Suppressing Hydrogen-related Trap States in indium–gallium–zinc oxide thin-film transistors for High-Mobility and Low-Power Oxide Electronics

Abstract

Controlling defect states and impurity incorporation in oxide semiconductors is crucial for advancing high-performance thin-film transistors. Here we show that hydrogen impurities act predominantly as deep-level electron traps, critically limiting both performance and reliability. Using density functional theory calculations supported by experimental analysis, we demonstrate that suppressing hydrogen incorporation markedly improves device characteristics. Indium–gallium–zinc oxide transistors fabricated under hydrogen-controlled conditions exhibit enhanced bias stability and, with an aluminum electron-injection layer, achieve a high field-effect mobility of about 120 cm2/V·s, nearly twice that of devices processed in hydrogen-rich environments. These devices also support highspeed switching up to 1 MHz. When integrated with a negative capacitance structure, they exhibit subthreshold swing values as low as 39 mV/dec, surpassing the thermionic limit. Inverter circuits with hydrogen-suppressed IGZO TFTs with an aluminum electron-injection layer deliver a gain of ~50, far exceeding the ~10 of conventional counterparts. These findings highlight hydrogen control as a key enabler of low-power, high-speed oxide electronics.