Auger recombination in InAs: Role of spin-orbit coupling and phonons

Indium arsenide (InAs), with a low band gap of 0.35 eV, is used in long-wavelength photo-detectors, lasers, photovoltaic junctions and a host of other semiconductor devices. Very high Auger recombination coefficients (ranging from 10⁻²⁷∼10⁻²⁶ cm⁶s⁻¹) have been measured in this material. Here, we present first-principles-based investigations of Auger recombination processes in InAs. For the direct process, we calculate an Auger coefficient of 1.6 × 10⁻²⁷ cm⁶s⁻¹; for the indirect phonon-assisted process, the coefficient is 1.7 × 10⁻²⁹ cm⁶s⁻¹. Our results elucidate the role of strong spin-orbit coupling: in InAs, the spin-orbit splitting of the valence band is close in magnitude to the band gap, allowing for efficient excitation of Auger holes and leading to a significant enhancement of the Auger recombination coefficient.