Evaluation of lateral diffusion length in InAs/GaSb superlattice detectors grown by MOCVD

Abstract

The lateral diffusion length (L h) of minority carriers in LWIR InAs/GaSb superlattice detectors grown by metalorganic chemical vapour deposition was evaluated. The deeply-etched PNn device exhibits a diffusionlimited behaviour at 80 K, with a dark current density as low as 9.1 × 10 −6 A/cm 2 at −0.1 V and a 50% cutoff of 10.1 μm. In shallowetched pixels with a common absorber, both the photo-current and the dark current show a size-dependent behaviour. L h deduced from the two methods are 211 and 251 μm, respectively, which are longer than those in superlattice materials grown by molecular beam epitaxy.