Materials Science and Engineering Calendar

Two-dimensional (2D) semiconductors are promising candidates to replace bulk-semiconductor channels for next generation electronics due to their atomically smooth surfaces that minimize scattering-induced carrier-transport degradation. However, this same attribute introduces a major challenge for the deposition of high-quality dielectrics at the sub-nanometer equivalent oxide thickness (EOT) due to the lack of surface dangling bonds. Here, we show that atomically thin carbon dots assemble into a closely packed monolayer on 2D materials, without hybridizing with underlying graphene or molybdenum disulfide (MoS2) channels, to form a van der Waals interfacial layer. This interfacial layer of carbon-dots then facilitates the conformal growth of ultrathin high-κ oxides with an EOT down to 0.6±0.1 nm, leakage current density below 10-4 A·cm-2, and a breakdown field of 28 MV·cm-1. With this approach, we then fabricate top-gated MoS2 transistors with a subthreshold swing of 60 mV·dec-1, hysteresis below 30 mV, and a near-zero threshold voltage (VT) for enhancement-mode operation, allowing integration into logic circuits operating at a low drive voltage of 0.5 V.