM AUTHOR]

[Display omitted] • Morphological evolution analysis of the GaN nanostructure for the preparation of aspect ratio controlled GaN nanorods (NRs). • Investigation of the emission wavelength modulation via growth of three dimensional heterostructure on GaN NRs. • Comprehensive analysis of the color tunability due to aspect ratio regulation via optical and metrological characterization. In the pursuit of developing red, green and blue emitters, comprehension of color tunability in relation to the nanostructure properties is imperative. Hence, we present a systematic study for the fabrication of color tunable emitters based on GaN nanorods (NRs) prepared via two-step etching technique. In the essence of tunable emission wavelength, aspect ratio controlled GaN NRs were employed for the growth of core shell heterostructure of InGaN/GaN multiple quantum wells (MQWs) using MOCVD and the impact of aspect ratio regulation on the emission wavelength modulation was studied. To analyze the role of the GaN NRs aspect ratio in facilitating the tunable emission wavelength, we employed metrological as well as optical characterizations. Photoluminescence spectra results established a direct relation of the aspect ratio to the emission profile of the GaN NRs. Furthermore, power-dependent photoluminescence (PL) and cathodoluminescence (CL) studies clarified the source of the emission, providing confirmation of the active region's exclusive growth on non-polar sidewalls and the absence of polarization-induced fields. Tunneling microscope measurements revealed a direct relation of the GaN NRs aspect ratio to the emission wavelength profile. In conclusion, we studied comprehensively the impact of aspect ratio regulation for the tunable emission wavelength. [ABSTRACT FROM AUTHOR]

In this work, the functioning of the Top-Hat Hot-Electron Light Emission and Lasing in a Semiconductor Heterostructure (TH-HELLISH) structure, which is based on InGaN/GaN multiple quantum wells, is investigated to employ it as an optical amplifier and wavelength converter. The heterojunction structure is formed by placing four InGaN quantum wells in the n-type GaN region between the n- and p-type GaN layers. The device with a TH-HELLISH structure was grown on a sapphire (Al 2 O 3) substrate by Metal-Organic Chemical Vapor Deposition (MOCVD) with an indium ratio of 0.16. The TH-HELLISH device was fabricated in Top-Hat HELLISH (THH) geometry with four independent n- and p-channels contacts to create a non-isotropic potential distribution in the heterojunction. The electro-photoluminescence (E-PL) technique was used to obtain light amplification and the converted wavelength. A 370 nm excitation light is absorbed by the TH-HELLISH device, subsequently leading to the emission at 440 ± 1 nm, which fulfills the role of a wavelength converter. It was also observed that TH-HELLISH operates as an optical amplifier with a 1.6-times increase in emission at 370 nm excitation. When the device is illuminated with a wavelength of 370 nm, it is monitored that the threshold electric field decreased from 0.25 kV/cm to 0.18 kV/cm, accompanied by a corresponding decrease in the threshold voltage from 12.5 V to 9.0 V. In addition, the TH-HELLISH device is found to be operated independently of the polarity of the applied voltage, and the absorption and emission regions of the device can be switched by changing the polarity of the applied voltage, therefore behaving as a bi-directional wavelength converter and optical amplifier. • TH-HELLISH device is investigated to employ it as an optical amplifier and wavelength converter at room temperature. • A 370 nm excitation light is absorbed by the TH-HELLISH device, subsequently leading to the modulation of 440 ± 1 nm light. • It was also observed that TH-HELLISH operates as an optical amplifier with a 1.6-times increase in emission at 370 nm excitation. • It is observed that the threshold electric field decreased when the device is illuminated with a wavelength of 370 nm. [ABSTRACT FROM AUTHOR]

P-AlGaN EBLs are usually used to control the overflow of electrons from the multiple quantum wells (MQWs) in AlGaN-based deep ultraviolet (DUV) edge-emitting laser diodes (EELDs). They're specially designed to prevent the excess flow of electrons from the MQW. This control is essential for maintaining the laser's efficiency and performance. Using optimized parameters of Al composition through theoretical calculations using Crosslight software helps certify the electrically driven EELD functions effectively within the desired operational range. In this study, the traditional p-AlGaN EBL within the electrically driven EELD is substituted with an undoped AlGaN EBL. This modification aims to raise the effective barrier height of the conduction band, and thus effectively stopping the electron leakage while improving the injection of holes. By optimizing the aluminum composition in the current research, efforts are made to lower the threshold current (I th) and elevate the overall enactment of the graded undoped AlGaN EBL EELD. Various structural designs, including both conventional and undoped configurations, have been successfully created and analyzed in this study. Particular attention was given to investigating the impact of grading techniques applied to the electron-blocking layer. The graded undoped AlGaN EBL EELD performed better than the highly doped AlGaN EBL EELD due to the minimized free carrier absorption loss. Specifically, it shows higher slope efficiency (S.E) of 1.45 W/A and a significantly lower I th of 790 mA. A new AlGaN EBL EELD design was tested with different layers. The ones with a graded undoped EBLs performed better than traditional AlGaN EBL EELD, improving power efficiency. The graded undoped EBLs setup also reduced the threshold current compared to traditional AlGaN EBL EELD. • Advanced Doping Strategy: We propose a novel approach to enhance the performance of AlGaN-based deep Ultraviolet (DUV) EELDs by optimizing undoping concentrations in the electron-blocking layer (EBL). • Output Power Breakthrough: Through meticulous design and theoretical calculations using the Lastip software, we achieve a significant increase in the EELD output power and capabilities, marking a remarkable advancement in DUV laser technology. • Ultraviolet Laser Emission: The designed EELD structure demonstrates the successful emission of a class-c ultraviolet laser at an impressive wavelength of 265 nm, opening doors to various applications in fields such as spectroscopy, medical diagnostics, and materials processing. • Effective Conduction Barrier: Our simulation results indicate that the optimized EBL leads to the attainment of an effective conduction band barrier height. This achievement plays a pivotal role in realizing the envisioned enhancements in EELD performance. • Performance Enhancement Factors: The proposed approach promises to deliver higher optical output power, an increased concentration of electrons and holes within MQWs, and a reduction in lasing threshold of the AlGaN based DUV EELDs. [ABSTRACT FROM AUTHOR]

Semiconductor multi quantum well (MQW) design allows for the compression of electron-interaction dimensions, offering advantages for various applications, particularly in nonlinear optics. Despite the potential improvements in nonlinear optical responses, the influence of quantum well periods remains unexplored. In this study, we report the correlation of quantum well periods on the 3rd order nonlinear optical properties in In 0.15 Ga 0.85 N/GaN MQW using z-scan technique under femtosecond and continous wave laser regime. In 0.15 Ga 0.85 N well/GaN barrier with x1, x5, x10, x15 periods were grown by MOCVD technique. Good structural quality of grown MQWs were confirmed via HRTEM imaging, EDS, AFM and XRD. Absorption coefficient from UV-Vis coupled with PL emission spectrum shows systematic response of optical linear properties which provide an insight on the overall band gap structure. Positive nonlinear refraction, n 2 and nonlinear absoprtion, β trends is observed under femtosecond an CW laser albeit differences of one order magnitude in χ 3 value. The increase in χ 3 value is shown to be monotonous with the increasing number of quantum well suggesting that compounding effect took place. This findings indicate the possibility of manipulating and tuning nonlinear reponses of MQW structures leading to improvement in semiconductor design in various areas such as optoelectronics, photonics, solar cell research, as well as quantum information processing. • InGaN/GaN MQWs with different periods (x1, x5, x10, x15) were successfully grown by MOCVD, confirmed by HRTEM and EDS. • AFM reveals surface roughness between 10 to 36 nm, while XRD indicates layer thicknesses of 9 nm for GaN and 3 nm for InGaN. • UV-Vis spectroscopy shows minimum absorption, and photoluminescence analysis reveals band edge emssion at 465 nm. • χ(3) values are measured to be in the order of 10−6 esu and 10−5 esu for femtosecond and CW regime, respectively. • χ(3) values increase linearly with quantum well periods, indicating greater nonlinear optical responses in structures with more quantum wells. [ABSTRACT FROM AUTHOR]

In this study, we investigated the combined effects of structure parameters such as size and geometry, as well as hydrostatic pressure, temperature, and magnetic field on the electronic and optical properties of a double inverse parabolic quantum well within the framework of the effective mass and parabolic band approximations. It is very important to consider the effects of temperature and hydrostatic pressure, especially in practical applications involving quantum wells such as semiconductor devices and optoelectronics. The results obtained are in good agreement with the literature. Understanding how these factors affect the electronic and optical properties of semiconductor heterostructures helps to optimize the performance and stability of devices operating under different environmental conditions. [ABSTRACT FROM AUTHOR]