Dark current mechanisms in HgCdTe photodiodes

Y. K. Su, S. J. Chang, F. S. Juang, C. D. Chiang, Y. T. Cherng, S. M. Chang

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1 Citation (Scopus)


Experimental and theoretical results are presented for current-voltage and dynamic resistance-voltage characteristics of Hg1-xCdxTe ion-implanted p-n junction photodiodes with x≈0.22. By measuring the temperature dependence of the dc characteristics in the temperature range 25-140 K, the dark current mechanisms are studied At high temperature (>90 K) and in low reverse bias region, the diffusion current dominates. On the other hand at medium temperature (40-80 K) and medium reverse bias (<-0.15 volt), trap-assisted tunneling plays an important role. At low temperature (<40 K) and in the medium reverse bias region (<-0.15 volt), band-to-band tunneling is the key leakage current source. However, when the temperature is further lowed down to 25 K and the applied reverse bias is very small (-0.15∼0 volt), the band-to-band tunneling current will be ruled out and the trap-assisted tunneling mechanism dominates again. We have measured l/f noise in HgCdTe photodiode as a function of temperature, diode bias, dark current. The dependence of 1/f noise on dark current was measured over a wide temperature range on devices. The temperature dependence of the 1/f noise was found to be the same as the temperature dependence of the surface generation and leakage currents. We obtained the maximum specific detectivity (D*) value and the maximum signal-to-noise ratio are about 3.51 × 1010 cm·Hz1/2/W and 5096, respectively.

Original languageEnglish
Pages (from-to)256-266
Number of pages11
JournalProceedings of SPIE - The International Society for Optical Engineering
Publication statusPublished - 1998
EventOptoelectronic Materials and Devices - Taipei, Taiwan
Duration: 1998 Jul 91998 Jul 11

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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