  Nitride semiconductors are ubiquitous in optoelectronic devices such as LEDs
and Blu-Ray optical disks. A major limitation for further adoption of GaN in
power electronics is its low hole mobility. In order to address this challenge,
here we investigate the phonon-limited mobility of wurtzite GaN using the ab
initio Boltzmann transport formalism, including all electron-phonon scattering
processes, spin-orbit coupling, and many-body quasiparticle band structures. We
demonstrate that the mobility is dominated by acoustic deformation-potential
scattering, and we predict that the hole mobility can significantly be
increased by lifting the split-off hole states above the light and heavy holes.
This can be achieved by reversing the sign of the crystal-field splitting via
strain or via coherent excitation the A$_1$ optical phonon through ultrafast
infrared optical pulses.
