Effect of sulfur incorporation on solution-processed ZTO thin-film transistors

In this research, we investigated the electrical properties of solution-processed sulfur (S)-incorporated zinc-tin-oxide (S-ZTO) thin-film transistors (TFTs). The best device characteristics, which include a threshold voltage of −0.74 V, a sub-threshold swing of 0.67 V/dec, an on/off current ratio of 8.31 × 105, and a mobility of 0.70 cm2/Vs, were observed for 0.06-M S-ZTO TFTs. The device properties of the 0.06-M S-ZTO TFTs were similar to those of ZTO TFTs whereas the illumination stress stabilities and the hysteresis characteristics of the transfer curve for 0.06-M S-ZTO TFTs were better than those for ZTO TFTs. The X-ray diffraction analysis for the S-ZTO thin films also showed that tin (Sn) atoms bonded chemically with S atoms, suggesting that S atoms occupied oxygen sites, which, in turn, the reduced the number of oxygen vacancies. Therefore, the improved stabilities observed in S-ZTO TFTs are attributed to the reduction in the number of oxygen vacancies due to replacement of O by S.