DocumentCode :
1282273
Title :
Simple Analytical Model of On Operation of Amorphous In–Ga–Zn–O Thin-Film Transistors
Author :
Abe, Kiyohiko ; Kaji, Naoki ; Kumomi, Hideya ; Nomura, Keigo ; Kamiya, Toshio ; Hirano, Masahiro ; Hosono, Hideo
Author_Institution :
Canon Inc., Tokyo, Japan
Volume :
58
Issue :
10
fYear :
2011
Firstpage :
3463
Lastpage :
3471
Abstract :
The on operation of an amorphous In-Ga-Zn-O thin-film transistor (a-IGZO TFT) was studied employing a gated-four-probe (GFP) structure TFT to build a simple analytical model based on bias-dependent field-effect mobility (μFE). The electrical characteristics of the a-IGZO GFP TFT revealed that the contact resistances were negligible compared with the channel resistance. The bias-dependent μFE was derived from the transfer characteristics at low drain voltages (VD) , and approximately represented by a power function of the bias voltage, like that for hydrogenated amorphous Si (a-Si:H) TFTs. The mobility model reproduced both the current-voltage characteristics and the potential distribution in the channel, including the high VD region. Si TFTs exhibit non-negligible variation of drain current (ID) in the saturation region and their models require extra parameters to describe it. In contrast, the a-IGZO TFTs exhibit flat ID-VD characteristics in the saturation region, and their model does not require an extra parameter. Due to these features, the model of the a-IGZO TFTs is simpler than those of a-Si:H TFTs. The temperature dependence of the TFT characteristics indicated that the bias dependence of μFE cannot be explained just by the exponential subgap traps. The dependence should be understood by introducing the carrier-density dependent mobility of a-IGZO films.
Keywords :
carrier density; contact resistance; gallium; indium; oxygen; thin film transistors; zinc; In-Ga-Zn-O; amorphous thin-film transistors; bias-dependent field-effect mobility; carrier-density dependent mobility; contact resistances; current-voltage characteristics; exponential subgap traps; gated-four-probe structure; hydrogenated amorphous; power function; saturation region; transfer characteristics; Analytical models; Electric potential; Electrodes; Integrated circuit modeling; Logic gates; Silicon; Thin film transistors; Amorphous In–Ga–Zn–O (a-IGZO); amorphous oxide semiconductor (AOS); gated-four-probe (GFP) structure; on operation model; thin-film transistor (TFT);
fLanguage :
English
Journal_Title :
Electron Devices, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9383
Type :
jour
DOI :
10.1109/TED.2011.2160981
Filename :
5961613
Link To Document :
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