Molecular Beam Epitaxial Growth and Characterization of InSb and InAsxSb1−x

Abstract

ABSTRACTLayers of InSb and InAsxSb1-x were grown on GaAs and GaAs on Si substrates and then characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) to determine the epilayer quality. Hall-effect measurements and photoluminescence (PL) were also performed. Single-crystal XRD indicated that the 5-μm InSb layers grown on GaAs had a peak full width at half maximum (FWHM) of 120 arc sec for the (004) reflection. Planar TEM of a 7-μm-thick InSb layer on GaAs(001) indicated a dislocation density of 2 x 106 cm−2 at the top of the layer. Hall effect measurements of an undoped 3.5-μm-thick InSb on semi-insulating GaAs indicated an electron density of 3.7 x 1016 cm−3 at 300K and a mobility of 45,000 cm2 / V-sec. At 77K these values were 2.7 x 1016 cm−3 and 49,200 cm2 / V-sec, respectively. The composition of the InAsxSb1-x was a function of the growth temperature and the As2/In ratio for both Sb2 and Sb4. The XRD (004) peak FWHM increased with the x value, indicating a deterioration in material quality. This may be caused by alloy segregation in InAsxSb1-x. The peak FWHM rapidly increases from x=0.1 to x=0.3 and then its value drops, indicating that the quality of the layers improved. InSb layers displayed a strong PL whereas the PL for the InAs0.5Sb0.5 layers was very weak. We also grew InSb and InAsxSb1-x layers on GaAs on Si. Optical transmission measurements on InSb indicated that the layers were under tensile stress. We believe this tensile stress could be used to lower the bandgap of InAsxSb1-x layers to provide longer cut-off wavelengths for infrared detectors.