Enhancing proton irradiation tolerance of a-IGZO thin-film transistors through hydrogen doping

Abstract

Amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) are promising candidates for next-generation electronic devices owing to high mobility, low processing temperature, and optical transparency. However, their vulnerability to high-energy proton irradiation severely limits device stability in radiation environments. This study presents a strategy for enhancing the proton irradiation tolerance of IGZO TFTs through hydrogen doping. Hydrogen was introduced into IGZO films by post-annealing in a 5% H₂/95% Ar atmosphere and quantified by elastic recoil detection (ERD) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). Upon 5 MeV proton irradiation at a dose of 10¹³ cm⁻², the hydrogen-doped IGZO TFTs exhibited excellent radiation stability, with a threshold voltage shift of only −0.5 V. Depth-profiled X-ray photoelectron spectroscopy (XPS) and thermal desorption spectroscopy (TDS) revealed that hydrogen doping suppresses the formation of oxygen vacancies and promotes the conversion of O–H to M–H bonds after proton irradiation, relative to undoped devices. These results suggest a dual mechanism: hydrogen passivates oxygen vacancies through site occupation, followed by M–H bond formation, and compensates for irradiation-induced excess carriers via conversion of O–H bonds to M–H bonds. This simple hydrogen annealing approach provides a practical and effective route to highly reliable, radiation-hard oxide semiconductor devices.