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Proceedings Paper

"XBn" barrier photodetectors for high sensitivity and high operating temperature infrared sensors
Author(s): Philip Klipstein
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Paper Abstract

A barrier photodetector is a device in which the light is absorbed in a narrow bandgap semiconductor layer whose bands remain essentially flat or accumulated at the operating bias so that all carrier depletion is excluded. In a conventional photodiode below a threshold temperature T0, typically 130-150K for MWIR devices, the dark current is due to Generation-Recombination (G-R) centres in the depletion layer. In a barrier detector, the absence of depletion in the narrow bandgap semiconductor ensures that the G-R contribution to the dark current is negligible. The dark current in the barrier detector is thus dominated by the diffusion component, both above and below T0. Therefore, at a given temperature below T0, a barrier detector will exhibit a lower dark current than a conventional photodiode with the same cut-off wavelength. Alternatively, for a given dark current, a barrier detector will operate at a higher temperature than a conventional photodiode, provided that this temperature is below T0. Device architectures are presented for barrier detectors with photon absorbing layers based on InAs1-xSbx alloys and type-II InAs/GaSb superlattices (T2SL). The thermionic and tunneling components of the dark current are analyzed and shown to be negligible for typical device parameters. An operating temperature of ~150K is estimated for a MWIR barrier detector with f/3 optics and a cut-off wavelength of 4.2μ.

Paper Details

Date Published: 23 April 2008
PDF: 12 pages
Proc. SPIE 6940, Infrared Technology and Applications XXXIV, 69402U (23 April 2008); doi: 10.1117/12.778848
Show Author Affiliations
Philip Klipstein, Semiconductor Devices (Israel)


Published in SPIE Proceedings Vol. 6940:
Infrared Technology and Applications XXXIV
Bjørn F. Andresen; Gabor F. Fulop; Paul R. Norton, Editor(s)

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