As4 to Ga flux ratio dependence of the optical and electrical properties of Ge-doped GaAs grown by molecular-beam epitaxy

Abstract

A drastic change of the conduction type from p to n with an increase of the As4 to Ga flux ratio, γ, was observed for the first time in the photoluminescence spectra of amphoteric impurity (Ge)-doped GaAs made by molecular-beam epitaxy. The sample with the lowest γ (γ=1.0) presented a purely p-type emission associated with pairs between the excited states of acceptors. The sample with the highest γ (γ=10.6) indicated a totally n-type emission reflecting an increase of quasi Fermi energy. Results show that by precisely controlling the flux ratio, γ, one can reliably make use of substantially amphoteric atoms of Ge both as p- and n-type impurities for the fabrication of GaAs by molecular-beam epitaxy.