A first-principles prediction of novel Janus ZrGeZ3H (Z = N, P, and As) monolayers: Raman active modes, piezoelectric responses, electronic properties, and carrier mobility

Abstract

In this article, an attempt is made to explore new materials for applications in piezoelectric and electronic devices. Based on density functional theory calculation, we construct three Janus ZrGeZ₃H (Z = N, P, and As) monolayers and study their stability, piezoelectricity, Raman response, and carrier mobility. The results from phonon dispersion spectra, ab initio molecular dynamics simulation, and elastic coefficients confirm the structural, thermal, and mechanical stability of these proposed structures. The ZrGeZ₃H monolayers are indirect band gap semiconductors with favourable band gap energy of 1.15 and 1.00 eV for the ZrGeP₃H and ZrGeAs₃H, respectively, from Heyd–Scuseria–Ernzerhof functional method. It is found that the Janus ZrGeZ₃H monolayers possess both in-plane and out-of-plane piezoelectric coefficients, revealing that they are potential piezoelectric candidates. In addition, the carrier mobilities of electrons and holes along transport directions are anisotropic. Notably, the ZrGeP₃H and ZrGeAs₃H monolayers have high electron mobility of 3639.20 and 3408.37 cm² V⁻¹ s⁻¹, respectively. Our findings suggest the potential application of the Janus ZrGeZ₃H monolayers in the piezoelectric and electronic fields.