Viable strategy to minimize trap states of patterned oxide thin films for both exceptional electrical performance and uniformity in sol–gel processed transistors

A sustainable water etchant-based photopatterning method is proposed to achieve simultaneous oxide film patterning and remarkably minimize trap states of dielectric and semiconductor oxide films. By exquisitely controlling each processing parameter, well-defined aluminum oxide (AlOx) dielectric and indium oxide (InOx) semiconductor patterns are formed, despite using acid-free pure water etchant. The water etchant not only dissolves the nonultraviolet-irradiated regions but also promotes an effective hydrolysis reaction of irradiated regions, thereby forming low-defect oxide patterns. As a result, frequency-stable AlOx capacitors with low leakage current and high-performance bias-stable InOx TFTs with low activation energy are fabricated. In particular, photopatterned enhancement-mode InOx TFTs exhibit remarkably improved electrical properties, stability, and uniformity—15-fold higher saturation mobility and remarkably low coefficient of variation of 12.04 cm2 V−1 s−1 and 25.26%, respectively— compared with nonpatterned TFTs. With the proposed method, 3-V operating high-performance InOx/AlOx TFTs are successfully fabricated at a low processing temperature of 250 °C.