Gallium vacancy complexes as a cause of Shockley-Read-Hall recombination in III-nitride light emitters

We describe a mechanism by which complexes between gallium vacancies and oxygen and/or hydrogen act as efficient channels for nonradiative recombination in InGaN alloys. Our identification is based on first-principles calculations of defect formation energies, charge-state transition levels, and nonradiative capture coefficients for electrons and holes. The dependence of these quantities on alloy composition is analyzed. We find that modest concentrations of the proposed defect complexes (∼1016 cm−3) can give rise to Shockley-Read-Hall coefficients A=(107−109) s−1. The resulting nonradiative recombination would significantly reduce the internal quantum efficiency of optoelectronic devices.