Hole mobility of strained GaN from first principles

Poncé, Samuel [UCL] Jena, Debdeep [School of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14853, USA] Giustino, Feliciano [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom]

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 of the A1 optical phonon through ultrafast infrared optical pulses.