Trap-assisted Non-radiative Recombination of C_N in GaN

The efficiency of optoelectronic devices is often constrained by trap-assisted non-radiative recombination. The conventional multiphonon emission process falls short in describing the measured nonradiative recombination rate for wider-band-gap semiconductors due to its negligibly small rate in materials with band gaps greater than 2.5 eV. It has been suggested that trap-assisted Auger-Meitner (TAAM) recombination can resolve this discrepancy [1]. In TAAM processes, a free electron or hole recombines with a defect state, exciting a second carrier to a higher energy state. C_N impurities in GaN are commonly introduced during the metal-organic chemical vapor deposition (MOCVD) growth process. While C_N has been suggested to be a nonradiative recombination center, the complete recombination cycle has not been described, particularly regarding the influence of the (+/0) level. Implementing our recently developed first-principles methodology [1], we investigate the TAAM process of C_N in GaN in addition to the multiphonon capture process for both the (+/0) and (0/-) levels. Furthermore, we study the impact of thermal emission on the overall recombination rate. We find that re-emission of holes from C+ N into the valence band has significant impact on the overall rates at lower carrier densities.