Patterning metal contacts on monolayer MoS ₂ with vanishing Schottky barriers using thermal nanolithography

Two-dimensional semiconductors, such as molybdenum disulfide (MoS ₂ ), exhibit a variety of properties that could be useful in the development of novel electronic devices. However, nanopatterning metal electrodes on such atomic layers, which is typically achieved using electron beam lithography, is currently problematic, leading to non-ohmic contacts and high Schottky barriers. Here, we show that thermal scanning probe lithography can be used to pattern metal electrodes with high reproducibility, sub-10-nm resolution, and high throughput (10 ⁵ μm ² h ⁻¹ per single probe). The approach, which offers simultaneous in situ imaging and patterning, does not require a vacuum, high energy, or charged beams, in contrast to electron beam lithography. Using this technique, we pattern metal electrodes in direct contact with monolayer MoS ₂ for top-gate and back-gate field-effect transistors. These devices exhibit vanishing Schottky barrier heights (around 0 meV), on/off ratios of 10 ¹⁰ , no hysteresis, and subthreshold swings as low as 64 mV per decade without using negative capacitors or hetero-stacks.