Nicholas Maung, Guanghan Fan, Tat-Lin Ng, John O. Williams and Andrew C. Wright
A study of the pre-deposition room temperature gas-phase reactions involved in the growth of Ga2Se3 (and/or GaSe) using trimethylgallium (GaMe3) and hydrogen selenide (H2Se) 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 GaMe3–H2Se 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 GaMe3 with H2Se on the growth mechanism of Ga2Se3/GaSe and its role in determining epilayer morphology and microstructure are also discussed.