Effect of Mg addition on the electrical characteristics of solution-processed amorphous Mg-Zn-Sn-O thin film transistors

Solution-processed thin film transistors (TFTs) using a magnesium zinc tin oxide (MZTO, Ma-Zn-Sn-O) channel layer were fabricated and bias-stress stability during device operation was evaluated. The cause of the bias-stress instability was investigated through comparison with zinc tin oxide (ZTO, Zn-Sn-O) TFTs. The MZTO layers had a significantly lower oxygen vacancy concentration than the ZTO layer, which affected the electrical characteristics as well as bias-stress stability of MZTO TFTs. When 2 mol% Mg was added, a more stable transistor was attained, showing a typical semiconductor behavior with a saturation mobility of 0.27 cm2/V·s, on/off ratio of 3.3 × 106, off-current of 5.3 × 10− 12A, and threshold voltage of 5.4 V.