Gallium hydride-chloride-azide GaH(Cl)(N3) has been tested as a GaN CVD precursor at 500-600°C. GaN films grown at 500°C and lower, had small amount of Cl, while those grown at higher temperature (600°C) are Cl-contamination free. [427]
The molecular structure of this gallane is tetrameric: [HClGaN3]4 , with a heterocyclic cyclooctane-like structure. Single-crystal X-ray study reveals that the molecule consists of eight-membered Ga4N4 rings with Ga atoms bridged by the α-nitrogens of the azide groups. [HClGaN3]4 crystallizes in the tetragonal space group. On the basis of the mass spectrum, the vapor of the compound consists of the trimer [HClGaN3]3, which is a low-temperature molecular source for growth of GaN layers on sapphire and Si substrates at 500 °C. The compound decomposes exothermically at 70°C to yield bulk nanocrystalline wurtzite and zinc blende GaN.[430]