Cause of the High Pesistance Region at Vapour Epitaxial GaAs Layer-Substrate Interface

Abstract

A trial is made to clarify the cause of the high resistance region at the interface between the GaAs substrate and the epitaxial layer grown by the Ga/AsCl₃/H₂ process. Layers were grown under conditions (a) the temperature of the substrate is changed during the growth run and (b) excess arsenic vapor is introduced at the beginning of the growth. In layers grown under high arsenic vapor pressure, the high resistance region does not exist and instead a very thin low resistance region appears at the interface. Such phenomena are qualitatively interpreted as due to the deviation of arsenic vapor pressure from that in the steady state condition in the reaction system. Hall measurement on the high resistance region at different temperatures shows that the high resistance is due to deep acceptors whose energy level is approximately 0.5 eV from the valence band edge and which are inferred to be related with arsenic vacancy.