High performance ZnO-thin-film transistor with Ta_2O_5 dielectrics fabricated at room temperature

摘要

The authors report on the fabrication of low-driven-voltage and high mobility ZnO thin-film transistor with sputtering Ta_2O_5 film as the dielectric. The device shows a field effect mobility ofrn60.4 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 aboutrn40.5 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.