A study of the mechanism of the reaction of trimethylgallium with hydrogen selenide

Abstract

A study of the pre-deposition room temperature gas-phase reactions involved in the growth of Ga ₂ Se ₃ (and/or GaSe) using trimethylgallium (GaMe ₃ ) and hydrogen selenide (H ₂ Se) was undertaken, using a simple mass spectrometric sampling system on a conventional atmospheric pressure MOCVD reactor. The experimental studies were complemented by theoretical quantum chemical calculations which were used to predict the reaction thermochemistry and kinetics of the proposed reaction scheme. We have shown that the gas phase reaction of the GaMe ₃ –H ₂ Se mixture can be described by a simple reaction mechanism with no need for the participation of a stable Lewis acid–base adduct, although a transient adduct type species may be involved. The effect of the room temperature reaction of GaMe ₃ with H ₂ Se on the growth mechanism of Ga ₂ Se ₃ /GaSe and its role in determining epilayer morphology and microstructure are also discussed.