Simultaneous enhancement of electrical performance and stability of zinc-tin-oxide thin-film transistors by tantalum doping

In this paper, solution-processed tantalum-doped zinc-fin-oxide (TZTO) thin films were explored as channel layer for high performance thin-film transistors (TFTs). The microstructure, surface morphology and oxygen defects states properties of the thin films with various tantalum concentration were investigated by Grazing incidence X-ray diffraction, Atomic force microscopy and X-ray photoelectron spectroscopy, respectively. It was found that the TZTO thin films exhibit amorphous microstructure nature; its surface roughness and the oxygen vacancies change greatly with different tantalum doping concentration. Then, TFTs with TZTO channel layer were fabricated, and the electrical performance were also evaluated. The results indicate that tantalum atom is able to act as a carrier generator and oxygen vacancy suppressor simultaneously, which correspondingly enhance the mobility and stability of the devices. 2% tantalum doped devices show optimized electrical characteristics with a current on/off ratio of 10(7), a threshold voltage of 9.2 V, a subthreshold swing of 0.82 V/Dec and a field effect mobility of 2.24 cm(2)/Vs as well as excellent bias stress stability.