Structural relaxation in amorphous oxide semiconductor, a-In-Ga-Zn-O
- Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)
- Frontier Research Center, Tokyo Institute of Technology, 4259, Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)
Amorphous In-Ga-Zn-O (a-IGZO) is expected as a backplane transistor material to drive next-generation flat-panel and flexible displays. It has been elucidated that thermal annealing even at low temperatures <200 deg. C reduces deep subgap defects and those at {>=}300 deg. C further improve device characteristics, stability, and uniformity. These temperatures are much lower than the reported crystallization temperature (T{sub X}{approx} 600 deg. C). In this work, we investigate effects of thermal annealing on the structural and optical properties of a-IGZO thin films. We performed classical molecular dynamics simulation (CMD) and optical interference analyses including spectroscopic ellipsometry (SE). CMD reproduced the x-ray diffraction pattern of a-IGZO and exhibited a glass transition. Experimentally, it was found that T{sub X} depends largely on deposition methods and conditions, probably due to different chemical compositions. Sputter-deposited a-IGZO films exhibited onset T{sub X}{approx} 600 deg. C and crystalline volume fraction X{sub C} increased linearly from 600 deg. C. 1.2% of film densification occurred even at 600 deg. C due to crystallization. High-temperature in situ SE measurements did not detect a symptom of a glass transition temperature (T{sub g}) presumably because the T{sub X} is close to T{sub g} similar to the case of amorphous metals.
- OSTI ID:
- 22036842
- Journal Information:
- Journal of Applied Physics, Vol. 111, Issue 7; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
36 MATERIALS SCIENCE
ANNEALING
CRYSTALLIZATION
ELLIPSOMETRY
ENERGY GAP
GALLIUM COMPOUNDS
GLASS
INDIUM COMPOUNDS
MOLECULAR DYNAMICS METHOD
REFLECTIVITY
SEMICONDUCTOR MATERIALS
THIN FILMS
TRANSITION TEMPERATURE
X-RAY DIFFRACTION
ZINC OXIDES