The Investigation of Indium-Free Amorphous Zn-Al-Sn-O Thin Film Transistor Prepared by Magnetron Sputtering

The indium-free amorphous oxide semiconductor thin film transistor (AOS-TFT) with aluminum (Al) electrodes shows broad application prospects in new-generation display technologies, such as ultra-high definition large-screen display, OLED display and 3D display. In this work, the thin film transistor (TFT) with a zinc-aluminum-tin-oxide (ZATO) semiconductor as the active layer and an Al electrodes as the source and drain (S/D) was investigated. The optical, electrical and semiconductive properties of the ZATO films were evaluated by atomic force microscopy (AFM), ultraviolet-visible spectrophotometry and microwave photoconductivity decay (mu-PCD), respectively. The result shows that the film is smooth and transparent and has low localized states and defects at a moderate oxygen concentration (similar to 5%) and a low sputtering gas pressure (similar to 3 mTorr). After the analysis of the transfer and output characteristics, it can be concluded that the device exhibits an optimal performance at the 623 K annealing temperature with an I-on/I-off ratio of 5.5 x 10(7), an SS value of 0.15 V/decade and a saturation mobility (mu(sat)) of 3.73 cm(2)center dot V-1 center dot s(-1). The ZATO TFT at the 623 K annealing has a -8.01 V negative shift under the -20 V NBS and a 2.66 V positive shift under the 20 V PBS.

Automated summary

The study demonstrates that the TFT with ZATO semiconductor exhibits smooth and transparent characteristics under moderate oxygen concentration and low sputtering gas pressure, and shows optimal performance at a 623 K annealing temperature.