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The Effect of Annealing Ambient on the Characteristics of an Indium-Gallium-Zinc Oxide Thin Film Transistor

Title
The Effect of Annealing Ambient on the Characteristics of an Indium-Gallium-Zinc Oxide Thin Film Transistor
Author
전형탁
Keywords
Oxide Semiconductor; IGZO; Thin Film Transistor; Annealing Effect
Issue Date
2011-07
Publisher
AMER SCIENTIFIC PUBLISHERS, 26650 THE OLD RD, STE 208, VALENCIA, CA 91381-0751 USA
Citation
JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY, VOL.11, NO.7, JUL 2011, pp. 6029-6033
Abstract
In this study, the effects of different annealing conditions (air, O(2), N(2), vacuum) on the chemical and electrical characteristics of amorphous indium gallium zinc oxide (a-IGZO) thin film transistors (TFT) were investigated. The contact resistance and interface properties between the IGZO film and the gate dielectric improved after an annealing treatment. However, the chemical bonds in the IGZO bulk changed under various annealing atmospheres, which, in turn, altered the characteristics of the TFTs. The TFTs annealed in vacuum and N(2) ambients exhibited undesired switching properties due to the high carrier concentration (> 10(17) cm(-3)) of the IGZO active layer. In contrast, the IGZO TFTs annealed in air and oxygen ambients displayed clear transfer characteristics due to an adequately adjusted carrier concentration in the operating range of the TFT. Such an optimal carrier concentration arose through the stabilization of unstable chemical bonds in the IGZO film. With regard to device performance, the TFTs annealed in O(2) and air exhibited saturation mobility values of 8.29 and 7.54 cm(2)/Vs, on-off ratios of 7.34 x 10(8) and 3.95 x 10(8), and subthreshold swing (SS) values of 0.23 and 0.19 V/decade, respectively. Therefore, proper annealing ambients contributed to internal modifications in the IGZO structure and led to an enhancement in the oxidation state of the metal. As a result, defects such as oxygen vacancies were eliminated. Oxygen annealing is thus effective for controlling the carrier concentration of the active layer, decreasing electron traps, and enhancing TFT performance.
URI
http://www.ingentaconnect.com/content/asp/jnn/2011/00000011/00000007/art00077
ISSN
1533-4880
DOI
10.1166/jnn.2011.4360
Appears in Collections:
COLLEGE OF ENGINEERING[S](공과대학) > MATERIALS SCIENCE AND ENGINEERING(신소재공학부) > Articles
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