The electronic and mechanical properties of two dimensional multilayered GaN: A first-principles study

GaN is a wide-bandgap semiconductor extensively used in electronic and optoelectronic fields. When its thickness is reduced to a few monolayers (MLs), it can even be used for nano-electronic and nano-optoelectronic devices due to the extreme quantum confinement. Undoubtedly, thickness is one of the most important factors for the properties of two-dimensional (2D) materials. Up to now, however, the influence of thickness on the electronic and mechanical properties of 2D GaN has not been systematically studied in experiment or theory. As we know, it is difficult to synthesis perfect 2D GaN with controllable thickness in experiment. Thus, in this paper, we study the stability, electronic and mechanical properties of 1-5 ML 2D GaN employing the density functional theory. It is found that the 1 ML GaN reconstructs into honeycomb structure and 2-5 ML GaN reconstruct into 8|4 Haeckelite structure. All structures are dynamically stable. Additionally, as the layer numbers increase, the inplane Young's modulus and layer modulus along armchair and zigzag direction monotonically increase, but bandgap decrease. All results indicate that electronic and mechanical properties can be modulated by changing layer numbers, which can provide guidance in design, manufacture, and integration of 2D GaN devices in the future.