InAs/GaAsSb Type-II Superlattice LWIR Focal Plane Arrays Detectors Grown on InAs Substrates
Min Huang, Jianxin Chen, Zhicheng Xu, Jiajia Xu, Zhizhong Bai, Fangfang Wang, Yi Zhou, Aibo Huang, Ruijun Ding, He Li
Abstract
InAs/GaAsSb type-II superlattice (T2SL) materials grown at a higher temperature and lattice-matched to InAs substrates are considered to have significant advantages in long wavelength infrared (LWIR) detection. In this work, an InAs/GaAsSb T2SL LWIR focal plane array (FPA) was fabricated and evaluated. The FPA has a format of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$320\times256$ </tex-math></inline-formula> with a pixel pitch of 30 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> and exhibits a 100% cutoff wavelength of 9.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> at 80 K. Under a bias of -0.02V, the detectors show a dark current of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.7\times 10^{-5}$ </tex-math></inline-formula> A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and a differential resistance-area of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.5\times 10^{3} \Omega \cdot \text {cm}^{2}$ </tex-math></inline-formula> . The noise equivalent temperature difference and operability of the FPA are 20.7 mK and 99.2% respectively under an integration time of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$400~\mu \text{s}$ </tex-math></inline-formula> , a 300 K background and F/2.0 optics. This high-performance FPA further verifies the feasibility of InAs/GaAsSb T2SL in LWIR detection.