Localization effect of a current-path in amorphous In-Ga-Zn-O thin film transistors with a highly doped buried-layer

Title
Localization effect of a current-path in amorphous In-Ga-Zn-O thin film transistors with a highly doped buried-layer
Authors
정유진전용우전윤수김대환이상렬
Keywords
Density of state; Buried channel structure; Zn-rich layer; Thin Film Transistor; Ga-doped Zinc Oxide; Interface; Transmission Electron Microscopy
Issue Date
2011-04
Publisher
Thin solid films
Citation
VOL 519, NO 13, 4347-4350
Abstract
The highly-doped buried layer (carrier concentration of ~1019 cm−3) in an amorphous indium–gallium–zinc oxide (a-IGZO) channel layer of thin film transistor (TFT) led to dramatic improvements in the performance and prolonged bias-stability without any high temperature treatment. These improvements are associated with the enhancement in density-of-states and carrier transport. The channel layer is composed of Ga-doped ZnO (GZO) and a-IGZO layers. Measurements performed on GZO-buried a-IGZO (GB-IGZO) TFTs indicate enhanced n-channel active layer characteristics, such as Vth, μFE, Ioff, Ion/off ratio and S.S, which were enhanced to 1.2 V, 10.04 ㎠/V·s, ~10−13A, ~107 and 0.93 V/decade, respectively. From the result of simulation, a current path was well defined through the surface of oxide active layer especially in GB-IGZO TFT case because the highly-doped buried layer plays the critical role of supplying sufficient negative charge density to compensate the amount of positive charge induced by the increasing gate voltage. The mechanismunderlying the high performance and good stability is found to be the localization effect of a current path due to a highlydoped buried layer, which also effectively screens the oxide bulk and/or back interface trap-induced bias temperature instability.
URI
http://pubs.kist.re.kr/handle/201004/40628
ISSN
0040-6090
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KIST Publication > Article
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