Band gap renormalization and indirect optical absorption in MgSiN$_2$ at finite temperature

TL;DR

This study uses first-principles calculations to analyze how temperature affects the electronic and optical properties of MgSiN$_2$, revealing significant band gap reduction and red-shift in absorption with increasing temperature, aiding optoelectronic applications.

Contribution

It provides the first detailed analysis of temperature effects on MgSiN$_2$'s band structure and optical absorption, including electron-phonon interactions and band gap renormalization.

Findings

Electron-phonon coupling reduces the indirect band gap.

Band gap renormalization aligns calculations with experimental data.

Optical absorption onset shifts to lower energy with temperature.

Abstract

We investigate the temperature effect on the electronic band structure and optical absorption property of wide-band-gap ternary nitride MgSiN$_2$ using first-principles calculations. We find that electron-phonon coupling leads to a sizable reduction in the indirect gap of MgSiN$_2$, which is indispensable in understanding the optoelectronic properties of this material. Taking the band gap renormalization into account, the band gap of MgSiN$_2$ determined by the quasiparticle GW0 calculations shows good agreement with recent experimental result. The predicted phonon-assisted indirect optical absorption spectra show that with increasing temperature the absorption onset undergoes a red-shift. Our work provides helpful insights to the nature of the band gap of MgSiN$_2$ and facilitates its application in ultraviolet optoelectronic devices.