Epitaxy and Characterization of Ultrathin (10 nm) GaSb/AlSb Heterostructures Directly on Si(001)

In this study, we present a systematic optimization of 10 nm GaSb thin film grown directly on Si(001) substrate using a 5 nm AlSb buffer layer. By carefully tuning the AlSb buffer layer's growth temperature and thickness, growth conditions of 300 °C and 5 nm are identified that yield a smooth, two-dimensional 10 nm GaSb morphology with a root-mean-square (r.m.s.) surface roughness of 0.90 nm and an X-ray diffraction (XRD) full width at half-maximum (FWHM) of 0.76°. Cross-sectional transmission electron microscopy confirms the high-quality AlSb/GaSb interface and a minimal level of defect propagation through AlSb. In addition, micro-Raman spectroscopy and temperature-dependent Hall measurements reveal a slightly strained GaSb layer with a room-temperature hole mobility of approximately 350 cm²/(V·s). Furthermore, increasing the GaSb thickness to 300 nm improves surface quality and crystallinity, achieving an r.m.s. roughness of 0.40 nm and an FWHM of 0.39°. These results demonstrate the viability of integrating ultrathin, high quality GaSb layers on Si(001), showing their potential for scalable, high performance applications in next-generation CMOS-compatible micro/nanoelectronic devices.