Two-dimensional XY monolayers (X = Al, Ga, In; Y = N, P, As) with a double layer hexagonal structure: A first-principles perspective

In this paper, we systematically investigate the structural, mechanical, optical and electronic properties of novel two-dimensional XY (X = Al, Ga, In; Y = N, P, As) monolayers in the double layer hexagonal structure (DLHS) using first-principles calculations. Our calculations show that single-layers of XY are stable, with the exception of GaP monolayer, which is unstable with its phonon spectrum containing negative frequencies. Also, the linear elastic parameters confirm the Born conditions for mechanical stability of XY monolayers and they are brittle structures. Most XY monolayers have indirect semiconductor characteristics with band gaps of 3.54 eV, 1.78 eV, 0.18 eV, 1.68 eV and 1.28 eV for AlN, GaN, InN, AlP, and AlAs monolayers. However the GaAs monolayer has a metallic character. The optical results indicate the InN and AlAs monolayers have ability to absorb the visible light spectra. We expect that our findings will point the way forward for the use of these structures in microelectronics and optoelectronics devices.

Automated summary

In this paper, the structural, mechanical, optical, and electronic properties of novel two-dimensional XY (X = Al, Ga, In; Y = N, P, As) monolayers in the double layer hexagonal structure (DLHS) were systematically investigated using first-principles calculations. The results showed that most XY monolayers were stable and had indirect semiconductor characteristics, except for GaP monolayer which was unstable. InN and AlAs monolayers were capable of absorbing visible light spectra.