A simplified encapsulation strategy for metal-oxide based TFTs, using ozone instead of water as an oxygen source in a low-temperature ALD process is demonstrated. Thereby, the threshold voltage remains unaltered and the hysteresis is permanently reduced. Costly energy- and time-consuming post-treatment processes can be avoided. This concept is widely applicable to various encapsulation materials (e. g., Al2O3, TiO2, ZrO2) and metal-oxide channel semiconductors (e. g., zinc-tin-oxide (ZTO), indium-gallium-zinc-oxide (IGZO)).