ACS Appl. Mater. Interfaces 7, 4504–4510 (2015)

Credit: AMERICAN CHEMICAL SOCIETY

Gallium nitride is a large-bandgap semiconductor widely used in blue light-emitting diodes and lasers. However its crystal quality, which influences the performance of the devices based on this material, is limited by structural defects. Such defects arise as a result of the lattice mismatch between the substrate and the epitaxially grown GaN layers. Lei Zhang and colleagues now demonstrate that the deposition of 2D nanosheets of graphene or hexagonal boron nitride on a first layer of GaN limits the propagation of such defects in the layers grown subsequently. In fact, GaN nucleates only on the areas that are not covered by these nanosheets and then epitaxially grows in the lateral directions forming a complete layer. In this way, the defects underneath the 2D materials do not affect the crystal structure of the uppermost GaN layer. The improved quality of the semiconductor is confirmed by the increased light output of light-emitting diodes fabricated with this approach.