Low-Temperature ZnO TFTs Fabricated by Reactive Sputtering of Metallic Zinc Target

A low-temperature metallic-zinc-target reactive sputtering technology is used to fabricate a ZnO thin-film transistor (TFT). The effect of the $\hbox {O}_{2}/\hbox {Ar}$ flow rate ratio on the performance of the resulting TFTs is investigated in detail. It is found that an $\hbox {O}_{2}/\hbox {Ar}$ ratio of 0.75–0.8 produces devices with the best performance. The maximum processing temperature used in this brief is 150 $^{\circ}\hbox {C}$ , and the fabricated TFTs have a saturation mobility of 7.4 $\hbox {cm}^{2}/(\hbox {V}\cdot \hbox {s})$ , an on–off current ratio of more than $\hbox {1} \times \hbox {10}^{7}$ , and a subthreshold swing of 0.58 V/dec. Experimental results also show that using $\hbox {SiO}_{x}$ as gate dielectric instead of $\hbox {SiN}_{x}$ can improve both carrier mobility and subthreshold.