Significant Performance Improvement of Oxide Thin-Film Transistors by a Self-Assembled Monolayer Treatment

Abstract

Despite being a standard process in fabrication of organic thin-film transistors (TFTs) to reduce interface trap density and decrease surface energy, self-assembled monolayer (SAM) treatment of gate dielectrics is rarely used in oxide-semiconductor-based TFTs due to possible damage to the SAM during semiconductor deposition. Here, by studying the dependence of plasma damage to SAM on the deposition conditions of InGaZnO (IGZO) semiconductor thin films, the feasibility of enhancing the performance of oxide TFTs using octadecyltrichlorosilane (OTS)-treated, ultra-thin AlxOy gate dielectrics is explored. It is discovered that under optimized conditions, the TFTs can be significantly improved, showing a reduction of interface trap density by 50% and an increase of carrier mobility and current on/off ratio by a factor of 2.3 and 76, respectively. The effects on bias stress stability also show substantial improvement after the SAM interface treatment. Finally, such an optimized condition is found to also work for IGZO TFTs gated with OTS-treated HfOx, showing an increase of mobility from 7.8 to 16 cm2 V−1 s−1 compared with the untreated devices. As a result, this simple and yet effective interface treatment method and the resulting devices may have potential applications in future low-cost, low-power electronics.