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 In_1−xGa_xAs_yP_1−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.