Coupling Top- and Bottom-Gate ZnO Thin Film Transistors for Low Voltage, High Gain Inverter

Abstract

We reported on the fabrication of depletion-load-type ZnO thin film transistor (TFT) inverters coupling top-and bottom-gate TFTs that have 20 nm thin Al2O3 dielectrics grown by atomic layer deposition. Because the top-gate ZnO TFT showed a lower field-effect mobility of 0.1 cm(2)/V s than that of the bottom-gate device (2.4 cm(2)/V s), we used the top-and bottom-gate structures as driver and load transistors, respectively, to adjust the transition voltage of the inverter with an identical width/length dimension for both TFTs. Our ZnO inverter demonstrated an excellent voltage gain of similar to 41 at a low supply voltage of 5 V.