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

Abstract

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 $2\mu \text{m}$ thick active region without any bias dependence. At 150 K, ${\text{R}}_0\text{A}$ of $5100\Omega {\text{cm}}^2$ and specific detectivity of $1.05\times {10}^{12}\text{cm}{\text{Hz}}^{0.5}/\text{W}$ are demonstrated for a 50% cutoff wavelength of $4.2\mu \text{m}$ . 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 $25°\text{C}$ compared to the homojunction photodiode. Infrared imaging using f/2.3 optics and an integration time of $10.02\text{ms}$ demonstrates a noise equivalent temperature difference of 11 mK at operating temperatures below 120 K.