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Poly-SiGe TFTs Fabricated by Low Temperature Chemical Vapor Deposition at 450°C

Published online by Cambridge University Press:  15 March 2011

Kousaku Shimizu
Affiliation:
Imaging Science and Engineering Laboratory, Tokyo Institute of Technology, 4259 Nagatsutacho, Midoriku, Yokohama 226-8503, Japan
Jianjun Zhang
Affiliation:
Imaging Science and Engineering Laboratory, Tokyo Institute of Technology, 4259 Nagatsutacho, Midoriku, Yokohama 226-8503, Japan
Jeong-woo Lee
Affiliation:
Imaging Science and Engineering Laboratory, Tokyo Institute of Technology, 4259 Nagatsutacho, Midoriku, Yokohama 226-8503, Japan
Jun-ichi Hanna
Affiliation:
Imaging Science and Engineering Laboratory, Tokyo Institute of Technology, 4259 Nagatsutacho, Midoriku, Yokohama 226-8503, Japan
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Abstract

Low temperature growth of poly-SiGe has been investigated by reactive thermal chemical vapor deposition technique, which is a newly developed technique for preparing polycrystalline materials with using redox reactions in a set of source materials, Si2H6 and GeF4.. In order to prepare high uniformity and reproducibility of Si-rich poly-SiGe, total pressure, gas flow ratio, and residence time are optimized at 450°C of substrate temperature. Through optimizing the conditions, poly-Si1−xGex (x<0.04) films have been prepared in the reproducibility more than 90% and uniformity more than 88%. Bottom gate type of n-channel thin film transistors has been fabricated in various grain size of poly-Si1−xGex on SiO2 (100nm)/Si substrates. 5-36 cm2/Vs of field effect mobility of thin film transistors (L/W = 50μm/50μm) have been achieved after hydrogenation, whose threshold voltage is around 2±0.5V, and on/off ratio is more than 104.

Type
Research Article
Copyright
Copyright © Materials Research Society 2002

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