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

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.