Jpn. J. Appl. Phys. 44 (2005) pp. 6742-6746  |Previous Article| |Next Article|  |Table of Contents|
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Effect of He Plasma Treatment on the Rectification Properties of Al/CdTe Schottky Contacts

Hiroyuki Toyama, Masaaki Yamazato, Akira Higa, Takehiro Maehama, Ryoichi Ohno1 and Minoru Toguchi

Faculty of Engineering, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa 903-0213, Japan
1Acrorad Co., Ltd., 13-23 Suzaki, Uruma, Okinawa 904-2234, Japan

(Received December 16, 2004; revised May 10, 2005; accepted June 2, 2005; published September 8, 2005)

We investigated the effect of He plasma treatment on the surface composition of CdTe and the electrical properties of Al/CdTe Schottky contacts. The composition of the initial CdTe surface is Te-rich due to Br-methanol etching. When Al Schottky contacts are formed on the CdTe surfaces with the Te-rich layer, the barrier height is low and the rectification property is not good. In this paper, we propose the He plasma treatment method to remove the Te-rich layer. From X-ray photoelectron spectroscopy measurement, it was found that the plasma treatment can remove the Te-rich layer. The rectification property of the Al Schottky contacts on the plasma-treated surfaces is improved, and their barrier heights are estimated to be about 0.65 eV. In γ-ray spectrometry, a high-energy resolution of 1.6 keV full width at half maximum at 59.5 keV was obtained from the plasma-treated Al/CdTe/Pt detector. The results indicate that the plasma treatment of CdTe surfaces significantly improves the energy resolution of Schottky-type Al/CdTe/Pt radiation detectors.

URL: http://jjap.jsap.jp/link?JJAP/44/6742/
DOI: 10.1143/JJAP.44.6742
KEYWORDS:CdTe, He plasma treatment, Schottky barrier, X-ray and γ-ray detector


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