The influence of lattice oxygen on the initial growth behavior of heteroepitaxial Ge layers on single crystalline Pr O2 (111) Si (111) support systems

Abstract

A combined structure and stoichiometry study on the growth behavior of single crystalline Ge(111) layers on Pr O2 (111) Si (111) heterostructures is presented. Ex situ x-ray diffraction techniques indicate that the interaction between Ge and Pr O2 (111) results in a complete reduction of the buffer oxide to a cubic Pr2 O3 (111) film structure. In situ reflection high energy electron diffraction, x-ray and ultraviolet photoelectron spectroscopy studies demonstrate that this chemical reduction of the oxide support occurs during the initial Ge growth stage. The interaction of Pr O2 with Ge results in the formation of an amorphous Ge oxide layer by the diffusion of lattice oxygen from the dielectric to the forming semiconductor deposit. After the complete conversion of Pr O2 to cubic Pr2 O3, the supply of reactive lattice oxygen is exhausted and the continuous Ge deposition reduces the initially formed amorphous Ge O2 -like film to GeO. The sublimation of volatile GeO uncovers the single crystalline cubic Pr2 O3 (111) film surface which provides a thermodynamically stable template for elemental Ge heteroepitaxy. A Volmer-Weber growth mode is observed which results after island coalescence in the formation of atomically smooth, single crystalline Ge(111) layers. © 2008 American Institute of Physics.