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Defect-Mediated Phase Transformation in Anisotropic Two-Dimensional PdSe2 Crystals for Seamless Electrical Contacts
Akinola D Oyedele, Shize Yang, Tianli Feng1
1Department of Physics and Astronomy and Department of Electrical Engineering and Computer Science , Vanderbilt University , Nashville , Tennessee 37235 , United States.
Journal of the American Chemical Society
|May 16, 2019
Summary
Stable Ohmic contacts for 2D materials are now achievable. A phase transformation in palladium diselenide (PdSe2) creates a metallic phase, forming seamless contacts and boosting transistor performance.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Achieving stable Ohmic contacts is a critical challenge for 2D material devices.
- Current limitations hinder the performance and integration of these advanced materials.
Purpose of the Study:
- To demonstrate a method for creating seamless Ohmic contacts in 2D material devices.
- To investigate a phase transformation in PdSe2 for improved electrical properties.
Main Methods:
- Inducing a phase transformation in PdSe2 using argon plasma.
- Utilizing cross-sectional scanning transmission electron microscopy (STEM).
- Employing theoretical calculations to understand the transformation mechanism.
Main Results:
- A contiguous metallic Pd17Se15 phase was successfully formed via plasma-induced selenium vacancies.
- The Pd17Se15/PdSe2 interface was atomically sharp and chemically bonded.
- Contacts exhibited low resistance (∼0.75 kΩ μm) and a low Schottky barrier height (∼3.3 meV).
- Carrier mobility in PdSe2 transistors increased nearly 20-fold compared to Ti/Au contacts.
Conclusions:
- Plasma-induced phase transformation offers a viable route to stable Ohmic contacts in 2D materials.
- The developed method significantly enhances the performance of PdSe2-based transistors.
- This approach paves the way for practical applications of 2D materials requiring efficient electrical contacts.
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