High-quality GaN grown on nitrogen-doped monolayer graphene without an intermediate layer

GaN on graphene/Al2O3 substrates grown via van der Waals epitaxy compensates for the deficiencies and defects caused by metal-organic chemical vapor deposition (MOCVD) on substrates with significant mismatches to GaN. However, the absence of dangling bonds on graphene leads to insufficient nucleation sites; hence, a thin layer of AlN or ZnO nanowalls should be deposited on graphene as an intermediate layer. In this work, high-quality GaN crystals with a low biaxial compressive stress of 0.023 GPa and low screw dislocation density of 9.76 x 10(7) cm(-2) were successfully synthesized by MOCVD on nitrogen-doped graphene without a buffer layer. First-principles calculations demonstrated significant improvement in the adsorption energy of the Ga atom on the surface of nitrogen-doped graphene compared with that of pristine graphene, in agreement with the experimental observations of nucleation. In most cases, GaN films were obtained by forming C-Ga-N and N-Ga-N configurations via atomic nitrogen pretreatment on monolayer graphene. Therefore, it is hoped that the efficient method of atomic modulation of high-quality GaN films grown on nitrogen-doped graphene via interface manipulation used in this work will promote the industrial development of innovative semiconductor devices.

Automated summary

GaN on graphene/Al2O3 substrates compensates for the defects caused by MOCVD on mismatched substrates. An intermediate layer of AlN or ZnO nanowalls is needed to provide sufficient nucleation sites on graphene without dangling bonds. High-quality GaN crystals with low compressive stress and dislocation density were successfully synthesized on nitrogen-doped graphene by MOCVD. The improved adsorption energy of Ga atom on nitrogen-doped graphene and atomic nitrogen pretreatment on monolayer graphene contribute to the nucleation of GaN films.