Lattice Structure and Bandgap Control of 2D GaN Grown on Graphene/Si Heterostructures.

2D group-III nitride materials have shown a great promise for applications in optoelectronic devices thanks to their thickness-dependent properties. However, the epitaxial growth of 2D group-III nitrides remains a challenge. In this work, epitaxial growth of 2D GaN with well-controlled lattice structures and bandgaps is achieved by plasma-enhanced metal organic chemical vapor deposition via effective regulation of plasma energy and growth temperature. The structure of graphene/2D GaN/Si heterostructures is carefully investigated by high-resolution transmission electron microscopy. The formation mechanism of the 2D GaN layer is clearly clarified by theoretical calculations. Furthermore, a bandgap for 2D GaN ranging from ≈4.18 to ≈4.65 eV varying with the numbers of layers is theoretically calculated and experimentally confirmed. 2D GaN with well-controlled lattice structure and bandgap holds great potential for the development of deep ultraviolet light-emitting diodes, energy conversion devices, etc.