Amorphous Ga ₂ O ₃ Semiconductor: A New Solution for Robust X‐Ray Dosimeters

Abstract As most commonly used miniature solid‐state dosimeter, metal‐oxide‐semiconductor field effect transistors (MOSFETs) have been facing unavoidable gate leakage and robustness problems due to the double‐sided role of traps in oxide insulators. Herein, a new solution for X‐ray dosimeter has been proposed which leverages the conductivity change of amorphous Ga ₂ O ₃ (a‐Ga ₂ O ₃ ) channel instead of charge trapping in oxide insulators. Increasingly negatively‐shifted threshold voltage (V _th ) of a‐Ga ₂ O ₃ thin‐film transistor is recorded together with almost unchanged subthreshold swing (SS) and field‐effect mobility (µ _FE ) after X‐ray irradiations. X‐ray‐induced‐variation of oxygen vacancy (V _O ) related defects in a‐Ga ₂ O ₃ is revealed after a combined investigation of X‐ray photoelectron spectroscopy (XPS) and neutron reflectivity (NR) measurements, contributing to the indicative V _th shift related with X‐ray dosage. A functional recovery is realized through an annealing process in air condition, showing the high reliability of a‐Ga ₂ O ₃ semiconductor. Moreover, the unique merit of no need for power supply during X‐ray irradiations, beneficial from the slow neutralization rate of ionized V _O related defects, imparts an offline working capability to the dosimeter. This work provides a potential strategy to monitor X‐ray dosage via utilizing the X‐ray‐induced change of amorphous oxide semiconductor conductivity, hence addressing the reliability and repeatability issues in present MOSFET devices.