High operating temperature midwave infrared photodiodes and focal plane arrays based on type-II InAs/GaSb superlattices

The dominant dark current mechanisms are identified and suppressed to improve the performance of midwave infrared InAs/GaSb type-II superlattice photodiodes at high temperatures. The optimized heterojunction photodiode exhibits a quantum efficiency of 50% for 2 mu m thick active region without any bias dependence. At 150 K, R(0)A of 5100 Omega cm(2) and specific detectivity of 1.05 x 10(12) cm Hz(0.5)/W are demonstrated for a 50% cutoff wavelength of 4.2 mu m. Assuming 300 K background temperature and 2 pi field of view, the performance of the detector is background limited up to 180 K, which is improved by 25 degrees C compared to the homojunction photodiode. Infrared imaging using f/2.3 optics and an integration time of 10.02 ms demonstrates a noise equivalent temperature difference of 11 mK at operating temperatures below 120 K. (C) 2011 American Institute of Physics. [doi:10.1063/1.3573867]