Design of high-mobility p-type GaN via the piezomobility tensor

TL;DR

This paper introduces a systematic first-principles approach using a piezomobility tensor to enhance hole mobility in GaN through specific strain configurations, enabling significant mobility improvements for electronic applications.

Contribution

The study develops a novel tensor notation and first-principles methodology to analyze and optimize strain conditions for high hole mobility in GaN.

Findings

Identified three optimal strain configurations for mobility enhancement.

Predicted room-temperature hole mobility up to 164 cm^2/Vs under uniaxial compression.

Provided a general framework for strain effects on semiconductor transport properties.

Abstract

Gallium nitride (GaN) is a wide-bandgap semiconductor of significant interest for applications in solid-state lighting, power electronics, and radio-frequency amplifiers. An important limitation of this semiconductor is its low intrinsic hole mobility, which hinders the development of \textit{p}-channel devices and the large-scale integration of GaN CMOS in next-generation electronics. Prior research has explored the use of strain to improve the hole mobility of GaN, but a systematic analysis of all possible strain conditions and their impact on the mobility is lacking. In this study, we introduce a piezomobility tensor notation to characterize the relationship between applied strain and hole mobility in GaN. To map the strain-dependence of the hole mobility, we solve the \textit{ab initio} Boltzmann transport equation, accounting for electron-phonon scattering and GW quasiparticle energy corrections. We show that there exist three optimal strain configurations, two uniaxial strains and one shear strain, that can lead to significant mobility enhancement. In particular, we predict room-temperature hole mobility of up to 164~\mob\ for 2\% uniaxial compression and 148~\mob\ for 2\% shear strain. Our methodology provides a general framework for investigating strain effects on the transport properties of semiconductors from first principles.