Qiwei Wang

Single crystalline InAsxSb1-x grown on (100) InSb substrate by liquid phase epitaxy

Single crystalline InAs0.016Sb0.984 film has been successfully grown on (100) InSb substrate by LPE method. A large supercooling (ΔT = 15 °C) had been used to prevent substrate from dissolving into the epilayer. High resolution X-ray diffraction (HRXRD) measurement was used to characterize the crystal quality of the film. Only (200) and (400) peaks were observed from the XRD spectrum, indicating that the film was single crystalline with (100) orientation. The Fourier transform infrared (FTIR) transmission spectrum of the film at room temperature revealed 7.77 μm cut-off wavelength of the film. The lattice dynamics of the epilayer was studied by Raman scattering, suggests two-mode behavior of the optical phonons.

High quality mid-infrared InAs film grown on (100) GaSb substrate by LPE using a ternary melt

InAs film has been successfully grown on (100) GaSb substrate using a ternary In-As-Sb melt by liquid phase epitaxy (LPE). The high resolution X-ray diffraction (HRXRD) and Rocking curve showed the film was single crystalline InAs with high quality. The Fourier transform infrared (FTIR) transmission spectrum revealed that the cutoff wavelength was about 3.8 μm at room temperature. The electron mobility at 300 K is higher than 2×10 4cm2/Vs. It indicates that the structure of InAs/GaSb prepared by LPE has a potential for mid-infrared devices.

Temperature dependence of photoluminescence property in BaIn2O4

The temperature-dependent photoluminescence (PL) spectra of BaIn2O4, prepared by coprecipitation, are measured and discussed. Aside from the reported 3.02-eV violet emission, the 1.81-eV yellow emission involved with oxygen vacancy is also observed at room temperature wherein the deep donor level is at 1.2 eV. With the temperature increasing, the peak energies for both emissions show a red shift. Moreover, the yellow emission intensity decreases while the violet emission intensity increases. The temperature dependence of the yellow emission intensity fits very well into the one-step quenching process equation, indicating a fitted activation energy at 19.2 meV.

Electronic transitions and hybrid resonance in InAsSb films by reflectance spectra

Electronic properties of InAs1−xSbx films with x up to 0.09 have been investigated by reflectance spectra in 1.5–5 eV energy range at room temperature. The real and imaginary parts of the dielectric function were derived by Kramers–Kronig analysis on the reflectance spectra, which show satisfactory agreement with the spectroscopic ellipsometry data. The E1′ and E1′+Δ1′ peaks are attributed to electronic interband transitions at the E1 and E1+Δ1 critical points, respectively. The prominent E2′ peaks, which exhibit high reflectivity and large blueshift, are found to be contributed by hybrid resonance due to the cooperative behavior of both E2-state electrons and plasmons.

Effects of annealing on InAsSb films grown by the modified LPE technique

We have studied the annealing effects on InAsSb thick films grown by the modified liquid phase epitaxy (LPE) technique. Appropriate annealing treatment can efficiently eliminate Sb vacancy and stain which are formed during growing process, thus it is necessary to study the influence of annealing condition (temperature, ambient, time and cooling rate) on the properties of InAsSb epilayer. The X-ray diffraction measurement (XRD) showed the annealed InAsSb films were polycrystalline with (111)-preferred orientation, except for the two samples annealed with 350 °C for 15 hours and with rapid cooling rate, respectively, which exhibited a (100)-preferred orientation. The Fourier transform infrared (FTIR) revealed a cut off wavelength more than 10 μm for the samples. Also, the infrared transmittance would be improved due to decreasing of film defects by appropriate annealing treatment. Measurement of electrical properties for samples revealed the increase of electron mobility and the reduce of carrier concentration at 77K when keeping anneal temperature low at 350 °C and extending anneal time, indicating the electrical improvement of the InAsSb layers.