# Route to high hole mobility in GaN via reversal of crystal-field splitting

## TL;DR

This study uses ab initio calculations to show that reversing crystal-field splitting in GaN can significantly enhance hole mobility, potentially enabling better p-channel transistors.

## Contribution

It demonstrates that applying biaxial tensile strain can increase GaN hole mobility by reversing crystal-field splitting, a novel approach for improving device performance.

## Key findings

- Biaxial tensile strain of 2% increases hole mobility by 230%.
- Predicted room temperature hole mobility up to 120 cm²/Vs.
- Reversing crystal-field splitting lifts split-off hole states above light and heavy holes.

## Abstract

A fundamental obstacle toward the realization of GaN p-channel transistors is its low hole mobility. Here we investigate the intrinsic phonon-limited mobility of electrons and holes in wurtzite GaN using the ab initio Boltzmann transport formalism, including all electron-phonon scattering processes and many-body quasiparticle band structures. We predict that the hole mobility can be increased by reversing the sign of the crystal-field splitting, in such a way as to lift the split-off hole states above the light and heavy holes. We find that a 2% biaxial tensile strain can increase the hole mobility by 230%, up to a theoretical Hall mobility of 120 cm$^2$/Vs at room temperature and 620 cm$^2$/Vs at 100 K.