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Proceedings Paper

Hg1-xCdxTe(112) nucleation on silicon composite substrates
Author(s): Paul Boieriu; G. Brill; Y. P. Chen; Silviu Velicu; Nibir K. Dhar
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Paper Abstract

The epitaxial growth of Hg1-xCdxTe in the composition range 0.40 < x < 0.17 has been carried out on 3-inch CdTe/Si substrates mounted on indium-free molybdenum substrate holders. Because this mounting configuration prevents the effective use of a direct thermocouple contact to control the sample temperature, and because a dramatic change in the surface emissivity of the sample occurs during the onset of HgCdTe nucleation, an alternative method for controlling the surface temperature is developed. We utilize reflection high-energy electron diffraction (RHEED) and a thermocouple ramping sequence to maintain a constant HgCdTe surface temperature. Due to the narrowness of the HgCdTe growth window, small variations in the surface temperature produce a slight but observable change in the RHEED pattern. Through careful observation of the RHEED images, an optimized thermocouple ramping process is obtained such that the RHEED pattern remained constant from the onset of HgCdTe nucleation. Structural and electrical characterization of these samples demonstrate the usefulness of the temperature ramping methodology. For middle wavelength IR (MWIR) material, mobility measurements made on several n-type samples at 77 K range give values in the 2 X 104 - 4 X 104 cm2/Vsec range with doping levels in the low 1014 cm-3. Additionally, preliminary lifetime measurements made on one MWIR sample gives 2.8 microsecond(s) ec. For long wavelength IR material, mobility measurements made on several n-type samples at 77 K give values in the 3 X 105 to 5 X 105 cm2/Vsec range with doping levels in the mid 1015 cm-3. Electrical, structural and defect characterization along with device results are presented with a focus on the optimization of the thermocouple ramping process. In addition, the efficacy of Si-based composite substrates for the technological advancement of large format IR focal plane arrays will be discussed.

Paper Details

Date Published: 12 November 2001
PDF: 11 pages
Proc. SPIE 4454, Materials for Infrared Detectors, (12 November 2001); doi: 10.1117/12.448190
Show Author Affiliations
Paul Boieriu, EPIR Ltd. (United States)
G. Brill, EPIR Ltd. (United States)
Y. P. Chen, EPIR Ltd. (United States)
Silviu Velicu, Smart Pixel, Inc. (United States)
Nibir K. Dhar, Army Research Lab. (United States)

Published in SPIE Proceedings Vol. 4454:
Materials for Infrared Detectors
Randolph E. Longshore, Editor(s)

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