The effect of temperature-dependent substrate decomposition on graphene for separable GaN growth

Abstract

Graphene has been adopted in III−V material growth since it can reduce the threading dislocations and the III−V epilayer can easily be separated from the substrate due to the weak chemical bond. However, depending on the substrate supporting the graphene, some substrates decompose in the III−V material growth environment, which results in the problem that no graphene remains. In this study, we investigated the influence of temperature-dependent substrate decomposition on graphene through an annealing process that resembles conventional growth conditions in metal–organic chemical vapor deposition (MOCVD). We also confirmed that Trimethylgallium, Hydrogen, and Ammonia gases do not directly affect the graphene loss through Gallium Nitride (GaN) growth on a graphene/sapphire. In addition, GaN grown on graphene/sapphire could separate, but GaN grown on a graphene/GaN template could not be separated due to GaN template decomposition and related graphene damage. Through further investigation for graphene/Gallium Arsenide, we deduced that the gallium generated by substrate decomposition does not play a major role in damage to the graphene but instead the nitrogen generated by substrate decomposition is closely related to it. These results suggest that it is very important to adopt a decomposition-free substrate that do not damage graphene during GaN growth in MOCVD.