Electrical Properties of Yttrium–Indium–Zinc-Oxide Thin Film Transistors Fabricated Using the Sol–Gel Process and Various Yttrium Compositions

This study was the first to investigate the fabrication of yttrium–indium–zinc-oxide (YIZO) thin film transistors (TFTs) using the sol–gel process. YIZO thin films were made using various yttrium (Y) compositions from 10 to 20%. Thermogravimetry and differential scanning calorimetry (TG–DSC) data from the 15% Y sample revealed that the YIZO thin films crystallized above the temperature of 535 °C, much hotter than that of indium–gallium–zinc-oxide (IGZO) thin films. The best performance of YIZO TFTs was observed with a 15% ratio of Y to Zn: this yielded a saturation mobility of 1.12 cm 2 V -1 s -1 , an on/off ratio of 4.61×10 5 , a threshold voltage of 0.54 V, and a subthreshold swing of 1.03 V/decade. This study also assessed the post-annealing temperature dependence of YIZO TFTs. The findings demonstrated the possibility of using Y to replace gallium (Ga), which has been used in previously reported solution-processed IGZO TFTs.