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Universal Fermi-Level Pinning in Transition-Metal Dichalcogenides
Kai Sotthewes1,2, Rik van Bremen1, Edwin Dollekamp1
1Physics of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede, The Netherlands.
Summary
Metal-induced gap states (MIGS) cause Fermi-level pinning (FLP) in transition-metal dichalcogenide (TMDC) semiconductor junctions. Defects further enhance FLP, impacting electron transport in TMDC devices.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Electron transport in transition-metal dichalcogenide (TMDC)-based semiconductor/metal junctions is crucial for optoelectronic devices.
- Fermi-level pinning (FLP) in TMDCs limits Schottky barrier height tunability, hindering device performance.
Purpose of the Study:
- To investigate the origin of Fermi-level pinning (FLP) in transition-metal dichalcogenide (TMDC) semiconductor/metal junctions.
- To differentiate the impact of pristine and defected regions on electron transport properties.
Main Methods:
- Utilized high-spatial-resolution surface characterization techniques.
- Investigated a variety of TMDCs including MoSe2, WSe2, WS2, and MoTe2.
- Analyzed electron transport mechanisms in metal/semiconductor junctions.
Main Results:
- Metal-induced gap states (MIGS) were identified as the primary cause of FLP in pristine TMDC regions.
- Disorder-induced gap states, stemming from transition-metal vacancies or substitutionals, further amplify FLP in defected regions.
- Schottky barrier heights in pristine regions are explained by MIGS, leading to partial FLP.
Conclusions:
- MIGS are confirmed as the origin of FLP in TMDC-based metal/semiconductor junctions.
- Defects significantly influence electron transport properties and enhance FLP in TMDC devices.
- Understanding these mechanisms is vital for designing efficient TMDC-based electronic and optoelectronic devices.
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