Mass-spectrometric determination of antimony incorporation during III–V molecular beam epitaxy

Abstract

The antimony incorporation rate α(Sb) during molecular beam epitaxy (MBE) of GaAs1−ySby, AlAs1−ySby, and Al0.5Ga0.5As1−ySby is determined as a function of growth conditions via mass-spectrometric measurements of the nonincorporated fraction of the incident antimony flux. The observed trends of an increase in Sb incorporation rate with decreasing substrate temperature and increasing group III flux, and an increase in resulting Sb content with Sb flux, are found to be in agreement with previous studies using ex situ techniques only. Additionally, the process of GaAsSb on GaAs interface formation is shown to result in a time dependent α(Sb) and is understood on the basis of a surface Sb-content dependent Sb desorption rate. Similarly, the Sb desorption rate is found to be time dependent when an incoming Sb flux reacts with a growth interrupted GaAs surface to form a GaAsSb surface layer which is likely to be graded in composition.