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Cross-Plane Carrier Transport in Van der Waals Layered Materials
Sina Najmaei1, Mahesh R Neupane1, Barbara M Nichols1
1Sensors and Electron Devices Directorate, United States Army Research Laboratory, 2800 Powder Mill Road, Adelphi, MD, 20783, USA.
Small (Weinheim an Der Bergstrasse, Germany)
|April 17, 2018
Summary
This study reveals how carriers move across transition metal dichalcogenide layers, focusing on thermal properties and van der Waals gaps. Understanding cross-plane transport opens new electronic applications for these materials.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Recent research on transition metal dichalcogenides (TMDs) primarily focused on in-plane electronic properties.
- The unique physical anisotropies and tunable interlayer interactions in TMDs necessitate investigation into their cross-plane (out-of-plane) electronic properties.
- Cross-plane transport is crucial for understanding short-channel physics and interlayer coupling in van der Waals materials.
Purpose of the Study:
- To investigate the mechanisms of carrier transport in the cross-plane crystal orientation of representative TMDs.
- To explore the influence of material thermal properties and van der Waals gaps on out-of-plane charge transport.
- To provide insights into the fundamental physics governing cross-plane electron transport in layered materials.
Main Methods:
- Temperature-dependent current-voltage (I-V) measurements were conducted on niobium diselenide and hafnium disulfide.
- First-principles simulations and a tunneling model were employed to analyze transport mechanisms and quantify parameters like barrier height and hopping distance.
- Raman spectroscopy was utilized to probe the thermal response of chemical bonds and understand van der Waals gap properties.
Main Results:
- Distinct cross-plane carrier transport characteristics were observed in niobium diselenide and hafnium disulfide.
- Results indicate that material thermal properties significantly influence out-of-plane transport.
- Thermally mediated carrier transport through van der Waals gaps was identified as a key mechanism.
Conclusions:
- The cross-plane electronic properties of TMDs are strongly linked to their thermal characteristics and the nature of their van der Waals gaps.
- Understanding these out-of-plane transport mechanisms is essential for unlocking new electronic applications of layered van der Waals materials.
- This research unravels complex physics and inspires future device designs based on TMDs.
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