Nonvolatile MoS₂ field effect transistors directly gated by single crystalline epitaxial ferroelectric

We demonstrate non-volatile, n-type, back-gated, MoS₂ transistors, placed directly on an epitaxial grown, single crystalline, PbZr_0.2Ti_0.8O₃ (PZT) ferroelectric. The transistors show decent ON current (19 μA/μm), high on-off ratio (10⁷), and a subthreshold swing of (SS ∼ 92 mV/dec) with a 100 nm thick PZT layer as the back gate oxide. Importantly, the ferroelectric polarization can directly control the channel charge, showing a clear anti-clockwise hysteresis. We have self-consistently confirmed the switching of the ferroelectric and corresponding change in channel current from a direct time-dependent measurement. Our results demonstrate that it is possible to obtain transistor operation directly on polar surfaces, and therefore, it should be possible to integrate 2D electronics with single crystalline functional oxides.