Abstract
Because of the chemical inertness of two dimensional (2D) hexagonal-boron nitride (h-BN), few atomic-layer h-BN is often used to encapsulate air-sensitive 2D crystals such as black phosphorus (BP). However, the effects of h-BN on Schottky barrier height, doping, and contact resistance are not well-known. Here, we investigate these effects by fabricating h-BN encapsulated BP transistors with cobalt (Co) contacts. In sharp contrast to directly Co contacted p-type BP devices, we observe strong n-type conduction upon insertion of the h-BN at the Co/BP interface. First-principles calculations show that this difference arises from the much larger interface dipole at the Co/h-BN interface compared to the Co/BP interface, which reduces the work function of the Co/h-BN contact. The Co/h-BN contacts exhibit low contact resistances (∼4.5 kω) and are Schottky barrier-free. This allows us to probe high electron mobilities (4,200 cm2/(V s)) and observe insulator-metal transitions even under two-terminal measurement geometry.
Original language | English |
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Pages (from-to) | 5361-5367 |
Number of pages | 7 |
Journal | Nano Letters |
Volume | 17 |
Issue number | 9 |
DOIs | |
Publication status | Published - 13 Sept 2017 |
Keywords
- black phosphorus
- boron nitride
- encapsulation
- tunnel barrier
- Work-function
ASJC Scopus subject areas
- Bioengineering
- General Chemistry
- General Materials Science
- Condensed Matter Physics
- Mechanical Engineering