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Exploring potential two-dimensional monolayers with large photogalvanic effect (PGE) has been of great importance for developing self-powered optoelectronic devices. In this paper, we systematically investigate the generation of PGE photocurrent in chalcogen-based Janus XYZ monolayers (X/Y/Z = S, Se, Te; X ≠ Y ≠ Z) based on non-equilibrium Green's function formalism with density functional theory. The optimized Janus SSeTe, SeSTe, and TeSeS monolayers in the rectangular phase are shown stable and, respectively, possess 1.54, 1.49, and 1.74 eV indirect bandgaps. Illuminated by linearly polarized light, the PGE photocurrent without bias voltage can be collected in both armchair and zigzag directions. Unlike common Janus 2D materials with C3v symmetry, the photocurrent peak values of Janus XYZ monolayers do not come up with certain polarization angles, while the relations can be fitted by Iph = α sin(2θ) + β cos(2θ) + γ at each photon energy. Meanwhile, the maximum photoresponses of Janus SSeTe, SeSTe, and TeSeS monolayers are 2.02, 3.33, and 4.42 a20/photon, respectively. The relatively large PGE photocurrents and complicated polarization relations result from the lower symmetry of Janus XYZ monolayers. Moreover, the specific polarization angles for maximum photoresponses at each photon energy and the ratio between two transport directions are demonstrated, reflecting the anisotropy. Our results theoretically predict a potential Janus monolayer family for self-powered optoelectronic applications. [ABSTRACT FROM AUTHOR]

Nickel-doped β-Ga2O3 crystals were investigated by optical absorption and photoconductivity, revealing Ni-related deep levels. The photoconductivity spectra were fitted using the phenomenological Kopylov and Pikhtin model to identify the energy of the zero-phonon transition (thermal ionization), Franck–Condon shift, and effective phonon energy. The resulting values are compared with the predicted ones by first-principle calculations based on the density functional theory (DFT). An acceptor level (0/−) of 1.9 eV and a donor level (+/0) of 1.1 eV above the valence band minimum are consistently determined for NiGa, which preferentially incorporates on the octahedrally coordinated Ga site. Temperature-dependent resistivity measurements yield a thermal activation energy of ∼2.0 eV that agrees well with the determined Ni acceptor level. Conclusively, Ni is an eminently suitable candidate for compensation doping for producing semi-insulating β-Ga2O3 substrates due to the position of the acceptor level (below and close to the mid-bandgap). [ABSTRACT FROM AUTHOR]

PbTe-based compounds are excellent candidates for the different types of optical detector applications from near to far IR ranges. In the present work, a technology has been developed for the fabrication of Pb 1 − x Sn x Te compositions, doped with In, on a thin amorphous substrate (polyimide). The film preparation was performed by the electron gun evaporation method. The systematic study of structure and transport properties (Hall coefficient and electric conductivity) in the entire temperature range of 10–300 K for Pb 1 − x Sn x Te:In films (x = 0 , 0.1, 0.2) was investigated. It was studied that the photoconductivity of the films in the telecom wavelength range, including kinetics, sensitivity, and noise equivalent power, has been conducted and it discovered persistent photoconductivity for all compositions at the temperature T < 21 K. The results of the work have promising potential to use poly(nano) crystalline Pb 1 − x Sn x Te:In films on an amorphous substrate both for photodetection in the telecom wavelength range and for the creation of all-optical neuromorphic systems, cooled memory, and logic elements operating at the low energy of laser pulses. [ABSTRACT FROM AUTHOR]

This study aims to contribute to the development of theoretical and experimental tools for characterizing the transport properties of perovskite semiconductors. In the context of existing transport characterization methods for perovskites, there is a need for techniques that can accurately assess the critical transport parameters, such as diffusion lengths, given the specific challenges posed, such as their inherent instabilities. The novel methodology employed involves the development of a theoretical model to describe the running fringes-induced photo-electromotive force (RF photo-EMF) effect in bipolar photoconductors with a rather general type of photoconductivity relaxation behaviors for both carriers. This model is founded on the theory of photoinduced space charge grating formation in semiconductors. Subsequently, RF photo-EMF experiments were conducted on methylammonium lead iodide (CH 3 NH 3 PbI 3 or MAPI) polycrystalline films of varying grain sizes. By utilizing the RF photo-EMF technique, we successfully elucidated crucial transport and recombination characteristics, notably the ambipolar diffusion length and relaxation times of the charge carriers. Significantly, the developed theoretical model exhibited a remarkable agreement with the experimental results, highlighting its ability in explaining and predicting the behavior of charge carriers in perovskite semiconductors. The results of this study make a substantial contribution to the field of perovskite semiconductors by offering a novel theoretical and experimental approach to characterization of perovskites' transport properties. [ABSTRACT FROM AUTHOR]

Three sets of heteroepitaxial diamond crystals grown under nominally identical process conditions on Ir/YSZ/Si(001) substrates have been studied with respect to structural defects, chemical purity, and x-ray induced photoconductivity (PC). The dislocation density that varied systematically between 10 7 and 10 9 cm − 2 had a minor influence on dark conductivity and photoconductive gain G. In contrast, the substitutional nitrogen (N N ) and substitutional boron (N B ) defects, which are both present at very low concentrations (≤ 1 ppb), turned out to be the crucial factors controlling the electrical behavior. Small differences between both resulted in variations of the photocurrents by up to 5 orders of magnitude. The maximum in G of 0.75 × 10 4 was measured in the sample with highest dark conductivity. It could be explained conclusively within our model calculations on gain formation by N N ≤ N B . For low gain samples, we found N N > --> N B . However, the measured G values were far from theoretical predictions. This indicates a dominating role of additional traps. After x-ray switch-off, persistent photoconductivity (PPC) was observed in high gain samples. It was attributed to an energetic barrier hampering the recharging of nitrogen atoms by hole capture. As a possible source, strain fields generated by dislocations are suggested. [ABSTRACT FROM AUTHOR]

Topological materials occupy an important place in the quantum materials family due to their peculiar low‐energy electrodynamics, hosting emergent magneto‐electrical, and nonlinear optical responses. This manuscript reports on the optical responses for the magnetic topological nodal semimetal Co2MnGa, studied in a thin film geometry at various thicknesses. The thickness‐dependent optical conductivity is investigated, observing a substantial dependence of the electronic band structure on thickness. Additionally, details on the ultrafast response of the low energy excitations in the terahertz frequency are reported by employing optical pump‐terahertz probe (OPTP) spectroscopy. In particular, the photocarrier dynamics of Co2MnGa thin films is studied at varying pump fluence, pump wavelength, and film thickness, observing a negative THz photoconductivity which is assigned to a dynamical formation of large polarons in the material. [ABSTRACT FROM AUTHOR]

The measurement and description of the charge-carrier lifetime ( τ c ) is crucial for the wide-ranging applications of lead-halide perovskites. We present time-resolved microwave-detected photoconductivity decay (TRMCD) measurements and a detailed analysis of the possible recombination mechanisms including trap-assisted, radiative, and Auger recombination. We prove that performing injection-dependent measurement is crucial in identifying the recombination mechanism. We present temperature and injection level dependent measurements in CsPbBr3, which is the most common inorganic lead-halide perovskite. In this material, we observe the dominance of charge-carrier trapping, which results in ultra-long charge-carrier lifetimes. Although charge trapping can limit the effectiveness of materials in photovoltaic applications, it also offers significant advantages for various alternative uses, including delayed and persistent photodetection, charge-trap memory, afterglow light-emitting diodes, quantum information storage, and photocatalytic activity. [ABSTRACT FROM AUTHOR]

Two-dimensional platinum diselenide (PtSe2) has been explored for applications in visible and infrared photodetectors, owing to its tunable electrical and optoelectronic properties governed by layer-dependent bandgaps. Studies have explored both positive photoconductivity (PPC) and negative photoconductivity (NPC) behaviors in few-layer PtSe2 thin films, proposing mechanisms related to gas molecule adsorption. However, these proposed mechanisms, typically based on models with ideal limit structures, often lacked consistency with the structure and scale of polycrystalline thin films employed in actual experiments. Here, photodetectors utilizing monolayer PtSe2 ribbons were designed, demonstrating a significant NPC effect upon exposure to visible light in atmospheric conditions, with device resistance increasing to over threefold the initial state. Under vacuum conditions, the device demonstrated PPC characteristics. Density functional theory calculations indicated that oxygen molecules physically adsorbed at the edges of PtSe2 ribbons were integral. Laser irradiation prompted the detachment of oxygen molecules from the ribbon's edges, leading to a decreased carrier concentration in channel conductivity. The abundant edge sites of the ribbons endowed the photodetectors with a pronounced NPC response. This study diverted from traditional multilayer PtSe2 films to explore monolayer PtSe2 ribbons. These ribbons, as limit structures, offered a more fundamental insight into the intrinsic photoconductivity properties of PtSe2. Photodetectors employing PtSe2 ribbons presented novel application prospects in low-power photodetection, gas detection, and additional fields. [ABSTRACT FROM AUTHOR]

This study is based on density functional theory, studied structure and electronic properties, optical properties, electrocatalytic water splitting to produce H 2 , and electrical properties of the WS 2 /Ga 2 O 3 heterojunction. By analyzing the photoelectric characteristics, we find that the WS 2 /Ga 2 O 3 heterojunction has built-in electric field, which can separate photogenerated carriers and effectively capture visible light for visible light photocatalysis. In addition, the change of Gibb free energy (Δ G) tends to 0, so when the WS 2 /Ga 2 O 3 heterojunction is used as a catalyst, the hydrogen evolution reaction tends to proceed spontaneously. Interestingly, by analyzing the electrical properties, we find that the large and obviously changed photogalvanic effect photocurrent is produced with the change of polarization angle and photon energy of the WS 2 /Ga 2 O 3 heterojunction, and it has the potential to become high-sensitivity optoelectronic detector. • The WS 2 /Ga 2 O 3 heterojunction has excellent electrocatalytic hydrogen production performance. • The WS 2 /Ga 2 O 3 heterojunction has obvious absorption peak in visible and infrared regions. • The PGE photocurrent of the WS 2 /Ga 2 O 3 heterojunction reaches 2.12 a 0 2/photon in the armchair direction. [ABSTRACT FROM AUTHOR]

The ultrafast dynamics of photoexcited charge carriers are studied in micron‐scale crystals composed of the inorganic perovskite CsPbBr3 with time‐resolved terahertz spectroscopy. Exciting with photon energy close to the band edge, it is found that a fast (<10 ps) decay emerges in the terahertz photoconductivity with increasing pump fluence and decreasing temperature, dominating the dynamics at 4 K. The fluence‐dependent dynamics can be globally fit by a nonlinear recombination model, which reveals that the influence of different nonlinear recombination mechanisms in the studied pump fluence range depends on temperature. Whereas the Auger scattering rate decreases with decreasing temperature from 77 to 4 K, the radiative recombination rate increases by three orders of magnitude. Spectroscopically, the terahertz photoconductivity resembles a Drude response at all delays, yet an additional Lorentz component due to an above‐bandwidth resonance is needed to fully reproduce the data. [ABSTRACT FROM AUTHOR]

The photogalvanic effect (PGE) in Weyl semimetals, such as WTe2 and MoTe2, has been widely observed and is considered a promising phenomenon for advancing Weyl semimetal-based optoelectronic devices. However, as device dimensions continue to shrink, edge effects on photocurrent generation and modulation become increasingly significant and cannot be overlooked. Herein, we have discovered a locally enhanced edge linear photogalvanic effect at the edge of WTe2 thin-film devices using a home-built polarization-modulated scanning photocurrent system, which arises from symmetry breaking. Furthermore, the magnitude and direction of this edge photocurrent are modulated by the polarization direction of the incident light. This research provides valuable insights for the development of polarization-sensitive photodetectors based on layered type-II Weyl semimetals. [ABSTRACT FROM AUTHOR]

AgIn5S8, a narrow, direct bandgap semiconductor, has gained much attention in photocatalysis due to its excellent visible-light absorption coefficient, good photoconductivity, light stability and biocompatibility. Thus, it is a promising active material for photocatalytic degradation of organic pollutants. In this review, synthesis methods of different AgIn5S8-based photocatalysts are introduced in detail first, such as solid-state reaction methods, hydrothermal/solvothermal methods, and microwave synthesis methods. Subsequently, photocatalytic degradation improvement strategies of AgIn5S8-based photocatalysts are systematically summarized, mainly including morphology control, defect engineering, doping, surface plasmon resonance effects and constructing heterojunctions. The perspective and the future challenge are provided at the end. This review can accelerate the development of AgIn5S8-based photocatalysts in related applications. [ABSTRACT FROM AUTHOR]

To better understand the variations in physical, mechanical, and electrical properties, (Ge 2 S 8) 100-x Te x chalcogenide glasses have been synthesized. These glasses encompass a composition range of 0 ≤ x ≤ 12. The mechanical properties have been studied by determining the longitudinal (ν L) and transverse (ν T) ultrasonic velocities. A network structure evaluation with composition has been performed via parameters like coordination number (< N r >), crosslinking density (D CL), glass transition temperature (T g), etc. Also, the elastic parameters trend values have been associated with the decrease in the cohesive energy value of the system. An overall physical analysis of the Ge-S-Te systems reveals that the system's rigidity and the cross-linking density are decreasing. Within the temperature range of 300–420 K, the temperature dependency of the dark conductivity and photoconductivity has been investigated. The intensity-dependent photoconductivity is governed by a power law, with intensity (I ph = G δ ) with δ lying between 0.5 and 1. The photosensitivity values reveal that the glassy system may be suitable for applications in optoelectronic devices. A correlation among the parameters has been established by calculating elastic parameters and conductivity measurements and evaluating the network structure theoretically. The present efforts clarify the composition-structure dependence and relationship in the Ge-S-Te glass series. [ABSTRACT FROM AUTHOR]

The photogalvanic effect (PGE) in Weyl semimetals, such as WTe2 and MoTe2, has been widely observed and is considered a promising phenomenon for advancing Weyl semimetal-based optoelectronic devices. However, as device dimensions continue to shrink, edge effects on photocurrent generation and modulation become increasingly significant and cannot be overlooked. Herein, we have discovered a locally enhanced edge linear photogalvanic effect at the edge of WTe2 thin-film devices using a home-built polarization-modulated scanning photocurrent system, which arises from symmetry breaking. Furthermore, the magnitude and direction of this edge photocurrent are modulated by the polarization direction of the incident light. This research provides valuable insights for the development of polarization-sensitive photodetectors based on layered type-II Weyl semimetals. [ABSTRACT FROM AUTHOR]

The electrochemical polymerization of 3,4-ethylenedioxythiophene in the presence of a water-soluble Na+-containing fullerene with hydroxyl groups is studied. The monitoring of the electrosynthesis process by spectroscopic methods shows that during the polymerization of 3,4-ethylenedioxythiophene, fullerenol incorporates into the film composition, regardless of the fullerenol concentration used. The electronic structure, morphology, spectroelectrochemical and electrochemical properties, and near-IR photoconductivity of the poly-3,4-ethylenedioxythiophene–fullerenol composite films are studied for the first time. A mechanism of photoconductivity is proposed, related to the fact that during the photoexcitation of the composite, the electron transfer from the polaron (bipolaron) state of poly-3,4-ethylenedioxythiophene to the LUMO level of fullerenol increases the concentration of photogenerated charge carriers. [ABSTRACT FROM AUTHOR]

Through precise band engineering, Van der Waals heterostructures integration holds great promise for advancing high‐performance optoelectronic devices, especially photodetectors. This study presents self‐sustaining, dual‐polarity, high photo‐responsive heterostrutures (HS) photodetectors based on Sb2Se3, specifically Bi2Se3/Sb2Se3 and ZnSe/Sb2Se3. The Bi2Se3 (ZnSe) layer functions as a channel in a reconfigurable HS phototransistor configuration. These HS devices demonstrate a negative photoconductive response with bias‐modulated polarity switching of the photocurrent. The Bi2Se3/Sb2Se3 device exhibits a responsivity switch from −4 mA W−1 to 0.14 A W−1, while the ZnSe/Sb2Se3 device shows a substantially enhanced responsivity switch from ‐400 mA W−1 to 12 A W−1. This negative photo response results from a photoinduced carrier trapping mechanism at the interface of the channel layer and photosensitizer material. The bias modulation enables the switching from negative to positive responsivity. A comprehensive investigation of photoconductivity modulation provides a deeper understanding of the impact of the photogating effect and trap states under applied bias conditions. Ultrafast transient spectroscopy supports these findings, offering insights into the dynamics of charge carrier relaxation mechanisms and the trapping of photoexcited carriers in defect states, crucial for explaining the dual polarity photo response. These devices present significant advantages for switchable light imaging, optical communication, memory devices, convolution processing, and logic circuits. [ABSTRACT FROM AUTHOR]

In this research, we have conducted an in-depth investigation into the structural, electronic characteristics, and thermodynamic properties of the LiTi2O4 compound using first-principles calculations grounded in density functional theory with the generalized gradient approximation. Our findings reveal that the LiTi2O4 compound possesses a calculated lattice constant of 8.407 Å. Furthermore, we have derived critical battery-related properties, including an average voltage of 1.53 V versus Li/Li+ and an energy density of 245 Wh/kg. To deepen our understanding of LiTi2O4, we have explored its thermodynamic properties employing the quasi-harmonic Debye model. These properties encompass the Debye temperature, volume variation, compressibility modulus, specific capacity, and thermal capacity. Importantly, we have observed that the Debye stiffness of LiTi2O4 increases with rising pressure. Moreover, we have conducted measurements to assess various optical properties of the LiTi2O4 compound. These properties include the absorption coefficient, photoconductivity, and reflectivity. [ABSTRACT FROM AUTHOR]

Co2MnGe (CMG) has been demonstrated recently as a half-metallic ferromagnetic Heusler alloy, which possesses a topologically non-trivial band structure. This behavior is unique to such systems and hence warrants extensive experimental exploration for potential spintronic and chirality sensitive optoelectronic applications. Here, we demonstrate that an epitaxial thin film of CMG acts as a source of terahertz (THz) radiation upon photoexcitation by optical femtosecond laser pulses. Detailed experiments have revealed that a large contribution to THz emission occurs due to nonmagnetic or spin-independent origin; however, a significant contribution in the THz generation is evidenced through an excitation light helicity-dependent circular photogalvanic effect confirming the presence of topologically non-trivial carriers in the epitaxial CMG thin films. Furthermore, we show that not only the topological contribution is easily suppressed but also the overall THz generation efficiency is also affected adversely for the epitaxial films grown at high substrate temperatures. [ABSTRACT FROM AUTHOR]

Currently, there is a great demand for non‐toxic lead‐free halide perovskites as active materials for solar cells, light‐emitting diodes and other optoelectronic devices. Although an essential progress has been made using tin(II) halide perovskites, still greater efforts are needed to improve their stability and manufacture films and devices under a scalable technology. The first goal of the work is to achieve suitable physical properties of 2D Sn(II) polycrystalline perovskite films obtained by the industrially scalable inkjet printing deposition technique. In the present work, inks of 2D tin(II) halide perovskite 2‐thiopheneethylammonium tin(II) iodide, TEA2SnI4, have been successfully formulated in DMF (toxic) and DMSO (non‐toxic) solutions and using appropriate additives (SnF2 and reducing agents) for improving the stability of the inks and the resulting films. Room‐ and low‐temperature excitonic photoluminescence (PL), charge carrier recombination dynamics and µ‐PL is used to explain the observed two excitonic bands, which are associated to the bulk and edges of perovskite grains nanoplatelet‐like composing the polycrystalline films. Promising electro‐optical properties are also obtained in the TEA2SnI4 films inkjet‐printed from DMSO formulations onto ITO‐interdigitated electrodes, such as low dark currents, ≈10 – 20 nA at 10 V of bias voltage, and high responsivities ≈1–20 A/W. [ABSTRACT FROM AUTHOR]

Neuromorphic device that percepts ultraviolet (UV) radiations is essential for supplementing human visual perception. However, UV‐responsive synapses with high sensitivity and wavelength selectivity have not yet been developed so far. Herein, 2D optoelectronic synapses that are able to distinguish between UV‐A, UV‐,B and UV‐C radiations using a single material are demonstrated. The synapses use Ca2Nb3O10 nanosheets with wide bandgap and persistent photoconductivity effect (PPC) as UV‐responsive layer. The devices can detect UV‐C rays at ultralow intensity of 70 nW cm−2, which is the lowest record among 2D UV synaptic devices. Moreover, such a device demonstrates UV image vision, recognition, and memorization functions based on its diverse synaptic behaviors. The atomically thin UV synapses provide implications for enhancing human visual perception capabilities with spectral selectivity, ultrahigh sensitivity, and low‐energy consumption. [ABSTRACT FROM AUTHOR]

This study investigates the impact of spin-coating speed on the performance of carbon nanotube (CNT)-based optoelectronic synaptic devices, focusing on their long-term memory properties. CNT films fabricated at lower spin speeds exhibited a greater thickness and density compared to those at higher speeds. These denser films showed enhanced persistent photoconductivity, resulting in higher excitatory postsynaptic currents (EPSCs) and the prolonged retention of memory states after UV stimulation. Devices coated at a lower spin-coating speed of 2000 RPM maintained EPSCs above 70% for 3600 s, outperforming their higher-speed counterparts in long-term memory retention. Additionally, the study demonstrated that the learning efficiency improved with repeated UV stimulation, with fewer pulses needed to achieve the maximum EPSC in successive learning cycles. These findings highlight that optimizing spin-coating speeds can significantly enhance the performance of CNT-based synaptic devices, making them suitable for applications in neuromorphic computing and artificial neural networks requiring robust memory retention and efficient learning. [ABSTRACT FROM AUTHOR]

Ferroelectric field effect transistors (FeFETs), characterized by their low power consumption and polarization effect, can be employed in photodetectors based on 2D materials. In this paper, a MoS2 phototransistor with epitaxial ferroelectric (Hf0.5Zr0.5)O2 (HZO) is reported as a gate dielectric layer. Gate‐dielectric‐polarization‐dependent ambipolar behavior is observed in the FET, and relatively low power consumption and hysteresis‐free loop are achieved in the FeFET. The anomalous negative photoconductivity (NPC) is observed as well. Possible reasons for such phenomenon are clarified including the photogating effect originating from the interface traps and the polarization‐dependent electric‐field control through ferroelectric gating. The high responsivity of −8.44 × 103 A W−1 in the negative photoconductivity as well as the response time of 500 ms are reported. The demonstrated Molybdenum disulfide (MoS2) FeFET photodetectors show great potential in the on‐chip complementary metal‐oxide semiconductor (CMOS)‐compatible circuits for multifunctional devices. [ABSTRACT FROM AUTHOR]

We present a study of the structural features of polycrystalline a diamond film (PCDF) synthesized by the microwave plasma-enhanced chemical vapor deposition method from a hydrogen/pentane mixture and consider its photoelectric response to synchrotron radiation. Raman spectroscopy analysis of the PCDF cross-section revealed the presence of sp2-hybridized inclusions. As the distance from the PCDF growth surface increases, the amount of the non-diamond phase also increases, while its morphology changes from amorphous to crystalline graphite-like carbon. The investigation of the photoelectric response of PCDF was carried out at the "Cosmos" station using synchrotron radiation from the VEPP-4M storage ring. The PCDF detector exhibited maximum sensitivity at low bias voltage. This effect was attributed to the increased efficiency of collecting photo-induced charge carriers from the diamond to the sp2-hybridized inclusions followed by their subsequent transport through conductive paths along the boundaries between diamond crystallites. [ABSTRACT FROM AUTHOR]

Understanding the recombination lifetime of charge carriers (τc$\left(\tau\right)_{\text{c}}$) is essential for the diverse applications of photovoltaic materials, such as perovskites. The study on the inorganic perovskite, CsPbBr3, reveals recombination dynamics exceeding 1 ms below 200 K and τc$\left(\tau\right)_{\text{c}}$ approaching 100 μs at room temperature. Utilizing time‐resolved microwave‐detected photoconductivity decay in conjunction with injection dependence, it is found that τc$\left(\tau\right)_{\text{c}}$ is dominated by impurity charge trapping. The observed injection dependence is well corroborated by modeling of the trap mechanism. The ultralong decay time is also consistent with photoconductivity measurements with a continuous‐wave excitation at powers corresponding to around 1 Sun irradiation. While charge‐carrier trapping may, in theory, impose limitations on the photovoltaic efficiency of single‐cell devices, it can also contribute to increased efficiency in tandem cells and find applications in photodetection, photocatalysis, and quantum information storage. [ABSTRACT FROM AUTHOR]

The basic idea of this study is based on the hypothesis that it is possible to obtain nanostructures by stimulating local chemical reactions. Starting with this hypothesis we assumed that it is possible to disperse some inorganic agent into the epoxy resin and stimulating the mixtures we could get some nano-structures what are changing the basic electric behaviour of the polymer matrix. We dissolved some metallic chlorides in DMF (dimethylformamide) and we mixed together the solution with the epoxy resin (the main component). Applying various external stimuli we get materials showing various properties, different from the epoxy resin properties. The electric photoconductivity is increased (in some cases) but the mechanical properties are damaged due the solvent presence into the polymer matrix. [ABSTRACT FROM AUTHOR]

This study describes the fabrication of hybrid two-dimensional (2D)-quantum dot (QD) MoS2–AgInS2 photoconductive devices through the mechanical pressing of a MoS2 flake onto an AgInS2 QD film. The devices exhibit an enhanced photoresponse at both continuous and modulated optical excitations, compared with the bare MoS2 or AgInS2 layer, due to the formation of a built-in electric field near the MoS2/AgInS2 interface. The continuous wave photoresponse is significantly higher due to the effective photoconductive gain when electrons flow freely through the MoS2 flake, whereas holes are effectively trapped in AgInS2 QDs. The study highlights the potential of hybrid 2D-QD MoS2–AgInS2 devices for photovoltaic and optoelectronic applications. [ABSTRACT FROM AUTHOR]

This research investigates the effects of barium (Ba) doping the photoelectric properties of zinc oxide (ZnO) nanoparticles (NPs) to explore their potential applications in optoelectronic devices.Photocurrent experiments reveal intriguing negative photoconductivity (NPC) behavior in Ba:ZnO based UV photodetectors (PDs).Moreover, the exploration of UV PD performance reveals rise and fall times of approximately 8.26s and 8.72s, respectively, under a -1V external bias.Our fabricated device shows higher detectivity about 1.33 × 10 16 Jones and external quantum efficiency exceeding 100 %, compared to other PD. The analysis of transient currentsuggests the existence of two kinds of defects contributing to NPC. Through an investigation of the noise density, exponents γ ranging between −2.048 and −1.76 were determined, substantiating the hypothesis that the observed noise originates from a distribution of defects. Overall, these results underscore the potential of Ba:ZnO NPs for high-performance devices compared to conventional ZnO-based PDs. [ABSTRACT FROM AUTHOR]

In this study, undoped hydrogenated amorphous silicon (a-Si:H) thin films deposited under moderate dilution ratios of silane by radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD) have been investigated using steady-state photoconductivity and improved dual beam photoconductivity (DBP) methods to identify changes in multiple gap states in annealed and light-soaked states. Four different gap states were identified in annealed state named as A, B, C, and X states. The peak energy positions of these Gaussian distributions are consistent with those recently identified by Fourier transform photocurrent spectroscopy (FTPS). After in situ light soaking, their density increases with different rates as peak energy positions and half-widths remain unaffected. The electron-occupied A and B states located below the dark Fermi level and their density and ratios in the annealed and light-soaked states correlate well with those defects detected by time-domain pulsed electron paramagnetic resonance (EPR) experiments. The A, B, and X states located closer to the middle of the bandgap anneal out at room temperature in dark and define the "fast" states. However, the C states show no sign of room temperature annealing such that they must define the "slow" states in undoped a-Si:H. The results found in this study indicate that the anisotropic disordered network is a more appropriate model than previously proposed defect models based on the continuous random network to define the nanostructure of undoped a-Si:H, where multiple defects, D0 and non-D0 defects, can be identified by using the improved DBP method. [ABSTRACT FROM AUTHOR]

In this work the mechanism of current flow during illumination with hν≥Eg in the temperature range of 77÷300 K is considered. It is established that in the PtSi – Si-M structure in the temperature range of 77÷270 K the regime of space charge limited currents (SCLC) is realized. The current-voltage characteristics of the structures show areas of linear and quadratic dependences of current on voltage, as well as areas of a sharp increase in current. These features of the current-voltage characteristic are explained by the presence of deep level structures and sticking levels for charge carriers in the base region. From the temperature dependence of the SCLC, the concentration of adhesion levels was determined to be equal to (1.8÷3) 1015 cm-3 and the adhesion factor to be equal to 6.32·10-2. In the temperature range 77÷115 K at voltages 0.2÷1 V, the current-voltage characteristic obeys the law J ~ Un(n=3÷4), and above U – the law J ~ U6, followed by a transition to the quadratic law.

Device‐quality Sn‐doped ZnO thin films are obtained from a simple and cost‐effective successive ionic layer adsorption and reaction method with doping concentrations of 1, 3, 5, and 7 mol%. The influence of doping on the structural, morphological, and optoelectronic properties is studied. All the samples show a hexagonal wurtzite structure with planes that reorient themselves upon doping. Morphological studies reveal sharp cone‐like structures branching out to become florets upon doping, resulting in a higher surface‐to‐volume ratio that is reflected in the photoresponse characteristics. The optical properties show a sharp absorbance edge, in the near‐UV region, for all the samples. The calculated bandgap is in the range of 3.19–3.23 eV. Photoluminescence spectra are recorded to analyze the defect states in the samples, and the native defects of ZnO are found. A remarkable increase in current is observed upon illumination indicating significant photoresponse. ZnO tends to show persistent photoconductivity wherein there is delayed decay in the photocurrent. This phenomenon is reduced significantly herein by doping with Sn atoms. The spectral response study confirms that the devices are suitable for visible‐blind, near‐UV detection. [ABSTRACT FROM AUTHOR]

Ga2O3 photodetectors with demonstrated high sensitivity provide a potential subversive scheme for solar‐blind photodetection. However, the planar structure and the relatively slow response speed of the device have restricted the integration and application of Ga2O3 photodetectors. Herein, a narrow SiO2 barrier layer is introduced on the commercial SiC substrate, and a vertical photodetector is realized based on β‐Ga2O3/SiO2/SiC heterostructure with controllable tunneling effect by tailoring the band structure at the interface. The developed device exhibits unconventional rectification characteristics and photoresponse performance in different biasing modes owing to the controllable tunneling effect at the interface. In particular, the photodetector achieves a high responsivity (186.8 A W−1) under solar‐blind illumination at reverse bias, while exhibiting obvious advantages in dark current (3 pA), photo‐to‐dark current ratio (8.8 × 106), linear dynamic range (138.8 dB), and specific detectivity (1.4 × 1015 Jones) at forward bias. The photodetector also demonstrates excellent photoresponse stability after 6 months in air without encapsulation. In addition, an alternating biasing strategy, inspired by its bidirectional operability, is proposed to suppress the persistent photoconductivity effect and increase the decay speed by 1.23 × 105 times. This work provides a referable strategy for the further development of high‐performance Ga2O3‐based photoelectronics. [ABSTRACT FROM AUTHOR]

The fundamental properties of indium phosphide (InP) doped with tellurium and, subsequently, compensated with copper are considered. Data are presented on the existence of four qualitative patterns of the empirical photoconductivity (PC) spectra of InP:Cu in its own region. Works with semiempirical approximation of the PC of sensitive InP:Cu samples are indicated. It is noted that the PC of IP(α()) was analytically approximated as a function of the experimentally obtained spectral dependence of the absorption coefficient of InP. Five approximating functions are proposed in order to obtain an analytical dependence of the absorption coefficient of InP α(). Five dependencies with different values of the standard deviation are obtained. Based on the analytical dependencies, the complete analytical dependence of IP(α()) is modeled. Similarly, five dependencies are obtained, characterized by the corresponding value of the standard deviation. Five nonstationary PC surfaces of IP (as a function of two variables: absorption coefficient, as a function of photon energy, and sample exposure time under normal conditions) are constructed. A conclusion is made about the choice of the most mathematically accurate and physically meaningful approximating function α(). Accordingly, it is shown that this dependence is optimal for obtaining based on it (including this dependence in the structure of IP = f(α) and α = f()) a complete analytical description of the PC process. It is shown that subsequent studies can be aimed at explaining the physical bases of PC in the short-wave region of the fundamental transitions of InP and studying methods of influencing the surface layer of InP:Cu, with the aim of sensitizing and stabilizing it. [ABSTRACT FROM AUTHOR]

Using a first-principles theoretical approach based on the non-equilibrium Green's function formalism of density functional theory, we have investigated the linear photogalvanic effect and circular photogalvanic effect in monolayer MoSSe nanoribbons under different doping cases: pure MoSSe, Se-vacancy (VSe), S-vacancy (VSe), SSe-transposed (TSSe), Se-substituted S (SeS), and S-substituted Se (SSe). Our results demonstrate that doping reduces the spatial inversion symmetry of monolayer MoSSe, resulting in a significant increase in the photocurrent of the doped system and higher polarization sensitivity. Furthermore, we observed that the armchair direction exhibits a significantly stronger response to linearly polarized light than the zigzag direction, which is more sensitive to circularly polarized light. These findings indicate the wide range of promising applications of 2D MoSSe monolayers, such as in photodetection. [ABSTRACT FROM AUTHOR]

The influence of ionic‐electronic coupling on the electrical conductivity and the photoconductivity of organic mixed ionic electronic conductor (OMIECs) of polyaniline/poly (4‐styrene sulfonic acid) (PANI/PSS) composite films. PANI/PSS composite films are connected by blending the carbon atoms within the aromatic ring in PANI with sulfonate groups in PSS. The electrical conductivity of PANI/PSS composite film increases from 0.80S.cm−1 to 1.23S.cm−1 as the pH value increases from 3 to 9. The electrical conductivity of PANI/PSS composite films for all pH values increases continuously as the temperature increases. Additionally, the PANI/PSS composite films exhibit photo responses at UV light since the band structure can absorb the light in this region. The photoconductivity curves of PANI/PSS composite films for different pH values exhibit good consistency and repeatability. Modeling raising photoconductivity and decaying conductivity after light off leads us to understand the underlying physics of the ionic‐electronic coupling and other parameters on the photoconductivity of OMIECs, consequently building OMIEC devices for different photoconductivity applications. [ABSTRACT FROM AUTHOR]

We have studied the variations in the temperature-dependent absorption edge of a bulk InSe-layered semiconductor using photoconductivity (PC) measurements. From both the X-ray diffraction (XRD) and Raman experimental results, the structural phase of the as-prepared InSe sample was confirmed to be γ-polytype. Upon heating from 15 K to 300 K, the absorption edge of PC spectra was found to shift significantly toward lower energy, and the absorption edge as a function of temperature was further analyzed by the Varshni's relationship and Bose–Einstein empirical equation. The Urbach energy as a function of temperature was obtained by fitting the absorption tail below the absorption coefficient of the PC spectrum, and the effective phonon energy can be derived from the temperature-dependent steepness parameter associated with Urbach energy. Our study indicates that the broadening of the absorption edge in the as-synthesized bulk γ-InSe is caused by a combination of electron/exciton–phonon interactions and thermal/structural disorder. [ABSTRACT FROM AUTHOR]

A study work plan has been put up for methodical work in the field of solar energy photogalvanic (PG) cells. It was suggested and required to do experiments with PG cells in sunlight conditions. Improving the conversion of solar energy (SE) into electricity and storing it in PG cell is the goal of our study. Many characteristics of a PG cell with an MG+D-Xylose+Brij-35 system was investigated. The open circuit voltage (Voc), voltage at dark, photopotential (PP), and photocurrent (PC) recorded in this investigation are 1076.00 mV, 163.00 mV, 913.00 mV, and 673.00 μA, respectively. Through the adjustment of PG cells' numerous parameters, the effects of solar energy were investigated. Based on the aforementioned results, surfactant (Brij-35) have demonstrated through experimentation that they are an effective system and should be further investigated, particularly with regard to improving solar energy output and storage. [ABSTRACT FROM AUTHOR]

Generating fully spin‐polarized currents (FSPC) and pure spin currents (PSC) are of great importance for spintronics. Half‐metallic ferromagnets, which generate 100% spin polarization, are considered as one of the most promising materials for applications in spintronics. However, the knowledge of intrinsic half‐metallic materials in the spin‐dependent photogalvanic effect is still poorly understood. Using first‐principle transport calculations, a robust approach is introduced to obtain FSPC and PSC by spin‐dependent photogalvanic effect in intrinsic half‐metallic materials. Based on the recently synthesized monolayer half‐metallic C(CN)3, a 2D spin photogalvanic device is built and it is demonstrated that the FSPC can be achieved in a wider photon energy range under both linearly and elliptically polarized light due to the half‐metallicity. It is intriguing to note that the device can be easily manipulated to transition between two modes: one for generating FSPC and another for generating PSC by setting the two leads in anti‐parallel configurations. Furthermore, a significant spin‐valve effect can be attained across various photon energies for both linearly and elliptically polarized light. The research shows that half‐metallic materials are an ideal platform for studying and generating FSPC and PSC, which presents a remarkable avenue for the development of advanced spintronic devices in the next generation. [ABSTRACT FROM AUTHOR]

Self‐powered photodetectors with dual‐polarity response have great advantages in processing complex light information that is proven to be applied in switchable light imaging, optical communication, and spectral band distinction. Here, a novel strategy for designing self‐powered photodetectors by introducing the double symmetric Schottky junctions at the semiconductor‐metal interfaces is proposed, which guarantees the linear response characteristic and dominates the transfer of photogenerated carriers without external bias. Narrow bandgap semiconductor SnTe is employed as the photosensitive material. The bandgap is characterized to be 126 meV, showing great potential for wide spectrum response. As the consequence of selective excitation of unilateral Schottky junction and switching of electric field polarity, the device obtains a dual‐polarity photoresponse, which can be tuned from −14.8 to 13.5 µV. Moreover, an ultra‐broadband photoresponse from near‐infrared 808 nm to far infrared 10.6 µm is achieved with deep exploration of the working mechanism. The synergistic effect of photo thermoelectricity and photoconductivity created a high photoresponsivity of 0.35 mV W−1 excited by 10.6 µm at room temperature. This work provides a novel design strategy for self‐powered photodetectors with a dual‐polarity powered principle, which can take full advantage of the directivity of the photoresponse to identify optical information. [ABSTRACT FROM AUTHOR]

Developing devices with a wide-temperature range persistent photoconductivity (PPC) and ultra-low power consumption remains a significant challenge for optical synaptic devices used in neuromorphic computing. By harnessing the PPC properties in materials, it can achieve optical storage and neuromorphic computing, surpassing the von Neuman architecture-based systems. However, previous research implemented PPC required additional gate voltages and low temperatures, which need additional energy consumption and PPC cannot be achieved across a wide temperature range. Here, we fabricated a simple heterojunctions using zinc(II)-meso-tetraphenyl porphyrin (ZnTPP) and single-walled carbon nanotubes (SWCNTs). By leveraging the strong binding energy at the heterojunction interface and the unique band structure, the heterojunction achieved PPC over an exceptionally wide temperature range (77 K-400 K). Remarkably, it demonstrated nonvolatile storage for up to 2×104 s, without additional gate voltage. The minimum energy consumption for each synaptic event is as low as 6.5 aJ. Furthermore, we successfully demonstrate the feasibility to manufacture a flexible wafer-scale array utilizing this heterojunction. We applied it to autonomous driving under extreme temperatures and achieved as a high impressive accuracy rate as 94.5%. This tunable and stable wide-temperature PPC capability holds promise for ultra-low-power neuromorphic computing. Devices with a wide-temperature range persistent photoconductivity (PPC) and low power consumption is a challenge for optical synaptic devices in neuromorphic computing. Here, the authors develop a carbon nanotube/porphyrin heterojunction on a flexible array, achieving PPC between 77 K to 400 K. [ABSTRACT FROM AUTHOR]

Transient processes in the photoconductivity of TiS3 single crystals exposed to rectangular light pulses in the wavelength range of λ = 405–940 nm are investigated. It is established that the decay in the photoconductivity after switching the light off at temperatures from 78 to 180 K is described by a logarithmic law in the range from 10–3 to 102 s (i.e., when time changes by five orders of magnitude). This means that the relaxation process is characterized by times ranging, at least, from several tens of microseconds to several tens of minutes. It is shown that the relaxation is basically successive: the recombination barrier increases while the conductivity approaches the equilibrium value. [ABSTRACT FROM AUTHOR]

The bulk photovoltaic effect (BPVE) in non-centrosymmetric materials has attracted significant attention in recent years due to its potential to surpass the Shockley-Queisser limit. Although these materials are strictly constrained by symmetry, progress has been made in artificially reducing symmetry to stimulate BPVE in wider systems. However, the complexity of these techniques has hindered their practical implementation. In this study, we demonstrate a large intrinsic photocurrent response in centrosymmetric topological insulator Ag2Te, attributed to the surface photogalvanic effect (SPGE), which is induced by symmetry reduction of the surface. Through diverse spatially-resolved measurements on specially designed devices, we directly observe that SPGE in Ag2Te arises from the difference between two opposite photocurrent flows generated from the top and bottom surfaces. Acting as an efficient SPGE material, Ag2Te demonstrates robust performance across a wide spectral range from visible to mid-infrared, making it promising for applications in solar cells and mid-infrared detectors. More importantly, SPGE generated on low-symmetric surfaces can potentially be found in various systems, thereby inspiring a broader range of choices for photovoltaic materials. The bulk photovoltaic effect holds promise for various optoelectronic applications, but it is usually restricted to non-centrosymmetric materials operating in the visible range. Here, the authors report a surface photogalvanic effect spanning from visible to midinfrared wavelengths in a centrosymmetric topological insulator, Ag2Te. [ABSTRACT FROM AUTHOR]

The protection of lead halide perovskite within a stable matrix normally leads to the loss of semiconducting properties. Here, we report the synthesis of perovskite‐ZIF glass interpenetrating networks via a cold pressing method, which allows the advantages of bright photoluminescence, high photoconductivity and environmental stability. This hybrid architecture has provided a novel design strategy for the real‐world application of perovskite‐based devices. [ABSTRACT FROM AUTHOR]

In this work, the photoconductivity (PC) spectrum of thin CdSe films was studied. In the course of studies on glass substrates, thin films of cadmium and selenium with a thickness of h = 200 nm and h = 400 nm were selected. The thickness of the samples obtained by chemical deposition was determined by the gravimetric method. Since CdSe crystal is a light-sensitive semiconductor material, the photoconductivity of thin films has been studied. The spectra obtained during studies carried out at a wavelength λ = 600-1100 nm were analyzed. It has been established that the spectrum is chaotic, since in the h = 200 nm layers the phase is not completely formed. In the layers h = 400 nm, a maximum centered at the wavelength λ = 710 nm was recorded. [ABSTRACT FROM AUTHOR]

α‐Ga2O3 is a suitable material for UV‐C optical devices owing to its optical absorption edge wavelength. In this study, α‐Ga2O3 thin films are grown on c‐, a‐, m‐, n‐, and r‐oriented sapphire substrates by mist chemical vapor deposition. Furthermore, their structural fluctuations, Δω$\Delta \omega$ (normal direction of the surface) and Δϕ$\Delta \phi$ (rotational direction on the surface), are examined. As a result, the a‐oriented α‐Ga2O3 thin films exhibit the smallest Δω$\Delta \omega$ and Δϕ$\Delta \phi$. Based on the results of the previous examination, metal–semiconductor–metal (MSM) photodetectors are fabricated using c‐ and a‐oriented α‐Ga2O3 thin films and their photoconducting properties are characterized. Under D2 lamp light illumination, the MSM photodetector using a‐oriented films produces photocurrent four to six times greater than those using c‐oriented films. The visible‐light rejection ratios are 104.9$\left(10\right)^{4.9}$ at 10 V and 105.2 at 24 V. The photoresponsivity is estimated to be 2.2 A W−1 under the illumination of a D2 UV lamp and 24 V bias voltage. In these results, it is suggested that the a‐oriented α‐Ga2O3 thin film exhibits a higher in‐plane carrier mobility than the c‐oriented film. Thus, a‐oriented α‐Ga2O3 films are more suitable than c‐oriented α‐Ga2O3 films for fabricating MSM photodetectors. [ABSTRACT FROM AUTHOR]

As a typical penta two-dimensional material and proposed to be potentially synthesized, in this paper we built a two-probe photodetector based on the penta-BP5 monolayer, and further studied linear and elliptical photogalvanic effects in this device. It was found that produced photocurrents in the BP5 photodetectors mainly show sine relation on double times of the polarized or elliptical angle for the incident light, and the relation can be modulated by the photon energy and polarized angle. Interestingly, due to high asymmetry of the BP5 monolayer, the pristine BP5 photodetector generates very high photocurrents, which are even larger than those including vacancy- and substitution-doping, and this result further proved that asymmetry plays a decisive role in the generation of robust photogalvanic effects, instead of introducing impurities to enhance this effect. Furthermore, the linear photogalvanic effect is stronger than the elliptical photogalvanic effect, and the BP5 photodetectors for the pristine, vacancy- and substitution-doping cases have relatively high extinction ratios showing these BP5 photodetectors are all polarization-sensitive. In conclude, these results manifest great potential applications of the penta-BP5 photodetectors on high performance optoelectronics and nanoelectronic devices. [ABSTRACT FROM AUTHOR]

Nowadays there is considerable interest in the photogalvanic effect in low-dimensional devices. In this work, we built a two-dimensional Bi2C-based photodetector and explored the spin-dependent photogalvanic effect under linearly polarized light and zero-bias conditions which can produce experimentally observable photoelectron flow. It was discovered that by introducing vacancies and substitution-doping into the Bi2C photodetector, the photogalvanic effect could be enhanced by 10–100 times that of a pristine photodetector, which is sufficient to be detected in experiments. Moreover, due to strong spin–orbit interactions, the Bi2C photodetector can produce very high spin polarization, even 100% full spin polarization, and pure spin current at a specific incident angle and photon energy, for example in the Bi1-vacancy Bi2C photodetector. In addition, the photon energy of incident light can regulate the produced spin photocurrent, which shows considerable anisotropy. Our results highlight the potential of the Bi2C photodetector as a versatile device in optoelectronics and spintronics applications. [ABSTRACT FROM AUTHOR]

In this study, we explored the behavior of protonated polyaniline/graphene oxide (PANI‐CSA/GO) nanocomposite films with varying GO concentrations, focusing on the novel phenomenon of explosive percolation. We observed a significant increase in electrical conductivity at the explosive percolation threshold, attributed to the emergence of a percolating metallic pathway. This discovery positions PANI‐CSA/GO films as promising materials for various electronic and electrical engineering applications. Additionally, the films demonstrated consistent and repeatable photoconductivity, showing potential for use in high‐performance UV‐photodetectors, photoactive layers in solar cells, light‐emitting diodes, and energy storage devices. Structural analyses using fourier transform infrared spectroscopy (FTIR) and x‐ray diffraction (XRD) confirmed successful GO incorporation within the PANI‐CSA matrix. Different morphological features were observed depending on the GO volume fraction, with increased GO enhancing thermal stability in the conductive zone. Our findings highlight the immense potential of PANI‐CSA/GO nanocomposite films in advanced electronic applications, emphasizing their novel conductive and photoconductive properties and improved thermal stability. [ABSTRACT FROM AUTHOR]

2D van der Waals heterojunctions (vdWH) have emerged as an attractive platform for the realization of optoelectronic synaptic devices, which are critical for energy‐efficient computing systems. Photogating induced by charge traps at the interfaces indeed results in ultrahigh responsivity and tunable photoconductance. Yet, optical potentiation and depression remain mostly modulated by gate bias, requiring relatively high energy inputs. Thus, advanced all‐optical synapse switching strategies are still needed. In this work, a reversible switching between positive photoconductivity (PPC) and negative photoconductivity (NPC) is achieved in graphene/WSe2 vdWH solely through light‐intensity modulation. Consequently, the graphene/WSe2 synaptic device shows tunable optical potentiation and depression behavior with an ultralow power consumption of 127 aJ. The study further unravels the complex interplay of gate bias and incident light power in determining the sign and magnitude of the photocurrent, showing the critical role of charge trapping and photogating at interfaces. Interestingly, it is found that switching between PPC to NPC can be also obtained at 0 mV drain‐source voltage. Overall, the reversible potentiation/depression effect based on light intensity modulation and its combination with additional gate bias tunability is very appealing for the development of energy‐efficient optical communications and neuromorphic computing. [ABSTRACT FROM AUTHOR]

Sulfur‐coordinated coordination polymers (S−CPs) have unique optoelectrical properties that originate from infinite M−S bond networks. In this study, we synthesized and characterized two polymorphs of a two–dimensional (2D) Pb(II) S−CP with a formula of [Pb(tzdt)(OAc)] (Htzdt=1,3‐thiazolidine‐2‐thione, OAc=acetate). Our findings revealed that the thermodynamic product (KGF‐26) possesses quasi‐2D (−Pb−S−)n layers with weak nonbonded Pb−S bonds, whereas the kinetic product (KGF‐27) has intrinsic 2D (−Pb−S−)n layers with Pb−S bonds. The results of time‐resolved microwave conductivity measurements and first–principles calculations confirmed that KGF‐27 exhibits higher photoconductivity than KGF‐26, which establishes that the inorganic (−Pb−S−)n networks with Pb−S bonds are crucial for achieving high photoconductivity. This is the first experimental demonstration of the impact of the (−M−S−)n networks in S−CPs on photoconductivity through the comparison of crystal polymorphisms. [ABSTRACT FROM AUTHOR]

The microwave photoconductivity of a system of gapless Dirac fermions in HgTe quantum wells with a critical thickness has been experimentally and theoretically investigated. It has been found that the photoconductivity fluctuates depending on the gate voltage near the Dirac point, and the fluctuation amplitude increases with an increase in the conductor size and a decrease in temperature. A theoretical explanation of the microwave response based on the assumption of the existence of a percolation two-dimensional fractal network of helical edge current states induced by fluctuations in the well thickness near the critical value has been proposed. It has been shown that the microwave photoconductivity of this network fluctuates with a change in the Fermi energy and the behavior of the fluctuation amplitude is in qualitative agreement with the corresponding experimental data. [ABSTRACT FROM AUTHOR]