Growth and Characterization of SiGe on c-Plane Sapphire Using a Chemical Vapor Deposition System

Silicon–germanium (SiGe) films have been grown using chemical vapor deposition on c-plane sapphire substrates. Optical and material characterization of the films show successful alloying of SiGe up to 22.4% Si. X-ray diffraction characterizations show that the SiGe films are oriented in the (111) direction on the sapphire (0001) substrates. However, 60°-rotated twin defects are observed as well. Transmission electron microscopy (TEM) shows crystalline growth of the film. The high surface roughness observed in the TEM images and the atomic force microscopy scans of the films indicates the formation of two different orientations of SiGe on sapphire substrates.