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Electron irradiation causes atomic displacement damage and produces point defects in semiconductor materials. The formation and variation of defects determine the optical properties of semiconductors during the irradiation process. In this paper, Te-doped GaSb was irradiated by 1 MeV electrons, with fluence of 1 × 1015 electrons cm−2, and its optical properties investigated by temperature-dependent photoluminescence (PL) before and after irradiation. After irradiation, the peak position had a blue-shift and intensity was significantly enhanced. The carrier concentration increased from 4.14 × 1017 to 7.82 × 1017 cm−3 but mobility decreased from 2690 to 1780 cm2 V−1 s−1. These phenomena could be explained by the complex mechanism of defect decomposition, that is, the V Ga Ga Sb Te Sb defect decomposed into two independent V Ga Ga Sb and Te Sb defects. To verify this mechanism, undoped GaSb was irradiated under the same conditions and PL results indicated that electron irradiation had little effect on optical properties of undoped GaSb. • Mechanism proposed for electron irradiation and complex defects in Te-doped GaSb. • V Ga Ga Sb Te Sb defect decomposed to V Ga Ga Sb and Te Sb defects after irradiation. • The electron irradiation reduced the photoluminescence properties of Te-doped GaSb. [ABSTRACT FROM AUTHOR]

X-ray photoelectron spectroscopy was used to measure the valence-band offset ( ΔE V ) of MgO/InP heterostructure. Two sets of core level pairs in the MgO/InP system were used to demonstrate the accuracy of the calculation, the ΔE V value was the same (5.33 ± 0.15 eV) when using the In 3d 3/2 , Mg 2p pair and In 3d 5/2 , Mg 2p pair, indicating our calculations are accuracy and reasonable. Taking the band gaps of 7.83 eV for MgO and 1.34 eV for InP into consideration, a type-I band alignment of MgO/InP heterostructure was obtained with conduction band offset (CBO) of 1.16 ± 0.15 eV for two sets of core level pairs, indicating a nested interface band alignment heterostructure was prepared. The accurate determination of the band alignment of MgO/InP has a significant impact on the performance of InP-based devices. [ABSTRACT FROM AUTHOR]

The two-dimensional non-layered sheets (2DNLSs) have been paid much attention because of their large surface-to-volume ratio and special photoelectric properties. However, the large surface states density introduced by surface oxides greatly hinder the performance of 2DNLSs optoelectronics devices. In this paper, the sulfur passivation and plasma treatment are performed to remove the surface states of GaAs 2DNLSs. Before surface treatment, the responsivity and detectivity of GaAs 2DNLSs photodetector are 0.1 AW-1 and 9.6 × 1010 Jones at 8 V, respectively. After sulfur passivation, the responsivity is significantly enhanced about 14 folds and the dark current is remarkably reduced. We confirm that the origin of the improvement of responsivity and the reduction of dark current is the decrease in the surface states density. Furthermore, the performances of photodetector with plasma treatment are almost same with those of sulfur passivated photodetector. This work provides efficient methods to improve the performance of materials and devices based on 2DNLSs. • GaAs 2DNLSs was prepared by chemical stripping. • Plasma and sulfur passivation are used to eliminate the surface state of the material. • After the surface state is reduced, the responsivity of GaAs 2DNLS photodetector is effectively improved. [ABSTRACT FROM AUTHOR]

AlGaAs materials are used in a variety of cutting-edge devices and the band gap states after the surface oxidization is found with Fermi level pinning. With first-principle calculations, we explore the formation of gap states during the initial stage of native-oxide growth on Al 0.5 Ga 0.5 As (001) surface. The results indicate that oxygen adsorption at the bridge sites of Al (Ga)-As satisfies the bond saturation and doesn't lead to any effect on the surface gap states. The breaking of As-As dimer results in the defect states in band gap with Fermi level pining due to the replacement of oxygen. In the oxidization process, it is found that the As-As dimer is very easy to be broken. In addition, the defect states in band gap maybe disappear after the full oxidization of surface with the elimination of unsaturated As on surface. With these gap states, some absorption peaks are found to appear in the range of 0–1 eV in the absorption spectra. [ABSTRACT FROM AUTHOR]

Recently, Al 2 O 3 has been demonstrated to be an effective material type for perovskite photoelectric device performance improvement. It is therefore essential to investigate the interfacial electronic characteristics and the energy-level diagrams of perovskite/Al 2 O 3 heterojunctions in depth. In this research, we fabricated an MAPbBr 3 microcrystal/Al 2 O 3 film heterojunction and determined the band offset by performing X-ray photoelectron spectroscopy measurements. The resulting valence band offset of Δ E v = 0.87 ± 0.01 eV and the conduction band offset of Δ E c = 3.03 ± 0.01 eV indicated occurrence of a type-I band alignment at the MAPbBr 3 /Al 2 O 3 heterointerface. The carrier confinement effect was reflected in the photoluminescence spectra obtained for the heterojunction sample. This work will be valuable for optimization of the energy level alignment of perovskite/metallic oxide heterojunctions during the design of photoelectric devices. • MAPbBr 3 /Al 2 O 3 composites were synthesized through ALD at low temperature. • We measured the band offset and band alignment of MAPbBr 3 /Al 2 O 3 composites. • An enhancement in PL intensity can be clearly seen for MAPbBr 3 /Al 2 O 3 composites. [ABSTRACT FROM AUTHOR]

Board spectral photodetectors are required for varied scientific and industrial applications, yet the studies of such devices are limited. In this work a CdSe/ZnS quantum dots (QDs) based photodetector with broad spectral detecting ability was fabricated through a simple approach. Due to the discrete electronic states of QDs, the photodetector was more sensitive to incident wavelengths than incident power densities, and the photocurrent decreased monotonously with increasing incident wavelength, which could also realize the wavelength detection of incident light. This character provides a new way to achieve color or image sensing, and it could also broaden the photodetection and photosensing applications of QDs and semiconductor detectors. [ABSTRACT FROM AUTHOR]

[Display omitted] • The surface structure of oxidized GaSe was revealed directly at the atomic scale. • Generation of Ga 2 Se 3 /GaSe heterostructure through GaSe oxidation was purposed. • The Ga 2 Se 3 /GaSe heterostructure show atomically epitaxy growth relationship. • The optical properties of Ga 2 Se 3 /GaSe heterostructures were preliminary studied. Gallium selenides (GaSe and Ga 2 Se 3) and their heterostructures have been widely concerned owing to their attractive properties and potential applications in the field of photoelectric and photocatalysis. In this work, we develop an unprecedented Ga 2 Se 3 /GaSe self-assembled heterostructure through thermal oxidation of GaSe. The crystal structure and defects of GaSe and Ga 2 Se 3 /GaSe heterostructure have been studied by advanced Cs-STEM imaging. The present bulk GaSe possesses ε -polytype as the dominant phase along with γ -GaSe inclusions and structural defects, i.e., stacking faults, twins, and antisites. The Ga 2 Se 3 layer, generated on the GaSe oxidized surface, exhibits a defective zincblende-like cubic structure where vacancies locally ordered on the {1 1 1} planes, which even results in superstructure domains. Furthermore, atomically van der Waals epitaxy and orientation relationships between Ga 2 Se 3 and GaSe were revealed. Finally, the optical properties of Ga 2 Se 3 /GaSe heterostructures were preliminary studied and future directions for the structural development and property investigation of Ga 2 Se 3 /GaSe heterostructures were also discussed. These findings are insightful for recognizing the microscopic structure of GaSe and Ga 2 Se 3 /GaSe heterostructures and provide a valuable route for the generation of self-assembled heterostructures in other related layered semiconductors. [ABSTRACT FROM AUTHOR]

We realized the control on the crystal structure of GaAs nanowires (NWs) by silicon (Si) doping and V/III ratio. This viewpoint has been clearly evidenced by Raman spectrum combined with high-resolution transmission electron microscopy (HRTEM). Undoped GaAs NWs generally show a mixture of zinc blende (ZB) and wurtzite (WZ) phases; the addition of Si dopant and high V/III ratio are beneficial for the nucleation of ZB structure. Field effect transistor (FET) devices were fabricated to show that Si-doped GaAs NWs exhibit p-type conductivity in the low V/III ratio of 25.8 and n-type conductivity in the high V/III ratio of 51.6. These results provide a clear route for achieving GaAs NWs phase control and different conductivity types, which is an essential step towards the fabrication of nanoscale devices. • Phase control, formation of p-type and n-type GaAs NWs were designed and fabricated by Si doping and V/III ratio using MBE. • The doping-induced phase control from WZ/ZB mixed phase to the pseudo-pure phase ZB structure in the GaAs NWs were clearly revealed. • Si-doped GaAs NWs exhibit p-type and n-type conductivity with different V/III ratios were determined by FET. [ABSTRACT FROM AUTHOR]

GaAsSb based materials have become the promising system for infrared semiconductor lasers and detectors. In this article, the strain, energy band structures and photoluminescence (PL) of GaAs 0.92 Sb 0·08 /Al 0.3 Ga 0.7 As strained quantum wells (QWs) grown with molecular beam epitaxy are systematically analyzed both theoretically and experimentally. The theoretical results are derived by Kane's model and k⋅p method, and the optical properties of a high-quality GaAs 0.92 Sb 0·08 /Al 0.3 Ga 0.7 As strained QWs sample are thoroughly investigated by excitation- and temperature-dependent PL measurements. The theoretical results show the strain has significant influence on the band structure of QWs. In experimental part, it is found that the light-hole exciton emission coexists with the heavy-hole exciton line in the temperature range of 50 K–300 K. However, the emission of localized excitons, which is caused by the nonuniformity of component in the GaAsSb well layer, takes over the light-hole exciton emission at lower temperatures (<50 K). • The band structures of the GaAsSb/AlGaAs QW with and without strain calculated by using Kane's model and k-p method. • The energy deviation between the heavy-hole and light-hole emission peaks is in good agreement with the calculation result. • The emission of localized excitons takes over the light-hole exciton emission at lower temperatures. [ABSTRACT FROM AUTHOR]