Growth methods for high purity Ge and Ge: Ga homoepitaxy

Abstract

The intent of this article is to provide methods to prepare Ge and Ge: Ga homoepitaxy with residual group III and V impurity concentrations below 1013 cm-3. Methods for growing high purity Ge and Ge: Ga epitaxy have not been previously established. However, high purity layers of these types are required for fabricating a new type of far-infrared photon detector. The growth methods described here employ the halides of germanium (GeCl4) and of gallium (GaCl3) as sources in chemical vapor deposition. The undoped Ge epitaxy prepared contains residual impurity concentrations below our sensitivity limit of 2 X 1013 cm-3. The undoped growth method is modified to prepare Ge: Ga epitaxy with a measured residual donor concentration of 5 X 1012 cm-3.