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Proceedings Paper

Activation of arsenic in epitaxial Hg1–xCdxTe (MCT)
Author(s): P. Capper; D. Shaw
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Paper Abstract

This paper reviews arsenic (As) dopant activation processes in the various forms of epitaxial MCT. Extrinsic doping of MCT is an important part of MCT technology and As doping is preferred as it is a shallow acceptor dopant with low diffusivity and 100% activation can be achieved under the correct growth and/or post-growth annealing conditions. It is, however, amphoteric so that under Te-rich growth conditions it can be incorporated as a donor (AsHg) and under metal-rich conditions as an acceptor (As'Te). For As concentrations up to ~ 2 × 1018 cm-3 the amphoteric model provides a satisfactory basis for explaining the behavior on annealing layers at temperatures above ~ 250 oC. Under Te-rich conditions in LPE- and MBE-grown layers can be either compensated n-type or the As can be inactive. The quantitative model of Schaake is used to obtain an expression for the activation anneal time in terms of As concentration, layer thickness, composition and temperature. Layers grown by MOVPE can show up to 100% acceptor activation if the stoichiometric conditions during the CdTe growth cycle of the interdiffused multilayer (IMP) process are maintained as metal-rich. In as-grown MBE layers the evidence indicates that As is incorporated in the form of tetramers that can dissociate at higher temperatures. The issue of establishing whether layers are electrically intrinsic at the annealing temperatures used to activate the As acceptor in LPE and MBE layers is also discussed.

Paper Details

Date Published: 7 September 2006
PDF: 12 pages
Proc. SPIE 6294, Infrared and Photoelectronic Imagers and Detector Devices II, 62940M (7 September 2006); doi: 10.1117/12.680250
Show Author Affiliations
P. Capper, Selex Sensors and Airborne Systems Infra-Red Ltd. (United Kingdom)
D. Shaw, Hull Univ. (United Kingdom)

Published in SPIE Proceedings Vol. 6294:
Infrared and Photoelectronic Imagers and Detector Devices II
Randolph E. Longshore; Ashok Sood, Editor(s)

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