The influence of TMA and SiH4 on the incorporation rate of Ga in AlxGa1−xN crystals grown from TMG and NH3

Abstract

In an atmospheric pressure vertical reactor, with conditions designed to minimize predeposition of A1N (water-cooled walls), the growth rate of AlxGa1−xN grown from the TMG, TMA and NH3 decreases rapidly with substrate temperatures above 900°C. The aluminum mole fraction of these films increases with temperatures above 1000°C with other growth parameters fixed. Furthermore, the Ga incorporation rate decreases with increasing TMA input flux at fixed TMG input flux and substrate temperature. A surface kinetic model in which both A1 and Ga compete for the same surface sites and the thermally ativated desorption of Ga from the surface plays a key role has been developed to explain these results. Addition of small amounts of SiH4 (Si is a shallow donor in GaN) strongly reduces the incorporation rate of Ga but it does not affect that of A1.