High performance HgCdTe photodetector desings via dark current suppression

Özer, Yiğit
This thesis work covers the numerical analysis and design of infrared photon detectors with a focus of HgCdTe based devices. An in-house numerical tool is utilized for the design and characterization process, where the Poisson, current and continuity equations are solved numerically with the high precision in electrical and optical properties. A high operating temperature alternative substrate mid-wave HgCdTe detector is designed benefiting from the generation-recombination dark current suppression. The advancement in the operating temperature is nearly 40 K (from ~85 K to ~125 K) for the designed device structure, which leads to diffusion limited dark current even for a very low carrier lifetimes (τSRH = 200 ns). The performance enhancement is achieved by the utilization of high Cd composition material at the depletion region targeting lower SRH recombination rates. The sensitivity of the designed structure to the fabrication errors is analyzed in terms of doping, composition and layer thickness. Moreover, a design methodology is introduced so that the inserted wide bandgap layer does not create valence band discontinuity that might lead to a noticeable decrease in quantum efficiency. In addition, a similar method is applied to SWIR window and performance of HgCdTe SWIR detectors has been shown to increase as well. The designed SWIR detector reached state-of-art sensors in terms of dark current density while benefiting from the reduced cost of alternative substrate detectors. With this enhancement, the designed HgCdTe sensors are capable of sensing based on solely nightglow radiation.
Citation Formats
Y. Özer, “High performance HgCdTe photodetector desings via dark current suppression,” M.S. - Master of Science, Middle East Technical University, 2018.