High performance ZnO-thin-film transistor with Ta2O5 dielectrics fabricated at room temperature

Abstract

The authors report on the fabrication of low-driven-voltage and high mobilityZnOthin-film transistor with sputtering Ta 2 O 5 film as the dielectric. The device shows a field effect mobility of 60.4 cm 2 / V s , a threshold voltage of 1.1 V, an on/off ratio of 1.22 × 10 7 , and a subthreshold swing of 0.23 V/decade. The high mobility partially resulted from the fringing-electric-field effect due to the undefined active layer. Therefore, considering our device geometry, the actual mobility is about 40.5 cm 2 / V s . We contribute the high performance to the proper dielectric thickness, smooth insulator surface, and relatively low trap state densities in the insulator/channel interface.