Minority carrier lifetime characteristics in type II InAs/GaSb LWIR superlattice n⁺πp⁺photodiodes

Abstract

In this work the current versus voltage data of a p-n+ junction is converted into minority carrier lifetime data. Space charge recombination currents dominate at modest reverse bias at 80K and taking the dominant recombination centers to be located at the intrinsic Fermi level, the lowest minority carrier lifetime τ₀ is determined to be 35ns. This single Shockley-Read-Hall carrier recombination parameter provides an excellent fit to the data over temperature range 40K≤ T≤ 130K; the 35ns minority carrier lifetime also explains the quantum efficiency data. The transition from diffusion to space charge currents occurs for temperatures, T ≤ 100K. For T≤ 40K trap assisted tunneling is the dominant current component. Based on imaging system requirements to be near background limited for photon flux ≈ 10¹⁵ ph/cm²-s and detector temperature of 80K, the minority carrier lifetime will need to be increased by one order of magnitude.