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Proceedings Paper

Fabrication of the GaAs based terahertz photoconductors and the photometer for Tera-GATE
Author(s): Kentaroh Watanabe; Kyouhei Yamashita; Hirokazu Kataza; Takafumi Kamizuka; Takehiko Wada; Moriaki Wakaki; Osamu Abe; Hiroshi Murakami
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Paper Abstract

The present status of the development of an extrinsic photoconductor based on a high-purity GaAs is reported. This photoconductor utilizing the shallow donor levels in GaAs and is highly sensitive for incident terahertz photons in the wavelength range 150 to 300 micron. The n-type GaAs crystal has been growth by liquid phase epitaxial (LPE) method, which is suitable to obtain thick and high-purity GaAs. The impurity concentration in GaAs layer has been decreased to the order of 1013 atoms/cm-3. By doping the donors lightly in the LPE growth process, C/Si, (background doped) Se and Te doped GaAs layers has been fabricated. The GaAs photoconductors using these crystals are sensitive in longer wavelength region than Ge:Ga photoconductors used in the past far-infrared astronomical observations. The most sensitive detector is obtained with C or Si background doped GaAs, of which NEP is reached to 3×10-16 W/Hz0.5 at the temperature of 1.5 K, at 290 micron, the peak of its responsivity spectrum. A balloon-borne telescope utilizing our GaAs photoconductors, Tera-GATE (THz observation with GaAs photoconductors and a balloon-borne Telescope) is now under development. The Tera-GATE is a 69 cm diameter telescope. On its focal plane, a photoconductor array with Winston cone has 2-mm entrance aperture and leads the incident photons to a cavity where 0.5-mm size photoconductor is installed. Measured optical efficiency of the cone/cavity system is in an acceptable range ~40 percent.

Paper Details

Date Published: 21 July 2008
PDF: 10 pages
Proc. SPIE 7020, Millimeter and Submillimeter Detectors and Instrumentation for Astronomy IV, 702020 (21 July 2008); doi: 10.1117/12.789143
Show Author Affiliations
Kentaroh Watanabe, Japan Aerospace Exploration Agency (Japan)
Kyouhei Yamashita, Tokai Univ. (Japan)
Hirokazu Kataza, Japan Aerospace Exploration Agency (Japan)
Takafumi Kamizuka, The Univ. of Tokyo (Japan)
Takehiko Wada, Japan Aerospace Exploration Agency (Japan)
Moriaki Wakaki, Tokai Univ. (Japan)
Osamu Abe, JASCO Opt Co., LTD. (Japan)
Hiroshi Murakami, Japan Aerospace Exploration Agency (Japan)

Published in SPIE Proceedings Vol. 7020:
Millimeter and Submillimeter Detectors and Instrumentation for Astronomy IV
William D. Duncan; Wayne S. Holland; Stafford Withington; Jonas Zmuidzinas, Editor(s)

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