Low-voltage, solution-processed InZnO thin-film transistors with enhanced performance achieved by bilayer gate dielectrics

Fully solution-processed oxide thin-film transistors (TFTs) have shown a great potential in future printable electronics. However, high defect densities at the dielectric/channel interface have limited the simultaneous achievement of low operating voltage and high device performance. In this Letter, we study the effects of bilayer gate dielectrics in potential performance enhancement of solution-processed indium zinc oxide (IZO) TFTs. Several single and bilayer gate dielectrics are studied in terms of their physical and electrical properties. Compared with IZO TFTs using single-layer ZrOx gate dielectrics, optimized TFTs with ZrOx/AlOx gate dielectrics show an increase in carrier mobility and current on/off ratio by a factor of 3.5 and 27, respectively. The inner mechanisms of the performance enhancement are systematically studied, showing that the significantly improved TFT performance originates from the passivation effects of AlOx, which reduce the trap/defect states at the dielectric/channel interface by approximately an order of magnitude. With a low operating voltage of 2 V, a high mobility of over 10 cm(2)/V s, a subthreshold swing as low as 89 mV/dec, and a high current on/off ratio of >10(5), the reported devices might have a great potential in future low-cost, low-power printable electronics.

Automated summary

Fully solution-processed oxide thin-film transistors (TFTs) have great potential in future printable electronics. In this study, the effects of bilayer gate dielectrics on the performance of solution-processed indium zinc oxide (IZO) TFTs were investigated. The optimized TFTs with ZrOx/AlOx gate dielectrics showed significantly improved carrier mobility and current on/off ratio due to the passivation effects of AlOx, which reduced the trap/defect states at the dielectric/channel interface. With a low operating voltage of 2 V, high mobility, low subthreshold swing, and high current on/off ratio, these devices have great potential in future low-cost, low-power printable electronics.