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Interlayer bond polarizability model for interlayer phonons in van der Waals heterostructures
Rui Mei1,2, Miao-Ling Lin1, Heng Wu1,2
1State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China. phtan@semi.ac.cn.
Nanoscale
|February 8, 2024
Summary
A new model quantifies Raman intensity of layer-breathing modes in complex 2D materials. This improved interlayer bond polarizability model (IBPM) accurately predicts Raman spectra for van der Waals heterostructures.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Spectroscopy
Background:
- Raman scattering reveals crucial solid-state properties like phonons and electronic structures.
- The classical bond polarizability model struggles to quantify Raman peak intensities.
- The interlayer bond polarizability model (IBPM) was developed for 2D materials but faces challenges with van der Waals heterostructures (vdWHs).
Purpose of the Study:
- To quantitatively understand the Raman intensity of layer-breathing modes (LBMs) in polynary van der Waals heterostructures (vdWHs).
- To investigate the influence of excitation energy and twisted multilayer graphene (tMLG) twist angle on LBM intensity.
- To develop an improved IBPM capable of predicting LBM intensity in complex vdWHs.
Main Methods:
- Experimental observation of LBMs in vdWHs composed of tMLG, MoS2, and hBN.
- Systematic variation of excitation energy and tMLG twist angle.
- Development and application of an improved IBPM to analyze Raman intensity data.
Main Results:
- Observed LBMs in tMLG-based vdWHs with intensity dependent on excitation energy and tMLG twist angle.
- Demonstrated resonance effects where LBM intensity changes significantly when excitation energy matches electronic states of tMLG or MoS2.
- Validated the improved IBPM's ability to quantitatively predict LBM intensity, including emergence/absence of modes.
Conclusions:
- The improved IBPM accurately quantifies LBM intensity in complex, polynary vdWHs.
- This model successfully accounts for resonant excitation effects with specific constituent electronic states.
- The enhanced IBPM offers a powerful tool for understanding and predicting Raman spectra in advanced 2D materials and heterostructures.
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