Effects of Ta incorporation in Y2O3 gate dielectric of InGaZnO thin-film transistor

• Published in: Applied physics letters 2016-10, Vol.109 (16)
• Main Authors: Song, J. Q., Qian, L. X., Lai, P. T.
• Format: Article
• Language: English
• Subjects: Applied physics; Atomic force microscopy; Dielectrics; Hygroscopicity; Incorporation; Interface roughness; Noise measurement; Saturation; Silicon; Thin films; Threshold voltage; Transistors; Yttrium oxide
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4965849

The effects of Ta incorporation in Y2O3 gate dielectric on the electrical characteristics of InGaZnO thin-film transistor are investigated. With an appropriate Ta content in the Y2O3 gate dielectric, the saturation mobility of the thin-film transistor can be significantly increased, about three times that of the control sample with Y2O3 gate dielectric. Accordingly, the sample with a Ta/Ta+Y ratio of 68.6% presents a high saturation mobility of 33.5 cm2 V−1 s−1, low threshold voltage of 2.0 V, large on/off current ratio of 2.8 × 107, and suppressed hysteresis. This can be attributed to the fact that the Ta incorporation can suppress the hygroscopicity of Y2O3 and thus reduces the Y2O3/InGaZnO interface roughness and also the traps at/near the interface, as supported by atomic force microscopy and low-frequency noise measurement, respectively. However, excessive Ta incorporation in the Y2O3 gate dielectric leads to degradation in device performance because Ta-related defects are generated.