We generated solution-processed thin film transistor (TFTs) using gallium tin zinc oxide (GTZO, Ga-Sn-Zn-O) layers as the channel that exhibit improved bias-stress stability during device operation under ambient conditions. The cause of the bias-stress stability was investigated through comparisons with zinc tin oxide (ZTO, Zn-Sn-O)-based TFTs, which suffer red from bias stress instability. Based on in-depth analysis of the electrical characteristics and chemical structure of both GTZO and ZTO layers, it was discovered that the GTZO layers had a significantly lower oxygen vacancy concentration than did the ZTO layer, which influenced the electrical performance of the GTZO transistors as well as their bias-stress stability. When 5 mol% gallium was added, a bias stress-stable transistor was obtained, exhibiting typical semiconductor behavior with a field-effect mobility of 1.2 cm2 V- 1 s - 1, on/off ratio of 106, off-current of 1 × 10 - 10 A, and threshold voltage of 19.6 V. Further doping of Ga deteriorated the device performance, which was found to be associated with decreased carrier concentration and segregation of an insulating secondary phase.
Bibliographical noteFunding Information:
This work was supported by the Mid-Career Researcher Program through an NRF grant funded by the MEST (No. 2009-0086302 ). It was also partly supported by the Second Stage of the Brain Korea 21 Project . In addition, we acknowledge the Pohang Accelerator Laboratory (PAL) for conducting the GI-XRD measurements.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Metals and Alloys
- Materials Chemistry