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High-quality III–V quantum structures, advanced epitaxial technologies, and characterization methods are essential to drive the development of infrared optoelectronic materials and devices. As an important component of type II superlattices, InAs/InxGa1−xAsySb1−y would play an important role in the field of high-performance infrared detectors due to their excellent luminescence efficiency and high crystal quality. However, their interfacial characteristics and the associated minority carrier lifetime are still difficult to identify. In this paper, an atomic imaging technique was used to identify the arrangement and distribution of elements of the InAs/In0.5Ga0.5As0.5Sb0.5 superlattice. Our results confirm the epitaxy mechanism that the quaternary alloy consists of two kinds of ternary alloy in one monolayer. Moreover, by separating the cation and anion columns in the elementally resolved atomic images of the InAs/In0.5Ga0.5As0.5Sb0.5 superlattice, we demonstrate that the interfacial atomic intermixing is less than one molecular layer thickness. Therefore, benefiting from excellent interface quality, InAs/In0.5Ga0.5As0.5Sb0.5 superlattice exhibited high radiation recombination efficiency in the long-wave infrared band (∼8.5 μm), and longer minority carrier lifetime (∼810 ns at 90 K). [ABSTRACT FROM AUTHOR]

Identifying interfacial properties and discussing optical properties of antimony‐based type II superlattices are the key factors for developing high performance of infrared optoelectronic devices. Herein, the multi‐epitaxy‐layered structure of a mid‐wavelength‐responsive infrared detector with an InAs/InAsSb superlattice as an active area layer is grown and investigated. High‐resolution X‐ray diffraction, high‐resolution transmission electron microscopy, and the geometric phase analysis indicate epitaxial layers of high crystalline quality and small lattice mismatches. The electric field results obtained by differential phase contrast scanning transmission electron microscopy further confirm the sharp interface states and good periodic structure of the as‐grown samples. The photoluminescence spectrum shows that the photoluminescence signal center is 5.4 μm at 75 K, even at 320 K, the sample still maintains a photoluminescence signal of 6.2 μm. [ABSTRACT FROM AUTHOR]

An effect of rapid thermal annealing (RTA) on emission properties of InGaAsSb/AlGaAsSb multiple quantum wells (MQWs) grown by molecular‐beam epitaxy is systematically investigated by photoluminescence (PL) spectra. The emission from free‐exciton and localized carriers is confirmed in as‐grown InGaAsSb/AlGaAsSb MQWs using temperature and excitation power‐dependent PL spectra. The results of RTA for different times at a fixed temperature of 350 °C are analyzed. The PL intensity of InGaAsSb/AlGaAsSb MQWs is increased after an RTA process, and the peak position is slightly blueshifted at 300 K. Low‐temperature PL spectra show improved emission of free‐exciton and deteriorated localized carriers recombination at an annealing time of 60 s. Double crystal X‐ray diffraction (DCXRD) measurements are also carried out to study the crystalline quality before and after annealing. These results indicate that a suitable RTA treatment is effective in reducing the densities of nonradiative recombination centers, which implies an improved optical property and crystalline quality of quantum well structures. This study provides valuable understanding of recombination processes and improvement of optical properties by RTA treatment in InGaAsSb/AlGaAsSb MQWs. [ABSTRACT FROM AUTHOR]

Surface passivation is an effective way to eliminate the surface states and to improve the optical properties of GaAs. Moreover, carriers restriction of wide bandgap materials also is a path to enhance photoluminescence. In this paper, Be-doped GaAs epilayer was growth on GaAs substrate by molecular beam epitaxy. The MgO films were deposited by atom layer deposition. It was used as not only passivation layer to eliminate surface states, but also barrier layer to restrict carriers. The carriers restriction was confirmed by photoluminescence and current-voltage characteristics of metal-insulator-semiconductor structure. As the result, the photoluminescence intensity of Be-doped GaAs with 5 nm MgO was 2.5 times higher than the bare Be-doped GaAs. [ABSTRACT FROM AUTHOR]

The optical properties of GaSb strongly depend on the defect types and concentration. Doping is an effective method to improve the optical properties by changing the native defect types and concentration. In this paper, the native defects related emissions were suppressed through defects compensation via Be-doping. The un-doped and Be-doped GaSb were fabricated by molecular beam epitaxy. Temperature- and excitation power-dependent photoluminescence were applied to investigate optical properties of GaSb epilayer. The Ga vacancy related emission disappeared after Be doping. This phenomenon can be explained by the defect compensation between Be atoms and Ga vacancy, which greatly reduced the concentration of native defects. To certify this theory, Te-doped GaSb was prepared. For Te-doped GaSb, Te Sb recombined with native defects and formed new complex defects, which enhanced the defects related emission peak. The investigation of optical properties of doped GaSb epilayer was great significant for practical application of GaSb-based devices. [ABSTRACT FROM AUTHOR]

ZnO nanowires play a very important role in optoelectronic devices due to the wide bandgap and high exciton binding energy. However, for one-dimensional nanowire, due to the large surface to volume ratio, surface traps and surface adsorbed species acts as an alternate pathway for the de-excitation of carriers. Ar plasma treatment is a useful method to enhance the optical property of ZnO nanowires. It is necessary to study the optical properties of ZnO nanowires treated by plasma with different energies. Here, we used laser spectroscopy to investigate the plasma treatments with various energies on ZnO nanowires. Significantly improved emission has been observed for low and moderate Ar plasma treatments, which can be ascribed to the surface cleaning effects and increased neutral donor-bound excitons. It is worth mentioning that about 60-folds enhancements of the emission at room temperature can be achieved under 200 W Ar plasma treatment. When the plasma energy exceeds the threshold, high-ion beam energy will cause irreparable damage to the ZnO nanowires. Thanks to the enhanced optical performance, random lasing is observed under optical pumping at room temperature. And the stability has been improved dramatically. By using this simple method, the optical property and stability of ZnO nanowires can be effectively enhanced. These results will play an important role in the development of low dimensional ZnO-based optoelectronic devices. [ABSTRACT FROM AUTHOR]

GaAs nanowires (NWs) play important roles in the field of low-dimensional infrared photodetector and laser. In this work, the GaAs NWs are directly grown on Al 2 O 3 , Si and SiO 2 substrates by metal organic chemical vapor deposition. The structural, optical and electrical properties of these NWs are further studied to reveal the effect of substrates. Using transmission electron microscopy characterization, the wurtzite/zinc-blend (WZ/ZB) mixed-phase structure and plenty of defects are directly observed in the GaAs NWs grown on Si and SiO 2 substrates. But the GaAs NWs grown on Al 2 O 3 substrates are high-quality, uniform and single-phase. The peak shapes of the photoluminescence (PL) spectra of the three samples are quite different, which is essentially attributed to the structural difference. Temperature- and power-dependent PL spectra are performed to analyze the origin of peaks. The luminescence of GaAs NWs on Al 2 O 3 substrate originates from exciton related recombination, while that of the GaAs NWs on Si and SiO 2 substrates come from free exciton emission, the defect-related emission and the radiative recombination at the WZ/ZB mixed-phase interface. The electron mobility of GaAs NWs on Al 2 O 3 substrate is higher than that on Si and SiO 2 substrates, which is due to the small carriers scattering of pure phase nanowires. This work has a great influence on the fabrication of GaAs NWs and their application in optoelectronic devices. [ABSTRACT FROM AUTHOR]

Construction of heterostructures can circumvent the shortcomings of 2D material components and has potential for applications in optoelectronic devices. Therefore, further development and construction of novel 2D materials is highly important. In this paper, a seamless lateral heterostructure (LHS) based on arsenene (As) and antimonene (Sb) along armchair (AC) and zigzag (ZZ) interfaces is predicted, and the band structures and optical absorption properties with the different interfaces are calculated from first principles. An indirect to direct band structure transition can be observed when the LHS interface changes from AC to ZZ. Additionally, the band gaps of the different (AC and ZZ) heterostructure types exhibit strong atomic number dependences, and can be narrowed from 1.1 to 0.45 eV and from 0.57 to 0.50 eV, respectively. The partial density of states (PDOS) and the conduction band minimum-valence band maximum (CBM-VBM) characteristics clarify the contributions from the different orbits to the band structures around the Fermi level. It should be noted that As/Sb lateral heterostructures have unique optical absorption characteristics in the mid-infrared range. Our predictions highlight the potential applications of As and Sb LHSs in electronics and optoelectronics. These results provide another 2D material with potential applications in mid-infrared optoelectronic devices. • Predict a lateral heterostructure made from As and Sb with armchair and zigzag interfaces. • Indirect to direct band structure change occurs with armchair to zigzag variation. • The lateral heterostructure band gaps narrowed to 0.50 eV for zigzag. • Unique optical absorption characteristics are found in the mid-infrared range. [ABSTRACT FROM AUTHOR]

Third-order nonlinear optical and optical limiting properties of MAPbBr 3 /polymethyl methacrylate (PMMA) are adjusted by doping with Zn. X-ray diffraction and photoluminescence are performed to confirm the effective doping of Zn. Typical reverse saturable absorption and self-focusing effects are observed in the undoped MAPbBr 3 /PMMA and Zn-doped MAPbBr 3 /PMMA. After Zn doping, the nonlinear absorption coefficient becomes larger but nonlinear refraction coefficient becomes smaller. This may be related to the decreased defect states after Zn doping. Besides, both values of the optical limiting threshold and the clamping normalized transmittance for the Zn-doped MAPbBr 3 /PMMA are obviously smaller than those of the undoped sample, indicating that its optical limiting property enhances. The reverse saturable absorption properties are caused by one photon absorption-induced excited-state absorption processes, which have been explained by using three-energy-level diagrams. The nonlinear optical and optical limiting properties of the Zn-doped MAPbBr 3 /PMMA make it show great potentials for application in optical limiter. • The defect concentration of MAPbBr 3 is reduced after Zn doping. • The undoped MAPbBr 3 /PMMA and Zn-doped MAPbBr 3 /PMMA both exhibit reverse saturable absorption properties and self-focusing effects. • The nonlinear optical and optical limiting properties of MAPbBr 3 are enhanced after Zn doping. • The Zn-doped MAPbBr 3 /PMMA shows great potentials for application in optical limiter. [ABSTRACT FROM AUTHOR]