Thickness-modulated metal-to-semiconductor transformation in a transition metal dichalcogenide.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 29500434.
- Also identified by DOI 10.1038/s41467-018-03436-0 and PMC identifier 5834615.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The possibility of tailoring physical properties by changing the number of layers in van der Waals crystals is one of the driving forces behind the emergence of two-dimensional materials. One example is bulk MoS<sub>2</sub>, which changes from an indirect gap semiconductor to a direct bandgap semiconductor in the monolayer form. Here, we show a much bigger tuning range with a complete switching from a metal to a semiconductor in atomically thin PtSe<sub>2</sub> as its thickness is reduced. Crystals with a thickness of ~13 nm show metallic behavior with a contact resistance as low as 70 Ω·µm. As they are thinned down to 2.5 nm and below, we observe semiconducting behavior. In such thin crystals, we demonstrate ambipolar transport with a bandgap smaller than 2.2 eV and an on/off ratio of ~10<sup>5</sup>. Our results demonstrate that PtSe<sub>2</sub> possesses an unusual behavior among 2D materials, enabling novel applications in nano and optoelectronics.