Effects of Al2O3 surface passivation on the radiation hardness of IGTO thin films for thin-film transistor applications

• The effects of Al 2 O 3 surface passivation on the radiation hardness of IGTO TFTs were analyzed using a 3.5-MeV proton beam. • The radiation hardness of IGTO thin films was largely improved with a decrease in the thickness of the passivation layer. • The device with sputtering-based Al 2 O 3 layer exhibited a higher radiation resistance than that with ALD-based Al 2 O 3 layer. In this study, we examined the effects of aluminum oxide (Al 2 O 3 ) surface passivation on the radiation damage of indium-gallium-tin oxide (IGTO) thin films and radiation hardness of IGTO thin-film transistors (TFTs). The radiation hardness of the TFTs was investigated using a 3.5-MeV proton beam at a dose of 10 13 cm −2 . From the obtained results, it was observed that the radiation hardness significantly improved with a decrease in the thickness of the Al 2 O 3 passivation layer. In addition, the IGTO TFT passivated by an Al 2 O 3 thin film prepared using sputtering exhibited a higher radiation resistance than that passivated by an Al 2 O 3 thin film formed using the atomic layer deposition method, even when the film thickness was the same. From the thin-film analyses carried out on various Al 2 O 3 /IGTO samples before and after proton irradiation, it was observed that the thickness and deposition technique of the Al 2 O 3 passivation layer substantially affected the concentration of oxygen vacancies and hydrogen within the IGTO thin film after proton irradiation. Overall, our results showed that the passivation layer significantly affects the radiation hardness of oxide TFTs, and that it is necessary to optimize the thickness and deposition technique of the passivation layer to obtain radiation-tolerant oxide TFTs.