Effects of gamma-ray irradiation and electrical stress on ZnO thin film transistors

Radiation tolerance is of interest in electronic applications such as radiation sensors, nuclear reactors, x-ray imagers, and high-energy particle accelerators. While properly designed Si MOSFETS are usefully radiation resistant, most thin-film transistors (TFTs), including polysilicon and a-Si:H, are severely degraded by relatively low irradiation dose (typically <;1 Mrad) [1, 2]. We previously reported gamma ray radiation exposure results for unbiased ZnO TFTs and circuits and found only small electrical changes for doses up to 100 Mrad [3]. For applications with TFTs operating in harsh radiation environments, the effects of simultaneous electrical stress and radiation exposure are important. We report here the effects of ⁶⁰Co gamma irradiation and electrical stress on the characteristics of ZnO TFTs with active and dielectric layers deposited by weak-oxidant plasma enhanced atomic layer deposition (PEALD).