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Disorder-tuned conductivity in amorphous monolayer carbon
Huifeng Tian1, Yinhang Ma2, Zhenjiang Li1
1School of Materials Science and Engineering, Peking University, Beijing, China.
Nature
|March 1, 2023
Summary
Researchers tuned the disorder (DOD) and electrical conductivity of amorphous monolayer carbon (AMC) films by controlling growth temperatures. This links atomic structure to material properties, enabling new 2D electronic devices.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Correlating atomic configurations (degree of disorder - DOD) with properties in amorphous solids is challenging due to difficulties in determining 3D atomic positions.
- Two-dimensional (2D) systems offer a simpler approach for atomic imaging, aiding the study of amorphous materials.
- Previous studies visualized atomic configurations in amorphous monolayer carbon (AMC) but lacked a direct link to macroscopic properties.
Purpose of the Study:
- To establish a direct causal link between atomic-scale structures and macroscopic properties in amorphous monolayer carbon (AMC) films.
- To demonstrate facile tuning of the degree of disorder (DOD) and electrical conductivity in AMC by controlling growth temperatures.
- To develop a framework connecting microstructural parameters to electrical properties for 2D amorphous materials.
Main Methods:
- Growth of amorphous monolayer carbon (AMC) films at varying temperatures using laser-assisted depositions.
- Atomic-resolution electron microscopy to visualize atomic configurations, medium-range order (MRO), and nanocrystallite densities.
- Numerical calculations to establish a conductivity diagram based on microstructural parameters.
Main Results:
- Variable-range-hopping conductive AMC with medium-range order (MRO) was achieved at the pyrolysis threshold temperature.
- Increasing growth temperature by 25°C led to loss of MRO, rendering AMC electrically insulating with a 10^9-fold increase in sheet resistance.
- Two order parameters (presence/absence of MRO and nanocrystallite density) were identified to fully describe DOD.
Conclusions:
- The study successfully links atomic-scale structure (degree of disorder, MRO, nanocrystallite density) to electrical conductivity in 2D amorphous materials.
- Growth temperature is identified as a key parameter for tuning DOD and conductivity in AMC.
- This work advances the understanding of structure-property relationships in amorphous materials and opens avenues for 2D amorphous electronic devices.
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