Aspects of “High Minority-Carrier Lifetime” GaAs on Si Using A Novel SiGe/Ge Buffer

Abstract

Heteroepitaxial GaAs-on-Si utilizing a Si 0.4 Ge 0.96 /Ge buffer, with a hole minority-carrier lifetime as long as ∼ 2.5 nsec is described. This is the longest minority-carrier lifetime in GaAs grown on Si reported to date by any approach. Here we discuss the microstructural aspects of this heteroepitaxial system, including a crossectional transmission electron microscopy (XTEM) study of the interface of the SiGe/Ge buffer and the role of the SiGe layer. An x-ray double crystal diffraction (DCD) study of the GaAs layers is also presented. The SiGe/Ge buffer approach to heteroepitaxial GaAs on Si is a result of two observations: (1) SiGe epitaxial layers grown on Ge are under biaxial compressive stress (from DCD) and (2) dislocations tend to bend over into the Ge substrate (from TEM). These data and a description of the heteroepitaxy of SiGe layers on Ge are presented.