A Study of Silicon Incorporation in GaAs MOCVD Layers

Abstract

The incorporation of silicon in GaAs layers grown by metal-organic chemical vapor deposition has been studied using two different doping sources, silane and disilane. Epitaxial ayers were grown on <100>, < l l l>A, and < l l l>B surfaces over a wide range of growth temperature and gas phase stoichiometry. When using silane, an influence of the substrate orientation on silicon incorporation was found. This behavior can be described by a qualitative model involv-ing both the surface specific adsorption sites and possible surface chemical reactions. In the case of disilane, the incor-poration process appears to be independent of substrate orientation and growth temperature. This temperature inde-pendence results in improved uniformity of the electron concentration over large substrate areas when disilane is used as the doping gas. Silicon is commonly used as a dopant for the growth of n-type GaAs and AlxGa, xAs layers in metal-organic chemical vapor deposition (MOCVD) (1-3) and in molecu-lar beam expitaxy (MBE) (4). The low volatility and low diffusion coefficient of silicon in GaAs are properties which make this dopant especially useful for the deposi-