Low Dark Current HgCdTe Long Wavelength Infrared Photodiodes With Bandgap Gradient Multi-Layer Heterojunction
Liqi Zhu, Tianxiang Wu, Zihao Wang, Xi Wang, Xun Li, Songmin Zhou, Zhikai Gan, Chun Lin, Baile Chen
Abstract
In this paper, a novelty bandgap gradient multilayer heterojunction (BGMH) HgCdTe long-wavelength infrared detectors (LWIR) to provide low dark current is designed and prototyped. The fabricated photodetector is comprised of a wide-bandgap gradient p-type cap layer and intrinsic region to optimize the tunneling and surface current, also with a long-wavelength infrared responsed narrow bandgap n-type bottom layer. The BGMH LWIR detector, with a 100% cutoff wavelength of 14 μm, realizes a low dark current density of 5.7×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> under the bias of -0.2V at 78 K. The peak value responsivity of 5.16 A/W and specific detectivity (D*) of 3.83×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> cm·Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> /W are also completed at 10.3 μm. The results suggest that the device performs exceedingly well and achieves beyond the conventional homojunction device.