Indium oxide thin film transistors fabricated by low-energetic ion bombardment technique at room temperature

• Published in: Journal of vacuum science & technology. B, Microelectronics and nanometer structures processing, measurement and phenomena Microelectronics and nanometer structures processing, measurement and phenomena, 2010-01, Vol.28 (1), p.211-215
• Main Authors: Chu, A. K., Hong, T. I., Tien, W. C.
• Format: Article
• Language: English
• ISSN: 1071-1023; 2166-2746; 1520-8567; 2166-2754
• DOI: 10.1116/1.3280130

The authors report on In O x transparent thin-film transistor (TTFT) fabricated by low-energetic ion bombardment technique at room temperature. The In O x TTFTs were prepared using a coplanar bottom gate configuration with indium tin oxide (ITO), Si N x , and In O x thin films as the electrode, gate dielectric, and channel, respectively. The quality of the films could be significantly improved by eliminating bombardment of energetic particles created in the discharge processes using a prolonged target-to-substrate distance. The target-to-substrate distance for depositing Si N x was 15 cm , and 18 cm for depositing ITO and In O x . The leakage current density of the 180 nm thick Si N x films under 1.0 MV ∕ cm field strength was less than 1 nA ∕ cm 2 . The C - V measurement of the Al ∕ In O x ∕ p - Si ∕ Al capacitor structure showed that no hysteresis voltage was observed from the high-resistivity In O x films. This indicated that the electrical defects of the 150 nm thick In O x channels could be reduced using the long-throw deposition technique. In addition, the In O x TTFTs were engineered to operate in the enhancement mode with improved carrier mobility by adjusting the oxygen partial pressure during growth. The proposed In O x TTFTs with a 20 μ m channel length presented a saturation mobility of 3.8 cm 2 V − 1 s − 1 , a threshold voltage of 1.7 V , an on/off ratio of 2.3 × 10 6 , and a subthreshold slope of 1.5 V /decade.