Ghosh, S.; Sun, G.; Morgan, T.A.; Forcherio, G.T.; Cheng, H.-H.; Chang, G.-E. Dark Current Analysis on GeSn p-i-n Photodetectors. Sensors2023, 23, 7531.
Ghosh, S.; Sun, G.; Morgan, T.A.; Forcherio, G.T.; Cheng, H.-H.; Chang, G.-E. Dark Current Analysis on GeSn p-i-n Photodetectors. Sensors 2023, 23, 7531.
Ghosh, S.; Sun, G.; Morgan, T.A.; Forcherio, G.T.; Cheng, H.-H.; Chang, G.-E. Dark Current Analysis on GeSn p-i-n Photodetectors. Sensors2023, 23, 7531.
Ghosh, S.; Sun, G.; Morgan, T.A.; Forcherio, G.T.; Cheng, H.-H.; Chang, G.-E. Dark Current Analysis on GeSn p-i-n Photodetectors. Sensors 2023, 23, 7531.
Abstract
Group IV alloys of GeSn have been extensively investigated as a competing material alternative in short-wave to mid-infrared photodetectors (PDs). The relatively large defect densities present in GeSn alloys are the major challenge in developing practical devices, owing to the low-temperature growth and lattice mismatch with Si or Ge substrates. In this paper, we comprehensively analyze the impact of defects on the performance of GeSn p-i-n homojunction PDs. We first present our theoretical models to calculate various contributing components of the dark current including minority carrier diffusion in p- and n-regions, carrier generation-recombination in the active intrinsic region, as well as the tunneling effect. We then analyze the effect of defect density in the GeSn active region on carrier mobilities, scattering times and the dark current. A higher defect density increases the dark current, resulting in reduction in detectivity of GeSn p-i-n PDs. In addition, at low Sn concentrations, defect-related dark current density is dominant, while the generation dark current becomes dominant at a higher Sn content. These results point to the importance of minimizing defect densities in the GeSn material growth and device processing, particularly for higher Sn compositions necessary to expand the cutoff wavelength to mid- and long-wave infrared regime. The study provides more of realistic expectations and guidelines for evaluating GeSn p-i-n PDs as a competitor to the III-V and II-VI-based infrared PDs currently on the commercial market.
Keywords
GeSn alloys; Defects; Dark current; Detectivity; Sustainability
Subject
Physical Sciences, Optics and Photonics
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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