Structural evolution and characterization of heteroepitaxial GaSb thin films on Si(111) substrates

Abstract

This paper describes the structural evolution and characterization of heteroepitaxial GaSb thin films on Si(111) substrates. The growth process used a combination of atomic sources which included the rf sputtering of Sb and the thermal effusion of Ga. The formation of crystalline GaSb thin films required that initially a monolayer thick Sb buffer layer be applied directly to a clean H-passivated Si(111) substrate surface. The resulting film was characterized by high resolution x-ray diffraction, Rutherford backscattering spectrometry, transmission electron microscopy, secondary ion mass spectroscopy, and atomic force microscopy (AFM). The AFM images were taken from the material after several periods of growth to determine the evolution of crystal structure with thickness. Atomic force microscopy images of the film surface showed that the heteroepitaxial layers were formed via the Stranski-Krastanov growth mechanism. This result is consistent with the heteroepitaxial growth of systems representing large differences in lattice constant. The hole mobility and carrier concentration in the deposited material were determined by the Hall measurement, performed at room temperature and on a 140nm thick sample, to be 66cm2∕Vsec and 3×1019cm−3, respectively. The carrier mobility was relatively low as expected for measurements taken at room temperature.