The case for Auger recombination in In1−xGaxAsyP1−y

Abstract

The possible Auger recombination mechanisms in direct-gap semiconductors are investigated. These include band-to-band processes, phonon-assisted processes, and Auger recombination via shallow traps. The band-to-band Auger rates are calculated including Fermi statistics, nonparabolic bands, and screening effects both for n-type and p-type semiconductors. The nonparabolicity is calculated using the Kane-band model. The band-to-band Auger processes are characterized by a strong temperature dependence, the Auger rate decreasing rapidly with decreasing temperature. The phonon-assisted and the trap processes do not exhibit such a strong temperature dependence. This is because the additional momentum conservation for the four-particle states in band-to-band processes gives rise to a ’’threshold energy’’ for the process. For the same reason, the band-to-band Auger rate decreases rapidly with increasing band gap. In large-band-gap semiconductors the weakly temperature-dependent phonon-assisted processes are expected to dominate. The Auger recombination rate via shallow-trap levels increases with increasing trap depth. A numerical computation is carried out for the quaternary alloy In1−xGaxAsyP1−y. We find that the calculated Auger rate is significant enough to account for the observed temperature dependence of threshold current of 1.3- and 1.55-μm InGaAsP-InP double heterostructure lasers.