Minority carrier lifetime in abrupt MBE-grown HgCdTe heterostructures

Richard Sewell; John M. Dell; Charles A. Musca; Lorenzo Faraone

doi:10.1117/12.473283

5 December 2002 Minority carrier lifetime in abrupt MBE grown HgCdTe heterostructures

Richard Sewell, John M. Dell, Charles A. Musca, Lorenzo Faraone

Proceedings Volume 4795, Materials for Infrared Detectors II; (2002) https://doi.org/10.1117/12.473283
Event: International Symposium on Optical Science and Technology, 2002, Seattle, WA, United States

Abstract

Steady state minority carrier lifetime has been investigated in heterostructure HgCdTe devices fabricated on Molecular Beam Epitaxy (MBE) grown material. Wider band gap Hg_(1-x)Cd_(x)Te x = 0.44 was MBE grown on narrower gap Hg_(1-x)Cd_(x)Te x = 0.32 material to create an abrupt interface. Both layers were unintentionally doped n-type as determined by Hall measurements, which show two distinct electron species corresponding to the two HgCdTe layers. Steady state lifetime as a function of temperature over the range 80K to 300K was extracted from responsivity and noise measurements performed on variable area photoconductor structures fabricated on the sample. At 80K, the photoconductors exhibit a specific detectivity at 1kHz of 4.5 x 10¹¹ cmHz^-1W^-1. For each measurement temperature, the steady state excess carrier lifetime determined experimentally was compared to the theoretical bulk lifetime for material with x = 0.32 and effective n-type doping density of 3.7 x 10¹⁴cm^-3. For temperatures below 180K, measured lifetime is in agreement with bulk lifetime of ~12μs, however, for higher temperatures there is evidence of an additional mechanism which reduces the apparent lifetime in the material. It is concluded that for temperatures above 180K, there is significant thermally induced promotion of photogenerated carriers from the narrow bandgap material into the wide bandgap material, leading to a reduction in the responsivity of the detector due to the relatively high doping of the wide bandgap layer.

Citation Download Citation

Richard Sewell, John M. Dell, Charles A. Musca, and Lorenzo Faraone "Minority carrier lifetime in abrupt MBE grown HgCdTe heterostructures", Proc. SPIE 4795, Materials for Infrared Detectors II, (5 December 2002); https://doi.org/10.1117/12.473283

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