High-Performance FETs with High-<i>k</i> STO by Optimized van der Waals Heterostructure Interface

The pursuit of suitable insulating layers and high-quality integration methods is important to further improve the performance of field-effect transistors (FETs). In this study, we employ transferable high-<i>k</i> oxide films as device gate dielectrics to fabricate high-quality optoelectronic devices by optimizing the interface between the dielectric material and the two-dimensional (2D) materials. Through meticulous refinement, a transferred film roughness of 269.27 pm was achieved, resulting in intact, crack-free SrTiO₃ films. The molybdenum disulfide (MoS₂) transistors exhibited remarkable characteristics, including a high on/off ratio (<i>I</i>_ON/<i>I</i>_OFF) of 1 × 10⁸, a subthreshold swing as low as 69.2 mV/dec, and a field-effect mobility reaching 230 cm²/(V·s). Additionally, the SrTiO₃ films were combined with molybdenum telluride (MoTe₂) to fabricate PN junctions capable of functioning as photodetectors at extremely low operating voltages (±2 V). The exceptional performance of both the MoS₂ FETs and the MoTe₂ PN junctions can be attributed to the optimized, high-quality dielectric/semiconductor heterojunction interface. This further demonstrates the versatility of the van der Waals integration method employed in this research.