Effects of hydrogen on GaN metalorganic vapor-phase epitaxy using tertiarybutylhydrazine as nitrogen source

Abstract

Gallium nitride (GaN) layers have been synthesized from mixtures of trimethylgallium, tertiarybutylhydrazine (TBHy), and hydrogen (H 2) at 958 K using the metalorganic vapor-phase epitaxy technique. The role of H 2 in the reaction system is explored by investigating the film property changes at various H 2 concentrations. Epitaxial growth of GaN with carbon incorporation less than 3 mol% is accomplished at a low H 2 concentration of 20 mol%, while it turns gradually into polycrystalline growth with high amount of carbon incorporation when the H 2 concentration is increased up to 90 mol%. Density functional theory calculations are performed to examine the thermochemistry of the H 2 elimination reaction of gaseous TBHy on Ga-terminated GaN surface. The result suggests that at high H 2 concentrations, a C–N containing species derived from TBHy due to incomplete β-hydride elimination may be ascribable to the appearance of polycrystalline phase and high amount of carbon incorporation.