Minority Carrier Lifetime in Beryllium-Doped InAs/InAsSb Strained Layer Superlattices

Minority carrier lifetimes in undoped and Beryllium-doped Type-2 Ga-free, InAs/InAsSb strained layer superlattices (SLS) with energy gaps as low as 0.165 eV were determined from photoluminescence kinetics. The minority carrier lifetime of 450 ns at 77 K in the undoped SLS confirms a high material quality. In similarly-grown structures that were p-doped to N _A = 6 × 10¹⁶ and 3 × 10¹⁷ cm⁻³, electron lifetimes of τ _n = 45 ns and 8 ns were measured. The 6 × 10¹⁶ cm⁻³ doping level is a factor of 6 greater than the typical background doping level in long-wave infrared (LWIR) Ga-containing InAs/GaSb SLS with similar bandgap and electron lifetime. This suggests that LWIR photodetectors with InAs/InAsSb SLS absorbers can be designed with smaller minority carrier concentrations and diffusion dark current densities. A relatively slow decrease of the lifetime with doping suggests a minor role of Auger recombination in the studied Ga-free SLS at T = 77 K with p-doping up to mid-10¹⁷ cm⁻³ level.