Compensation mechanisms in n⁺-GaAs doped with sulphur

Abstract

S-doped GaAs, grown by organometallic vapor phase epitaxy, has been characterized from the viewpoint of compensation. Hall-effect and photoluminescence data at 10 K, in conjunction with secondary ion mass spectrometry and double crystal X-ray diffraction measurements, have been used to understand dopant-behavior with increasing concentration levels. It is shown that the compensation ration in S: GaAs increase with the doping level, from about 0.5 (rmNA-/ND+) for an electron concentration level of 1017 cm-3 to 0.91 at 3.8×1018cm-3, and is also a weak function of the V/III ratio and the growth rate. these results are explained using thermodynamic considerations for dopant-incorporation in GaAs. The unexpected absence of strain in heavily-doped S: GaAs is shown to be consistent with the presence, in sufficient concentration, of a complex involving the donor and an adjacent VGa. The results for S: GaAs are in agreement with the observation of superdilation in Te: GaAs. © 1989.