We report on the investigation of the long term stability study of InAs<sub>1-x</sub>Sb<sub>x </sub>(x=0.09) high operation temperature (HOT) photodiode grown on GaAs substrate. The electrochemical passivation technique was proposed to modify the mesa sidewalls properties and obtain anodic sulphur coating covered by SU-8 negative photoresist. The dark current densities of sulphur anodic film, SU-8 photoresist and unpassivated devices was compared. Obtained results indicates that the surface leakage current was not fully supressed by unipolar electron barrier. The most stable behaviour after an exposure of 6 months to atmosphere and annealing at 373 K for 72 h was observed for sulphur anodic passivation. This technique turned to be effective also in reduction of oxygen (O) 2s peak in X-ray photoelectron spectroscopy (XPS) in comparison with only etched sample.
The highly Be-doped InAs layer has been grown on semi-insulating GaAs (100) substrate by Molecular Beam Epitaxy. Very good quality of the layer has been attested by high resolution scanning electron microscope (HR-SEM), X-ray diffraction (XRD) and the Raman spectra. The parallel and perpendicular residual strain are determined to be – 1.17 × 10<sup>-3</sup> , and 1.12 × 10<sup>-3</sup> , respectively. Moreover, the absorbance (ABS) and photoluminescence (PL) spectra were collected in order to estimate the bandgap narrowing. The 10 meV bandgap shrinking for 1.7×10<sup>18</sup> cm<sup>-3</sup> acceptor concentration suggests necessity of reexamining the Jain et al model [Jain, S. C., et al. - JAP 68(7): 3747-3749] in the context of actual values of InAs valence-bands effective-masses.
In this work we compare two InAs/GaSb superlattice samples grown in MBE VIGO/MUT laboratory on 2 inch (001) GaAs substrate, using MBE technique. Both samples have the same architecture, however their growth processes were conducted at different temperatures. For sample A the growth temperature was equal 668 K (395°C), for sample B 588 K (315°C). Photoluminescence measurements were performed at 30 K. For sample A there is no photoluminescence signal, while spectrum for sample B consists of two peaks: bandgap peak at 0.5 eV and deep state peak at 0.25 eV. X-ray diffraction (XRD) measurements indicate that sample A has better crystallographic quality than sample B. Raman spectra consists of low energy peaks (20-100 cm<sup>-1</sup>) which confirm the existence of superlattice for both samples . Additionally, for sample A there are peaks related to Sb precipitates. It suggests that except the InAs/GaSb superlattice there is an additional Sb layer which may disturb band structure of superlattice and cause the disappearance of photoluminescence for sample A.
In this work we compare two superlattices: InAs/GaSb (sample A) and InAs/InAsSb (sample B). Both samples were grown in MBE VIGO/ MUT laboratory on 2 inch (001) GaAs substrate using MBE technique. We characterized quality and thickness of the samples using three methods: photoluminescence, X-ray diffraction (XRD) and Raman scattering. Period of superlattice layers was obtained using Raman scattering and XRD measurements. For sample A it was equal 5.3 nm and 4.76 nm for InAs and GaSb layers respectively, for sample B 8.3 nm and 9.4 nm. Photoluminescence spectrum for sample A exhibits two peaks: band gap peak at 0.5 eV and deep state peak at 0.25 eV. Spectrum for sample B consists of one band gap peak at 0.17 eV.