Large-scale integration of CaF2 with quasi-vdW interface on two-dimensional FETs

The field-effect transistors (FETs) using 2D materials as channel materials have received great attention in the future development of integrated circuits, where the selection of gate dielectrics with better interface and gate control capabilities has become a focal research area. In this work, we applied a large-scale CaF2 film as the top gate dielectric of the FETs, which achieved a subthreshold swing of 90 mV/dec, an on/off ratio of 106, and a transfer curve hysteresis window below 10 mV. Additionally, large-sized array devices were fabricated, which exhibited stable electrical performance. Theoretical calculations have shown the formation of a quasi-van der Waals interface without bonding between CaF2 and the channel, which is consistent with the results observed using transmission electron microscopy. Our work represents significant technological advances in the development of 2D FETs, holding profound implications for the future design and fabrication of low-power electronic devices.