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Time of Flight of Drifting Electrons and Holes in Stabilized a-Se Film

Published online by Cambridge University Press:  01 February 2011

Dong-Gil Lee ,
Ji-Koon Park ,
Jang-Yong Choi ,
Jae-Hyung Kim  and
Sang-Hee Nam
Dong-Gil Lee
Affiliation:
Department of Biomedical Engineering, College of Biomedical Science and Engineering Inje University, Kimhae, Kyungnam, 621-749, Korea
Ji-Koon Park
Affiliation:
Department of Biomedical Engineering, College of Biomedical Science and Engineering Inje University, Kimhae, Kyungnam, 621-749, Korea
Jang-Yong Choi
Affiliation:
Department of Biomedical Engineering, College of Biomedical Science and Engineering Inje University, Kimhae, Kyungnam, 621-749, Korea
Jae-Hyung Kim
Affiliation:
Medical Imaging Research Center Inje University, Kimhae, Kyungnam, 621-749, Korea
Sang-Hee Nam
Affiliation:
Medical Imaging Research Center Inje University, Kimhae, Kyungnam, 621-749, Korea
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Abstract

Large area, flat panel detectors are being investigated for digital radiogrpahy and fluoroscopy. Theses detectors employ an x-ray conversion layer of photoconductor to detect x-rays. The amorphous selenium layer that is currently being studied for its use as an x-ray photoconductor is not pure a-Se but rather a-Se doped with 0.2-0.5% As and 10-30 ppm Cl, also known as stabilized a-Se. The suitability of the stabilized a-Se is largely determined by its charge on generating, transporting and trapping properties.

In this paper, a conventional time-of-flight measurement was carried out to analyze the transport properties of charge carriers. A laser beam with pulse duration of 5 ns and wavelength of 350 nm was illuminated on the surface of the stabilized a-Se with thickness of 400 μm. The photo response signals of the hole and electron were measured at the applied electric field of 10 V/μm as a function of time. The measured transit times of the hole and electron were about 229.17μs and about 8.73μs at 10 V/μm, respectively. The measured mobility indicated a slight dependence with respect to the applied electric field with a range of 4-10 V/μm. The experimental results showed that the measured mobility of the hole and electron was 0.04584 cm2V-1s-1 and 0.00174 cm2V-1s-1 at the electric field of 10 V/μm.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 764: Symposium C – New Applications for Wide-Bandgap Semiconductors , 2003 , C3.53
Copyright
Copyright © Materials Research Society 2003

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