Core properties and mobility of the basal screw dislocation in wurtzite GaN: a density functional theory study

We have performed first principles simulations, based on density functional theory (DFT), to investigate the core properties of the basal a-type screw dislocation in wurtzite gallium nitride. Our calculations demonstrate that the fully coordinated shuffle core configuration is the most energetically favourable. The calculated electronic structure of the a-type screw dislocation was found to exhibit exclusively shallow gap states which are not associated with any extended metallization. This may explain why a-type screw dislocations are less detrimental to the performance of GaN based electronic devices than c-type screw dislocations.