Graphene-Assisted Epitaxy of High-Quality GaN Films on GaN Templates

Graphene (Gr)-assisted epitaxy of semiconductors has been demonstrated as a revolutionary strategy for the fabrication of nitride materials and flexible devices. However, till now, most of the GaN epitaxy assisted by Gr is performed on thermally stable foreign substrates because Gr suffers obvious deterioration due to the decomposition of GaN substrate. Thus, large lattice and thermal mismatches still exist and inevitably lead to a high density of dislocations in nitrides. To address this issue, here, the Gr-assisted epitaxy of high-quality GaN films on GaN templates is demonstrated by constructing specially designed self-organized defective (SOD) Gr as a buffer layer. The SOD Gr allows for the spontaneous relaxation of strain in GaN epilayers by weakening the interfacial interactions; and thus, blocks the upward spread of threading dislocations in GaN templates. Therefore, screw and edge dislocation densities in GaN epilayers show reductions of 51% and 62%, respectively, compared to that in homoepitaxy. Based on the GaN film grown on SOD Gr, the as-fabricated blue light-emitting diode exhibits a 17% enhancement of light output power and a better emission wavelength stability than that without Gr. This work opens a practical pathway for the growth of high-quality nitrides and manufacturing of high-performance nitride-based devices.

Automated summary

This study demonstrates the growth of high-quality GaN films by using specially designed self-organized defective graphene (SOD Gr) as a buffer layer on GaN templates. The SOD Gr allows for the relaxation of strain in GaN epilayers and blocks the upward dispersion of dislocations in GaN templates.