Probing the Dark Current of Multi-Layer Heterojunction HgCdTe Long-Wavelength and Very-Long-Wavelength Infrared Photodiodes

This paper characterizes the dark current development of p-on-n type HgCdTe multi-layer heterojunction long wavelength infrared (LWIR) and very long wavelength infrared (VLWIR) photodiodes. Four devices that operate at different wavelengths are fabricated by employing a multi-layer structure. The results demonstrate the favorable dark current which is close to the “Rule 07” limitation is obtained with a 50% cutoff wavelength of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$16.6~\mu $ </tex-math></inline-formula>m. Besides, the influence mechanisms on the device are extracted by analyzing the temperature-dependent dark current from 40 K to 130 K. The results suggest that the proposed devices perform comparable to those of conventional double-layer heterojunction devices. Furthermore, it can be noted that by precisely controlling the composition distribution and depletion region positions as well as improving the process, we can further achieve superior LWIR and VLWIR devices.