Ultimate limit in size and performance of WSe<sub>2</sub> vertical diodes.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 30560877.
- Also identified by DOI 10.1038/s41467-018-07820-8 and PMC identifier 6299081.
- 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
Precise doping-profile engineering in van der Waals heterostructures is a key element to promote optimal device performance in various electrical and optical applications with two-dimensional layered materials. Here, we report tungsten diselenide- (WSe<sub>2</sub>) based pure vertical diodes with atomically defined p-, i- and n-channel regions. Externally modulated p- and n-doped layers are respectively formed on the bottom and the top facets of WSe<sub>2</sub> single crystals by direct evaporations of high and low work-function metals platinum and gadolinium, thus forming atomically sharp p-i-n heterojunctions in the homogeneous WSe<sub>2</sub> layers. As the number of layers increases, charge transport through the vertical WSe<sub>2</sub> p-i-n heterojunctions is characterized by a series of quantum tunneling events; direct tunneling, Fowler-Nordheim tunneling, and Schottky emission tunneling. With optimally selected WSe<sub>2</sub> thickness, our vertical heterojunctions show superb diode characteristics of an unprecedentedly high current density and low turn-on voltages while maintaining good current rectification.