Kinetic limits to growth on (001) and (110) GaAs by OMCVD

Abstract

This paper summarizes results of our investigations of growth on (001) and (110) GaAs by atmospheric pressure organometallic chemical vapor deposition (OMCVD). We follow evolutions of surface species to a sensitivity of 0.01 monolayer (ML) on a time scale of 0.1 s under alternating flows of trimethylgallium (TMG) and arsine (AsH 3) as functions of partial pressure, sample temperature, and surface orientation. The reaction of TMG with an AsH 3-saturated (001) surface is rate-limited by competition between desorption and decomposition of TMG molecules chemisorbed to surface lattice sites via an exclude-volume mechanism, while the reaction of AsH 3 with the TMG-saturated (001) surface is essentially instantaneous. In contrast, TMG reacts essentially instantaneously with the AsH 3-saturated (110) surface while the AsH 3 reaction with the TMG-saturated (110) surface is the rate-limiting step. However, the latter rate is not intrinsic to the AsH 3-surface reaction but appears to be determined by desorption of adsorbed species that block active sites.