A novel two-dimensional δ-InP3 monolayer with high stability, tunable bandgap, high carrier mobility, and gas sensing of NO2

Abstract

Based on ab initio density functional theory calculations and by using the global optimization algorithm, we propose a novel two-dimensional (2D) InP₃ allotrope (δ-InP₃ monolayer), which has much lower formation energy and exfoliation energy than those of the earlier known β-InP₃ monolayers. The δ-InP₃ monolayer has an indirect bandgap of 0.51 eV, which could be easily tunable by adjusting the strains along the a direction. Our calculations reveal that this new InP₃ allotrope exhibits worthwhile anisotropy along with high electron carrier mobility. The electron mobility of the δ-InP₃ monolayer can reach up to 2741 and 1751 cm² V⁻¹ s⁻¹ along the a and b directions, respectively. The absorption coefficients for the δ-InP₃ monolayer and bilayer are predicted up to the order of ∼10⁶ cm⁻¹ in the entire visible region. More interestingly, the calculated results show that the δ-InP₃ monolayer is a promising N-based gas sensor (particularly for NO₂ molecules), with high selectivity, sensitivity, and good reversibility.