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Proceedings Paper

Minority carrier lifetime in abrupt MBE-grown HgCdTe heterostructures
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Paper 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.

Paper Details

Date Published: 5 December 2002
PDF: 8 pages
Proc. SPIE 4795, Materials for Infrared Detectors II, (5 December 2002); doi: 10.1117/12.473283
Show Author Affiliations
Richard Sewell, Univ. of Western Australia (Australia)
John M. Dell, Univ. of Western Australia (Australia)
Charles A. Musca, Univ. of Western Australia (Australia)
Lorenzo Faraone, Univ. of Western Australia (Australia)

Published in SPIE Proceedings Vol. 4795:
Materials for Infrared Detectors II
Randolph E. Longshore; Sivalingam Sivananthan, Editor(s)

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