Comparison of structural and optical properties of GaSb/AlGaSb quantum well structures grown on different oriented Si substrates

We report on the molecular beam epitaxy (MBE) of GaSb films and GaSb/AlGaSb multiple quantum well (MQW) structures grown on Si(1 1 1) and Si(0 1 1) substrates using an AlSb initiation layer. The structural and optical properties of the films on the different oriented Si substrates were characterized by cross-sectional transmission electron microscopy (TEM), high-resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM), and photoluminescence (PL) measurements. The GaSb films and the MQW structures grown on Si(0 1 1) were found to have rather rough surfaces and of poor crystallinity under the present growth condition with the AlSb initiation layer. In contrast, the films grown on Si(1 1 1) indicated a mirror surface, definite MQW structures, and HRXRD patterns. The PL emissions within the 1.3-1.5 μm for the MQW structures on Si(1 1 1) and Si(0 1 1) were observed at the temperatures up to 300 and 200 K, respectively. We found that the PL peak energy, around 1.5 μm, of the MQW structures grown on Si(1 1 1) is almost temperature independent up to ∼120 K and exhibits a smaller variation with increasing temperature compared to those of the samples grown on Si (0 0 1) substrates. In the case of the MQW on Si (0 1 1), the PL peak energy as a function of temperature showed an intermediate behavior between those grown on Si(1 1 1) and Si(0 0 1) substrates.