Solution-Based CdS on HfO2 Thin Films for High-Gain and Low-Voltage Unipolar Inverters

We demonstrate low-temperature processed and high-gain unipolar inverters operating at voltages as low as V
_D
= 1 V. A maximum gain for a two-transistor unipolar inverter of 153 was achieved at V
_D
= 5 V with the advantage of using a solution-based n-type semiconductor and an entire fabrication process below 150 °C. We evaluate the impact of the gate dielectric thickness on the main thin-film transistor (TFT) parameters and operation voltage. In addition, we compare the conventional MOSFET square-law model indistinctly used in TFTs with a model specifically developed for TFTs. We demonstrate a methodology to model the TFT electrical characteristics and use the extracted parameters in SPICE simulations to evaluate different inverter configurations. Finally, we validate the SPICE simulations with our experiential results.