Ultimate Limit in Size and Performance of WSe2 Vertical Diodes
Abstract
Precise doping-profile engineering in van der Waals (vdW) heterostructures is a key element to promote optimal device performance in various electrical and optical applications with two-dimensional vdW materials. Here, we report tungsten diselenide-(WSe2) 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 WSe2 single crystals by direct evaporations of high and low work-function metals platinum and gadolinium. Since metal-induced dopings are restricted to the first few layers of WSe2, atomically sharp p-i-n heterojunctions are naturally formed in the homogeneous WSe2 layers. As the number of layers increases, charge transport through the vertical WSe2 p-i-n heterojunctions is characterized by a series of quantum tunneling events, namely direct tunneling, Fowler-Nordheim (FN), and Schottky emission (SE). With optimally selected WSe2 thickness, where FN and SE tunneling events prevail, our vertical heterojunctions show superb diode characteristics of an unprecedentedly high current density (>= 2 × 105 A/cm2) and low turn-on voltages while maintaining good current rectification.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- 2019
- Bibcode:
- 2019APS..MARF12011J