Spectral crosstalk by radiative recombination in sequential-mode, dual mid-wavelength infrared band HgCdTe detectors
For small pixel, infrared (IR) focal plane arrays (FPAs), Raytheon Vision Systems’ architecture for integrated, dual-band detectors uses the sequential mode of the n-p+-n configuration. There is a single indium bump per pixel, leaving the p+ layer floating, and the operating polarity of the bias selects the spectral sensitivity by reverse-biasing the active p-n junction. Photogenerated minority carriers in the absorber layer of the forward-biased inactive photodiode are lost through recombination. This paper is the first report of a new optical crosstalk mechanism that occurs in sequential-mode, dual-band detectors. In the long-wavelength mode under out-of-band, short-wavelength illumination, radiative recombination yields emission near the bandgap energy of the short-wavelength absorber layer, resulting in a spurious short-wavelength response that appears as spectral crosstalk. We present experimental and device modeling results on the spectral crosstalk in molecular-beam-epitaxy-grown HgCdTe arrays with the cutoff wavelength of both bands in the 4–5-µm range.
Key wordsHgCdTe infrared detector two-color detector crosstalk radiative recombination
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- 3.E.F. Schulte, U.S. patent 5,113,076 (12 May 1992).Google Scholar
- 6.R.D. Rajavel et al., J. Electron. Mater. 26, 476 (1997).Google Scholar
- 8.ISE Integrated Systems Engineering AG, Zurich.Google Scholar
- 9.K. Kosai, J. Electron. Mater. 24, 635 (1995).Google Scholar
- 10.J. Sheng, L. Wang, G.E. Lux, and Y. Gao, J. Electron. Mater. 26, 588 (1997).Google Scholar
- 11.M.B. Reine, A.K. Sood, and T.J. Tredwell, Semiconductors and Semimetals, Vol. 18, eds. R.K. Willardson and A.C. Beer (New York: Academic, 1981), pp. 201–311.Google Scholar
- 14.J.I. Pankove, Optical Processes in Semiconductors (Englewood Cliffs, NJ: Prentice-Hall, 1971), pp. 107–159.Google Scholar