Subnanometer-thick 2D GaN film with a large bandgap synthesized by plasma enhanced chemical vapor deposition

Abstract

Two-dimensional (2D) GaN exhibits a wide bandgap, high quantum efficiency, and ultralow thermal conductivity, making it a promising candidate for optoelectronic and thermoelectric applications. In this study, we synthesize ultrathin 2D GaN films via an improved template method by plasma enhanced chemical vapor deposition (PECVD). Nitrogen gas, which is clean and environmentally friendly compared to the commonly used ammonia, is chosen to nitrogenize the Ga₂O₃ template layer. The transformation of the Ga₂O₃ layer into ultrathin 2D GaN has been demonstrated by a series of characterization studies. Furthermore, it is found that the soft N₂ plasma not only nitrogenizes the oxide template but also etches the unwanted upper layers to tailor the thickness of 2D GaN. Owing to its subnanometer thickness, the 2D GaN film exhibits a wide bandgap of ∼4.9 eV. This study provides an effective way to fabricate atomically thin GaN nanosheets with a wide bandgap for deep-ultraviolet applications.