Enhancing InSe monolayer via full hydrogenation: insights into electronic structure, piezoelectricity, and charge mobility

Abstract

Functionalization is a widely employed method to enhance the performance of InSe monolayers. However, the impact of atomic adsorption on their electronic and related properties often remains incompletely explored. In this study, we propose a fully hydrogenated 2H–InSe monolayer and utilize first-principles calculations to comprehensively investigate the effects of full hydrogenation on its structural, electronic, piezoelectric, and transport characteristics. Our calculations confirm the dynamic and mechanical stability of this monolayer, exhibiting a Young’s modulus of 53.43 N m⁻¹ and a Poisson’s ratio of 0.31. In contrast to pristine InSe, the hydrogenated monolayer possesses a larger direct bandgap. Furthermore, the 2H–InSe monolayer demonstrates promising piezoelectric properties, with a piezoelectric coefficient e₁₁ of 1.53 × 10⁻¹⁰ cm⁻¹ and d₁₁ of 3.75 pm V⁻¹. The charge carrier mobility is influenced by polar optical phonon (POP), ionized impurity (IMP), acoustic deformation potential (ADP), and piezoelectric (PIE) scattering mechanisms. POP scattering dominates at a low carrier concentration of 10¹⁶ cm⁻³, while IMP scattering becomes dominant at a high carrier concentration of 10²⁰ cm⁻³. The calculated total electron and hole mobilities are 546.55 cm² V⁻¹ s⁻¹ and 93.21 cm² V⁻¹ s⁻¹, respectively, which decrease to 45.55 cm² V⁻¹ s⁻¹ and 6.51 cm² V⁻¹ s⁻¹ as the temperature increases from 50 K to 400 K. Although charge carrier mobilities are low at high concentrations, 7.16–11.58 cm² V⁻¹ s⁻¹, their magnitude is well maintained with increasing temperature.