Crystallinity and morphology of InSb epitaxial layers grown on GaSb by MOVPE using TDMASb and TMSb as Sb precursors

Abstract

High resolution X-ray diffraction (HRXRD), scanning probe microscopy (SPM), scanning electron microscopy (SEM), and optical microscopy measurements have been used for the crystallinity and morphological evaluation of epitaxial layers of InSb which were deposited on GaSb substrate using various V/III ratios and growth temperatures. Trimethylindium (TMIn) was used as indium source, while trisdimethylaminoantimony (TDMASb) and trimethylantimony (TMSb) were used comparably as antimony (Sb) source. Analysis of the micrographs obtained from the samples indicates that the thickness and quality of the deposited InSb layers are highly susceptible to changes in growth temperatures and V/III ratio regardless of the Sb source used. Fairly flat surfaces and optimum rms roughness values of 0.63 nm and 0.84 nm over 5 μm2 (relative to the rms roughness of 0.42 nm for the GaSb substrate) was achieved for the growth of InSb layers using values of V/III ratio which is ≈ 1.0 with growth temperatures of 480 °C and 425 °C for TMSb/TMIn and TDMASb/TMIn precursors respectively. The higher values of full width at half maximum (FWHM) from XRD patterns obtained for InSb layers deposited using TDMASb compared to TMSb indicates an improvement in crystallinity for the InSb layers deposited using TMSb as Sb source.