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 $2μm$ thick active region without any bias dependence. At 150 K, $R0A$ of $5100Ωcm2$ and specific detectivity of $1.05×1012cmHz0.5/W$ are demonstrated for a 50% cutoff wavelength of $4.2μm$⁠. Assuming 300 K background temperature and $2π$ field of view, the performance of the detector is background limited up to 180 K, which is improved by $25°C$ compared to the homojunction photodiode. Infrared imaging using f/2.3 optics and an integration time of $10.02ms$ demonstrates a noise equivalent temperature difference of 11 mK at operating temperatures below 120 K.