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23 April 2008 "XBn" barrier photodetectors for high sensitivity and high operating temperature infrared sensors
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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.
© (2008) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Philip Klipstein ""XBn" barrier photodetectors for high sensitivity and high operating temperature infrared sensors", Proc. SPIE 6940, Infrared Technology and Applications XXXIV, 69402U (23 April 2008); https://doi.org/10.1117/12.778848
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