Pressure-induced phase transition and indirect band gap semiconductor in ZnSnN2: First Principles Calculation

In this study, we investigate the phase transition of ZnSnN₂ from Pna2₁ to Pmnb using Density Functional Theory (DFT) across a pressure range of 0–70 GPa. Our results show the enthalpy intersection of the Pna2₁ and Pmnb phases at 19.28 GPa, indicating a phase transition from Pna2₁ to Pmnb ZnSnN₂. The decrease in H_v of the Pna2₁ phase under pressure before the phase transition is attributed to the reduction of the G and weakening covalent bond of Sn–N pair. The new Pmnb phase exhibits an increased Vickers hardness, Debye temperatures, and brittleness. Moreover, the band gap is an indirect band gap of 1.41 eV due to a rearrangement of lower energy levels for Sn s and p states in conduction band minimum (CMB) and N s and p states in valence band maximum (VBM) at Γ-point. These characteristics make The Pmnb phase promising candidates for applications were longer carrier lifetimes are needed. The mechanical properties, dynamical behavior, and electron localization functions (ELFs) have been investigated and discussed.