Enhanced Performance in Al-Doped ZnO Based Transparent Flexible Transparent Thin-Film Transistors Due to Oxygen Vacancy in ZnO Film with Zn–Al–O Interfaces Fabricated by Atomic Layer Deposition

Highly conductive and optical transparent Al-doped ZnO (AZO) thin film composed of ZnO with a Zn-Al-O interface was fabricated by thermal atomic layer deposition (ALD) method. The as-prepared AZO thin film exhibits excellent electrical and optical properties with high stability and compatibility with temperature-sensitive flexible photoelectronic devices; film resistivity is as low as 5.7 × 10^-4 Ω·cm, the carrier concentration is high up to 2.2 × 10²¹ cm^-3. optical transparency is greater than 80% in a visible range, and the growth temperature is below 150 °C on the PEN substrate. Compared with the conventional AZO film containing by a ZnO-Al₂O₃ interface, we propose that the underlying mechanism of the enhanced electrical conductivity for the current AZO thin film is attributed to the oxygen vacancies deficiency derived from the free competitive growth mode of Zn-O and Al-O bonds in the Zn-Al-O interface. The flexible transparent transistor based on this AZO electrode exhibits a favorable threshold voltage and I_on/I_off ratio, showing promising for use in high-resolution, fully transparent, and flexible display applications.