Temperature dependence of dark current measurements is an efficient way to verify the quality of an infrared detector. Low dark current density values are needed for high performance detector applications. Identification of dominant current mechanisms in each operating temperature can be used to extract minority carrier lifetimes which are highly important for understanding carrier transport and improving the detector performance. InAs/AlSb/GaSb based T2SL N-structures with AISb unipolar barriers are designed for low dark current with high resistance and detectivity. Here we present electrical and optical performance of such N-structure photodetectors. (C) 2016 Elsevier Ltd. All rights reserved.