The effect of absorber doping on electrical and optical properties of nBn based type-II InAs/GaSb strained layer superlattice infrared detectors

We have investigated the electrical and optical properties of a nBn based InAs/GaSb strained layer superlattice detector as a function of absorber region background carrier concentration. Temperature dependent dark current, responsivity, and detectivity were measured. The device with a nonintentionally doped absorption region demonstrated the lowest dark current density with a specific detectivity at zero bias equal to 1.2×10¹¹ cm Hz^1/2/W at 77 K. This value decreased to 6×10¹⁰ cm Hz^1/2/W at 150 K. This contrasts significantly with p-i-n diodes, in which the D^* decreases by over two orders of magnitude from 77 to 150 K, making nBn devices promising for higher operating temperatures.