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 photo luminescence (PL) measurements. The GaSb films and the MQW structures grown on Si(0 1 1) were found to have rather tough 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 mu m 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 mu m, of the MQW structures grown on Si(1 1 1) is almost temperature independent up to similar to 120 K and exhibits a smaller variation with increasing temperature compared to those of the samples grown on Si (0 1 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 1 1) substrates. (C) 2008 Elsevier B.V. All rights reserved.