Enhanced Electrical Properties and Stability of GaZnSnO TFTs: The Role of Gallium Composition

This study investigates the influence of Gallium (Ga) doping concentration on the electrical properties and stability of amorphous GaZnSnO (a-GZTO) thin film transistors (TFTs). We fabricated a-GZTO TFTs with 1 wt% and 2 wt% Ga content using RF magnetron sputtering at room temperature and evaluated their performance. The 1 wt% Ga-GZTO TFT exhibited a high field-effect mobility of 25.8 cm²/V·s, demonstrating excellent charge transport characteristics. Both 1 wt% and 2 wt% Ga-GZTO TFTs showed good stability under temperature stress (RT to 60 °C), with the 2 wt% device showing a slightly reduced threshold voltage shift. Density of States (DOS) analysis revealed subtle differences in defect characteristics. Specifically, increasing Ga content from 1 wt% to 2 wt% resulted in a decrease in mobility (from 25.8 to 21.2 cm²/V·s) and a reduction in oxygen vacancy concentration, as confirmed by X-ray Photoelectron Spectroscopy (XPS) analysis. These results indicate that controlling the Gallium doping concentration in a-GZTO TFTs allows for a balance between high mobility and good stability, making them promising candidates for next-generation display applications.