Search

2D conjugated metal–organic frameworks (2D c‐MOFs) are emerging as unique electroactive materials for electronics and spintronics. The structural design and discovery of Kagome‐type 2D c‐MOFs exhibiting a metallic state are of paramount significance, yet remain rarely explored. Here, the solution synthesis of benzenehexol‐based 2D c‐MOFs based is presented on the tetrahydroxy‐1,4‐quinone (THQ) ligand. This study shows that controlling the pH of the reaction system to ≈7.5 yields an energetically favorable nonporous Cu3(C6O6) with a Kagome lattice, while at a pH of ≈10, the known porous Cu3(C6O6)2 with a honeycomb lattice is obtained. The crystal structures of both Cu3(C6O6)2 and Cu3(C6O6) are resolved with near‐atomic precision (resolution, 1.8 Å) using an imaging technique. Unlike the p‐type semiconducting behavior of Cu3(C6O6)2, theoretical studies identify Cu3(C6O6) as a metal due to its unique structural topology. The metallic state of Cu3(C6O6) is experimentally validated by terahertz time‐domain spectroscopy (THz‐TDS), which shows an increase in conductivity upon cooling. Scattering‐type scanning near‐field optical microscopy (s‐SNOM) measurements further support these findings by revealing an increase in normalized reflectivity with decreasing temperature. This work provides a new avenue for tailoring the structural topology of 2D c‐MOFs to attain the Kagome lattice and metallic state. [ABSTRACT FROM AUTHOR]

The isomerization of glucose to fructose is an important process in the conversion of biomass into valuable fuels and chemicals. Development of efficient catalyst for this reaction has attracted much attention. In this study, Sn‐Beta zeolites with rich silanols were synthesized for glucose isomerization by solid‐state ion‐exchange method, where Si‐Beta zeolites with different amounts of silanols were applied as the precursors. It is confirmed that open Sn sites show much higher catalytic performance than closed Sn sites for glucose isomerization (about 2.1 times). The silanol amount in Si‐Beta not only affects the formation of framework Sn sites in Sn‐Beta but also influences the isomerization reaction. More silanols in the catalyst can promote the 1,2‐H shift in isomerization and reduce the side reactions of formation of mannose and C3 products. Over 3Sn‐Beta‐3h with rich silanols, 64 % of fructose yield was obtained. Furthermore, the prepared Sn‐Beta catalyst is stable and recyclable. High fructose yield and facile synthesis method of Sn‐Beta reported in this work will contribute to the development of biomass and sugar industry. [ABSTRACT FROM AUTHOR]

2D magnetic materials hold substantial promise in information storage and neuromorphic device applications. However, achieving a 2D material with high Curie temperature (TC), environmental stability, and multi‐level magnetic states remains a challenge. This is particularly relevant for spintronic devices, which require multi‐level resistance states to enhance memory density and fulfil low power consumption and multi‐functionality. Here, the synthesis of 2D non‐layered triangular and hexagonal magnetite (Fe3O4) nanosheets are proposed with high TC and environmental stability, and demonstrate that the ultrathin triangular nanosheets show broad antiphase boundaries (bAPBs) and sharp antiphase boundaries (sAPBs), which induce multiple spin precession modes and multi‐level resistance. Conversely, the hexagonal nanosheets display slip bands with sAPBs associated with pinning effects, resulting in magnetic‐field‐driven spin texture reversal reminiscent of "0" and "1" switching signals. In support of the micromagnetic simulation, direct explanation is offer to the variation in multi‐level resistance under a microwave field, which is ascribed to the multi‐spin texture magnetization structure and the randomly distributed APBs within the material. These novel 2D magnetite nanosheets with unique spin textures and spin dynamics provide an exciting platform for constructing real multi‐level storage devices catering to emerging information storage and neuromorphic computing requirements. [ABSTRACT FROM AUTHOR]

Conjugated coordination polymers (c‐CPs) are unique organic–inorganic hybrid semiconductors with intrinsically high electrical conductivity and excellent charge carrier mobility. However, it remains a challenge in tailoring electronic structures, due to the lack of clear guidelines. Here, we develop a strategy wherein controlling the redox state of hydroquinone/benzoquinone (HQ/BQ) ligands allows for the modulation of the electronic structure of c‐CPs while maintaining the structural topology. The redox‐state control is achieved by reacting the ligand TTHQ (TTHQ=1,2,4,5‐tetrathiolhydroquinone) with silver acetate and silver nitrate, yielding Ag4TTHQ and Ag4TTBQ (TTBQ=1,2,4,5‐tetrathiolbenzoquinone), respectively. In spite of sharing the same topology consisting of a two‐dimensional Ag−S network and HQ/BQ layer, they exhibit different band gaps (1.5 eV for Ag4TTHQ and 0.5 eV for Ag4TTBQ) and conductivities (0.4 S/cm for Ag4TTHQ and 10 S/cm for Ag4TTBQ). DFT calculations reveal that these differences arise from the ligand oxidation state inhibiting energy band formation near the Fermi level in Ag4TTHQ. Consequently, Ag4TTHQ displays a high Seebeck coefficient of 330 μV/K and a power factor of 10 μW/m ⋅ K2, surpassing Ag4TTBQ and the other reported silver‐based c‐CPs. Furthermore, terahertz spectroscopy demonstrates high charge mobilities exceeding 130 cm2/V ⋅ s in both Ag4TTHQ and Ag4TTBQ. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Electrochemical proton storage plays an essential role in designing next‐generation high‐rate energy storage devices, e.g., aqueous batteries. Two‐dimensional conjugated covalent organic frameworks (2D c‐COFs) are promising electrode materials, but their competitive proton and metal‐ion insertion mechanisms remain elusive, and proton storage in COFs is rarely explored. Here, we report a perinone‐based poly(benzimidazobenzophenanthroline) (BBL)‐ladder‐type 2D c‐COF for fast proton storage in both a mild aqueous Zn‐ion electrolyte and strong acid. We unveil that the discharged C−O− groups exhibit largely reduced basicity due to the considerable π‐delocalization in perinone, thus affording the 2D c‐COF a unique affinity for protons with fast kinetics. As a consequence, the 2D c‐COF electrode presents an outstanding rate capability of up to 200 A g−1 (over 2500 C), surpassing the state‐of‐the‐art conjugated polymers, COFs, and metal–organic frameworks. Our work reports the first example of pure proton storage among COFs and highlights the great potential of BBL‐ladder‐type 2D conjugated polymers in future energy devices. [ABSTRACT FROM AUTHOR]

The combination of plasmonic nanoparticles and optical microcavities has attracted broad interest for both fundamental and applied studies. However, the conventional scheme of plasmonic nanoparticles being located at microcavity outer surfaces suffers from serious problems such as significant radiative/scattering losses and chemical/mechanical instabilities. Here, silver nanoparticles (NPs) and dispersed ions embedded in nanomembrane‐formed whispering‐gallery‐mode (WGM) microtube cavities are prepared by ion implantations as compact and stable optoplasmonic microcavities. Upon low ion fluence implantation, dispersed silver ions are generated in the tube cavity wall, leading to a redshift of the WGM resonant cavity modes due to the increased refractive index. The silver ions start to aggregate into plasmonic NPs in the cavity wall when increasing implantation ion fluences. The competition and transition between redshift induced by the refractive index increase and blueshift induced by the formation of plasmonic NPs are investigated. Moreover, quality factor enhancement of the WGM modes is observed owing to the improved light confinement caused by the presence of NPs. This work demonstrates a convenient approach for the fabrication of stable optoplasmonic microcavities and fine tuning of resonant modes, indicating wide applications such as wavelength selective tuning and enhanced light–matter interactions. [ABSTRACT FROM AUTHOR]

Covalent triazine frameworks (CTFs) are among the most valuable frameworks owing to many fantastic properties. However, molten salt‐involved preparation of CTFs at 400–600 °C causes debate on whether CTFs represent organic frameworks or carbon. Herein, new CTFs based on the 1,3‐dicyanoazulene monomer (CTF‐Azs) are synthesized using molten ZnCl2 at 400–600 °C. Chemical structure analysis reveals that the CTF‐Az prepared at low temperature (400 °C) exhibits polymeric features, whereas those prepared at high temperatures (600 °C) exhibit typical carbon features. Even after being treated at even higher temperatures, the CTF‐Azs retain their rich porosity, but the polymeric features vanish. Although structural de‐conformation is a widely accepted outcome in polymer‐to‐carbon rearrangement processes, the study evaluates such processes in the context of CTF systems. A proof‐of‐concept study is performed, observing that the as‐synthesized CTF‐Azs exhibit promising performance as cathodes for Li‐ and K‐ion batteries. Moreover, the as‐prepared NPCs exhibit excellent catalytic oxygen reduction reaction (ORR) performance; hence, they can be used as air cathodes in Zn‐air batteries. This study not only provides new building blocks for novel CTFs with controllable polymer/carbon features but also offers insights into the formation and structure transformation history of CTFs during thermal treatment. [ABSTRACT FROM AUTHOR]

Sn‐Beta zeolites were successfully synthesized through a quasi‐solid‐phase method by grinding the raw materials and then crystallizing in solid state. The method employed small amount of tetraethyl ammonium hydroxide (TEAOH) and no additional solvent, except for the water contained in template solution. The synthesis conditions including amount of TEAOH and water, and crystallization time were explored. Under optimized conditions, the obtained sample showed high crystallinity and capped square bipyramidal crystals. The diffuse reflectance ultraviolet‐visible spectra and Fourier transform infrared spectra of CD3CN and pyridine adsorption were used to characterize the state of Sn and acidity in Sn‐Beta sample. Sn4+ ions were introduced into the framework which generated strong Lewis acid sites. The sample synthesized by quasi‐solid‐phase method gave 38.5 % methyl lactate (MLA) yield for the conversion of glucose to MLA, which is comparable to that of Sn‐Beta prepared with conventional hydrothermal method (39.4 %). [ABSTRACT FROM AUTHOR]

Complex oxides provide rich physics related to ionic defects. For the proper tuning of functionalities in oxide heterostructures, it is highly desired to develop fast, effective, and low‐temperature routes for the dynamic modification of defect concentration and distribution. Herein, the use of helium implantation to efficiently control the vacancy profiles in epitaxial La0.7Sr0.3MnO3−δ thin films is reported. The viability of this approach is supported by lattice expansion in the out‐of‐plane lattice direction and dramatic change in physical properties, i.e., a transition from ferromagnetic metallic to antiferromagnetic insulating. In particular, a significant increase of resistivity up to four orders of magnitude is evidenced at room temperature, upon implantation of highly energetic He ions. The result offers an attractive means for tuning the emergent physical properties of oxide thin films via strong coupling between strain, defects, and valence. [ABSTRACT FROM AUTHOR]

Trions, quasi‐particles consisting of two electrons combined with one hole or of two holes with one electron, have recently been observed in transition metal dichalcogenides (TMDCs) and drawn increasing attention due to potential applications of these materials in light‐emitting diodes, valleytronic devices as well as for being a testbed for understanding many‐body phenomena. Therefore, it is important to enhance the trion emission and its stability. In this study, a MoSe2/FePS3 van der Waals heterostructure (vdWH) with type‐I band alignment is constructed, which allows for carriers injection from FePS3 to MoSe2. At low temperatures, the neutral exciton (X0) emission in this vdWH is almost completely suppressed. The ITrion/Ix0 intensity ratio increases from 0.44 in a single MoSe2 monolayer to 20 in this heterostructure with the trion charging state changing from negative in the monolayer to positive in the heterostructure. The optical pumping with circularly polarized light shows a 14% polarization for the trion emission in MoSe2/FePS3. Moreover, forming such type‐I vdWH also gives rise to a 20‐fold enhancement of the room temperature photoluminescence from monolayer MoSe2. These results demonstrate a novel approach to convert excitons to trions in monolayer 2D TMDCs via interlayer doping effect using type‐I band alignment in vdWH. [ABSTRACT FROM AUTHOR]

B20‐type transition‐metal silicides or germanides are noncentrosymmetric materials hosting magnetic skyrmions, which are promising information carriers in spintronic devices. The prerequisite is to prepare thin films on technology‐relevant substrates with magnetic skyrmions stabilized at a broad temperature and magnetic‐field working window. A canonical example is the B20‐MnSi film grown on Si substrates. However, the as‐yet unavoidable contamination with MnSi1.7 occurs due to the lower nucleation temperature of this phase. In this work, a simple and efficient method to overcome this problem and prepare single‐phase MnSi films on Si substrates is reported. It is based on the millisecond reaction between metallic Mn and Si using flash‐lamp annealing (FLA). By controlling the FLA energy density, single‐phase MnSi or MnSi1.7 or their mixture can be grown at will. Compared with bulk MnSi, the prepared MnSi films show an increased Curie temperature of up to 41 K. In particular, the magnetic skyrmions are stable over a much wider temperature and magnetic‐field range than reported previously. The results constitute a novel phase selection approach for alloys and can help to enhance specific functional properties, such as the stability of magnetic skyrmions. [ABSTRACT FROM AUTHOR]

Si‐based photodetectors satisfy the criteria of being low‐cost and environmentally friendly, and can enable the development of on‐chip complementary metal‐oxide‐semiconductor (CMOS)‐compatible photonic systems. However, extending their room‐temperature photoresponse into the mid‐wavelength infrared (MWIR) regime remains challenging due to the intrinsic bandgap of Si. Here, we report on a comprehensive study of a room‐temperature MWIR photodetector based on Si hyperdoped with Te. The demonstrated MWIR p‐n photodiode exhibits a spectral photoresponse up to 5 µm and a slightly lower detector performance than the commercial devices in the wavelength range of 1.0–1.9 µm. The correlation between the background noise and the sensitivity of the Te‐hyperdoped Si photodiode, where the maximum room‐temperature specific detectivity is found to be 3.2 × 1012 cmHz1/2 W−1 and 9.2 × 108 cmHz1/2 W−1 at 1 µm and 1.55 µm, respectively, is also investigated. This work contributes to pave the way towards establishing a Si‐based broadband infrared photonic system operating at room temperature. [ABSTRACT FROM AUTHOR]

The photonic bandgap and localization in photonic crystals can be effectively modulated by energetic ion beams owing to the induced modification of the thickness and refractive indices of the materials. In this work, the modulation of photonic bandgap and defect modes in 1D all‐dielectric photonic crystals is investigated theoretically and experimentally by using carbon (C5+) ion irradiation. It is found that the photonic bandgap and defect mode have a remarkable hypsochromic shift under the C5+ ion irradiation. The degree of the blueshift mainly depends on the reduction of the material thickness that is nearly proportional to the fluences of C5+ ions. The blueshift of the band edges and defect modes shows a step‐like behavior from transparency to opacification (near‐zero transmittance or high reflectance) or a converse trend. The work paves a new way to tailor the photonic crystals toward the development of novel devices with tunable specific wavelengths and wavebands. [ABSTRACT FROM AUTHOR]

Herein, the properties of ZnO:N/n‐SiC heterojunctions (HJs) and light‐emitting diodes based on them are studied. The HJs are grown by molecular beam epitaxy. Active nitrogen generated by a radio frequency plasma source is used for p‐type doping. The location of the space charge area on the ZnO:N/n‐SiC interface is revealed by electron‐beam‐induced current (EBIC) scans. The diffusion lengths of holes and electrons are calculated. This article presents the characterization of ZnO:N/n‐SiC HJs and reveals the presence of tunneling‐related current transport in them as well as the contribution of exponentially distributed traps at large voltage bias. Electroluminescence (EL) is measured at ambient pressure by a standard EL system and also at 77 K in vacuum by a system utilizing EBIC in a scanning electron microscope. Analysis of the light output power at higher current level indicates the limited effect of nonradiative defects in this structure. EL results are compared with cathodoluminescence spectra. Color temperature for HJs based on the EL spectra is also calculated. [ABSTRACT FROM AUTHOR]

2D conjugated metal‐organic frameworks (2D c‐MOFs) are emerging as a novel class of conductive redox‐active materials for electrochemical energy storage. However, developing 2D c‐MOFs as flexible thin‐film electrodes have been largely limited, due to the lack of capability of solution‐processing and integration into nanodevices arising from the rigid powder samples by solvothermal synthesis. Here, the synthesis of phthalocyanine‐based 2D c‐MOF (Ni2[CuPc(NH)8]) nanosheets through ball milling mechanical exfoliation method are reported. The nanosheets feature with average lateral size of ≈160 nm and mean thickness of ≈7 nm (≈10 layers), and exhibit high crystallinity and chemical stability as well as a p‐type semiconducting behavior with mobility of ≈1.5 cm2 V−1 s−1 at room temperature. Benefiting from the ultrathin feature, the nanosheets allow high utilization of active sites and facile solution‐processability. Thus, micro‐supercapacitor (MSC) devices are fabricated mixing Ni2[CuPc(NH)8] nanosheets with exfoliated graphene, which display outstanding cycling stability and a high areal capacitance up to 18.9 mF cm−2; the performance surpasses most of the reported conducting polymers‐based and 2D materials‐based MSCs. [ABSTRACT FROM AUTHOR]

Nanographenes (NGs) with tunable electronic and magnetic properties have attracted enormous attention in the realm of carbon‐based nanoelectronics. In particular, NGs with biradical character at the ground state are promising building units for molecular spintronics. However, most of the biradicaloids are susceptible to oxidation under ambient conditions and photolytic degradation, which hamper their further applications. Herein, we demonstrated the feasibility of tuning the magnetic properties of zigzag‐edged NGs in order to enhance their stability via the controlled Diels–Alder reactions of peri‐tetracene (4‐PA). The unstable 4‐PA (y0=0.72; half‐life, t1/2=3 h) was transformed into the unprecedented benzo‐peri‐tetracenes (BPTs) by a one‐side Diels–Alder reaction, which featured a biradical character at the ground state (y0=0.60) and exhibited remarkable stability under ambient conditions for several months. In addition, the fully zigzag‐edged circumanthracenes (CAs) were achieved by two‐fold or stepwise Diels–Alder reactions of 4‐PA, in which the magnetic properties could be controlled by employing the corresponding dienophiles. Our work reported herein opens avenues for the synthesis of novel zigzag‐edged NGs with tailor‐made magnetic properties. [ABSTRACT FROM AUTHOR]

The topological Hall effect (THE) has been discovered in ultrathin SrRuO3 (SRO) films, where the interface between the SRO layer and another oxide layer breaks the inversion symmetry resulting in the appearance of THE. Thus, THE only occurs in ultrathin SRO films of several unit cells. In addition to employing a heterostructure, the inversion symmetry can be broken intrinsically in bulk SRO by introducing defects. In this study, THE is observed in 60‐nm‐thick SRO films, in which defects and lattice distortions are introduced by helium ion irradiation. The irradiated SRO films exhibit a pronounced THE in a wide temperature range from 5 to 80 K. These observations can be attributed to the emergence of Dzyaloshinskii–Moriya interaction as a result of artificial inversion symmetry breaking associated with the lattice defect engineering. The creation and control of the THE in oxide single layers can be realized by ex situ film processing. Therefore, this work provides new insights into the THE and illustrates a promising strategy to design novel spintronic devices. [ABSTRACT FROM AUTHOR]

Abstract: Plasmonic Au nanoparticles embedded in LiNbO3 crystals as efficient saturable absorbers to realize 74.1 ps mode‐locked laser pulse generation at 1 µm are reported. The system is fabricated by Au ion implantation and subsequent annealing, a well‐developed chip technology. The strong optical absorption band peaking at 640 nm is observed due to the localized surface plasmon resonance. Z‐scan investigation shows that the LiNbO3 crystals with embedded Au nanoparticles possess ultrafast saturable absorption properties at near‐infrared 1 µm wavelength. With this feature the Au nanoparticles embedded LiNbO3 wafer is applied as saturable absorber into a laser‐written Nd:YVO4 waveguide platform. Stable laser pulses at 1064 nm based on an efficient passive Q‐switched mode‐locking process, reaching a fundamental repetition rate of 6.4 GHz and a pulse duration of 74.1 ps, are obtained. Since LiNbO3 has broadband applications in various optical systems, this work opens the way to develop intriguing devices in LiNbO3‐based photonic circuits by using embedded metallic nanoparticles. [ABSTRACT FROM AUTHOR]

Abstract: Hyperdoping consists of the intentional introduction of deep‐level dopants into a semiconductor in excess of equilibrium concentrations. This causes a broadening of dopant energy levels into an intermediate band between the valence and the conduction bands. Recently, bulk Si hyperdoped with chalcogens or transition metals is demonstrated to be an appropriate intermediate‐band material for Si‐based short‐wavelength infrared photodetectors. Intermediate‐band nanowires can potentially be used instead of bulk materials to overcome the Shockley–Queisser limit and to improve efficiency in solar cells, but fundamental scientific questions in hyperdoping Si nanowires require experimental verification. The development of a method for obtaining controlled hyperdoping levels at the nanoscale concomitant with the electrical activation of dopants is, therefore, vital to understanding these issues. Here, this paper shows a complementary metal‐oxide‐semiconductor (CMOS)‐compatible technique based on nonequilibrium processing for the controlled doping of Si at the nanoscale with dopant concentrations several orders of magnitude greater than the equilibrium solid solubility. Through the nanoscale spatially controlled implantation of dopants, and a bottom‐up template‐assisted solid phase recrystallization of the nanowires with the use of millisecond‐flash lamp annealing, Se‐hyperdoped Si/SiO2 core/shell nanowires are formed that have a room‐temperature sub‐bandgap optoelectronic photoresponse when configured as a photoconductor device. [ABSTRACT FROM AUTHOR]

Lithium silicon phosphorus oxynitride (LiSiPON) thin films with different compositions have been prepared by RF magnetron sputtering in N2 by using three targets xLi2SiO3 · (1 − x) Li3PO4 with x = 0.1, 0.3, and 0.5. Compared with LiPON, the electrical properties of LiSiPON have been improved by introducing silicon. LiSiPON films deposited from the target 0.5Li2SiO3 · 0.5Li3PO4 yield the highest ionic conductivity of up to 9.7 × 10−6 S cm−1 with an activation energy of only 0.41 eV. The main mechanism for increasing ionic conductivity is the enhancement of carrier mobility. By DC polarization measurements the electronic partial conductivity was found at least seven orders of magnitude smaller than the ionic conductivity. Linear voltammetry results showed that the LiSiPON films are electrochemically stable in contact with stainless steel in the voltage range of 0-6 V. The substitution of silicon for phosphorus in the film evidenced from X-ray photoelectron spectroscopy analysis indicated silicon in the film will create more abundant cross-linking structures Si-O-P and (P, Si)-N < (P, Si), hence created more Li+ conducting paths which favored the higher mobility of lithium ions and larger ionic conductivity. The optical bandgap was found to decrease with increasing silicon content. We demonstrate that the prepared LiSiPON films with their larger ionic conductivity and low electronic conductivity may serve as an alternative to LiPON for applications in high energy density and high voltage lithium batteries. [ABSTRACT FROM AUTHOR]

The transport properties of metal-insulator-metal (MIM) capacitor-like structures have been demonstrated to be sensitive to the metal-insulator interface. BiFeO3 thin films have been grown on Pt/Ti/SiO2/Si substrates with pulsed laser deposition and RF sputtered Au has been used for the top electrode. As quantified by validated memristance measurements, Ar+ irradiation before deposition of the Au top electrode improved the retention of the BiFeO3 -based MIM structures. In principle it is possible to realize multilevel resistive switching with a very large number of intermediate low resistance states in BiFeO3-based MIM structures which is mainly limited by the writing bias. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

P‐type hyperdoped germanium (Ge) has attracted significant attention for the development of superconducting semiconductors. However, the limited solid solubility of acceptors, especially boron (B), in Ge makes hyperdoping challenging. Herein, a systematic study on the electrical properties of boron‐implanted germanium is presented with an atomic concentration beyond 10 at%. The B‐implanted Ge was annealed by millisecond flash lamp annealing (ms‐FLA) with different parameters. The results indicate that millisecond solid phase epitaxy ensures the electrical activation of B much above the solubility limit with hole concentration as high as 2 × 1021 cm−3 and low‐temperature sheet resistance of 13 Ω sq−1 which is promising for superconductivity. It is also shown that millisecond annealing effectively suppresses the B diffusion and provides much higher activation efficiency of acceptors compared to conventional annealing methods. [ABSTRACT FROM AUTHOR]

Nanostructured silicon can reduce reflectance loss in optoelectronic applications, but intrinsic silicon cannot absorb photons with energy below its 1.1 eV bandgap. However, incorporating a high concentration of dopants, i.e., hyperdoping, to nanostructured silicon is expected to bring broadband absorption ranging from UV to short‐wavelength IR (SWIR, <2500 nm). In this work, we prepare nanostructured silicon using cryogenic plasma etching, which is then hyperdoped with selenium (Se) through ion implantation. Besides sub‐bandgap absorption, ion implantation forms crystal damage, which can be recovered through flash lamp annealing. We study crystal damage and broadband (250–2500 nm) absorption from planar and nanostructured surfaces. We first show that nanostructures survive ion implantation hyperdoping and flash lamp annealing under optimized conditions. Secondly, we demonstrate that nanostructured silicon has a 15% higher sub‐bandgap absorption (1100–2500 nm) compared to its non‐hyperdoped nanostructure counterpart while maintaining 97% above‐bandgap absorption (250–1100 nm). Lastly, we simulate the sub‐bandgap absorption of hyperdoped Si nanostructures in a 2D model using the finite element method. Simulation results show that the sub‐bandgap absorption is mainly limited by the thickness of the hyperdoped layer rather than the height of nanostructures. [ABSTRACT FROM AUTHOR]

With the demand of aggressive scaling in nanoelectronics, further progress can be realized by integration of high mobility semiconductors, such as III–V compound semiconductors, with complementary metal‐oxide‐semiconductor (CMOS) technology. In this study, the formation of shallow n–p and p–n junctions in GaAs utilizing ion implantation of S and Zn, respectively, followed by millisecond‐range flash lamp annealing (FLA) is presented. The distribution of implanted elements obtained by secondary ion mass spectrometry (SIMS) shows that the FLA process can effectively suppress the diffusion of dopants. Simultaneously, the ms‐range annealing is sufficient to recrystallize the implanted layer and to activate the dopants. Formation of p–n and n–p junctions is confirmed by current–voltage characteristics. The ratio of reverse to forward current can reach up to 1.7 × 107 in the n‐GaAs:Zn case. [ABSTRACT FROM AUTHOR]

Review: 183 refs. [ABSTRACT FROM AUTHOR]

Review: 56 refs. [ABSTRACT FROM AUTHOR]

The title compound is obtained by arc melting of stoichiometric amounts of the elements followed by annealing at 900 °C for six days. [ABSTRACT FROM AUTHOR]