Sign-changing non-monotonic voltage gain of HfO2/Parylene-C/SrTiO3 field-effect transistor due to percolative insulator to two-dimensional metal transition

Controlling the insulator-to-2D-metal transition is a promising key to overcome the scaling problem that silicon-based electronic devices will face in the near future. In this context, we examine the channel formation of SrTiO3-based solid-gated field-effect devices in which a 2D metal phase coexists with a semiconductor phase. A non-monotonic voltage-gain transfer characteristic with negative and positive slope regions is observed. We introduce a numerical model that helps to rationalize the experimental findings in terms of the established physics of field-effect transistors and percolation. Our numerical study not only reproduces the experimental results but also provides non-trivial predictions, which we verify experimentally.