Impact of Near-Stoichiometric Silicon Nitride Gate Insulator on the Performance of MOCVD-Grown ZnO Thin-Film Transistors

Abstract

ZnO Thin-film transistors (TFTs) on glass substrates were fabricated using plasma-deposited silicon nitride (SiN) gate insulators having two different compositions, namely nitrogen-rich and near-stoichiometric. The ZnO films were grown by metal organic chemical vapor deposition. The TFTs using near-stoichiometric SiN gate insulator exhibit better performance compared to those using nitrogen-rich SiN, and the performance improvement can be attributed to hydrogenation of the ZnO channel region by the gate dielectric. The positive impact of near-stoichiometric SiN gate insulator on TFT performance is further demonstrated in two more different types of ZnO TFTs. The two different types of TFTs are TFTs using a bilayer gate dielectric stack and TFTs using a MgZnO layer at channel/gate dielectric interface. Both types of TFTs exhibited excellent device characteristics.