Midinfrared type-II InAs/GaSb superlattice photodiodes toward room temperature operation

We study midinfrared type-II InAs/GaSb superlattice p-i-n photodiodes for high temperature operation. Representative samples exhibit a 3.9 mu m cutoff wavelength at 250 K and detectivity of 4.9x10(13), 1.0x10(10), and 2.4x10(9) cm Hz(1/2)/W at 78, 240, and 300 K, respectively. Longer-wavelength devices exhibit a 5.2 mu m cutoff wavelength at 240 K, and detectivity of 1.3x10(13) and 1.5x10(9) cm Hz(1/2)/W at 78 and 240 K, respectively. The electron beam induced current technique is used to investigate the spatially varying carrier collection efficiency contribution to the quantum efficiency at different biases and temperatures. The residual doping in the i region is determined to be 6.0x10(13) cm(-3) (n type) at 78 K. The prospect of operating focal plane arrays based on the sample studied around 240 K is quite promising. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2949744]