Precise Radiative Lifetimes in Bulk Crystals from First Principles: The Case of Wurtzite GaN

TL;DR

This paper presents a first-principles method for accurately calculating radiative lifetimes in bulk uniaxial crystals, demonstrated on wurtzite GaN, with results aligning well with experimental data up to 100 K.

Contribution

The study introduces a comprehensive first-principles approach that includes excitonic effects and spin-orbit coupling to compute radiative lifetimes in anisotropic materials like GaN.

Findings

Computed lifetimes agree with experiments up to 100 K

Including excitons and spin-orbit coupling is essential

Modeling exciton dissociation extends calculations to room temperature

Abstract

Gallium nitride (GaN) is a key semiconductor for solid-state lighting, but its radiative processes are not fully understood. Here we show a first-principles approach to accurately compute the radiative lifetimes in bulk uniaxial crystals, focusing on wurtzite GaN. Our computed radiative lifetimes are in very good agreement with experiment up to 100 K. We show that taking into account excitons (through the Bethe-Salpeter equation) and spin-orbit coupling to include the exciton fine structure is essential for computing accurate radiative lifetimes. A model for exciton dissociation into free carriers allows us to compute the radiative lifetimes up to room temperature. Our work enables precise radiative lifetime calculations in III-nitrides and other anisotropic solid-state emitters.