Origin of Lower Film Density and Larger Defect Density in Amorphous In-Ga-Zn-O Deposited at High Total Pressure
| Autor: | Hideo Hosono, Jan Dyczewski, Jakub Grochowski, Jakub Kaczmarski, Katsumi Abe, Hidenori Hiramatsu, Hideya Kumomi, Toshio Kamiya, Yuichiro Hanyu |
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| Jazyk: | angličtina |
| Rok vydání: | 2015 |
| Předmět: |
Materials science
Argon Analytical chemistry chemistry.chemical_element Condensed Matter Physics Electronic Optical and Magnetic Materials Amorphous solid Threshold voltage chemistry Sputtering Thin-film transistor Saturation (graph theory) Electrical and Electronic Engineering Thin film Total pressure |
| Zdroj: | J. Disp. Technol.. 11:523-527 |
| Popis: | Amorphous In–Ga–Zn–O (a-IGZO) thin-film transistors (TFTs) are employed in current flat-panel displays. It is known that deposition conditions and post-deposition thermal annealing affect structure and electrical properties of a-IGZO thin films. It was previously reported that total pressure during sputter-deposition deteriorates subthreshold swing, defect density and operation characteristics of a-IGZO TFTs. Here, we provide comprehensive results on effects of total pressure on film density, chemical composition, and TFT characteristics. Rutherford backscattering measurements detected a small amount of argon incorporated in all of the a-IGZO films. We found that increasing the total pressure deteriorated TFT characteristics; i.e., saturation mobility was dropped from 10 to 4 ${\hbox{cm}}^{2}/({\hbox{V}}\cdot {\hbox{s}})$ , subthreshold swing was increased from 0.2 to 0.5 V/dec, and threshold voltage was positive-shifted from 2 to 15 V. It is related to increased oxygen concentration and decreased weight density of the a-IGZO films. Thermal desorption spectra showed that amounts of weakly-bonded oxygen increased as the total pressure increased, which is considered to be related to the TFT deterioration. |
| Databáze: | OpenAIRE |
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