Study on the complex refractive index of twisted bilayer graphene grown on a SiO2/Si substrate

IF 4 3区工程技术 Q2 ENGINEERING, ELECTRICAL & ELECTRONIC

Optical and Quantum Electronics Pub Date : 2025-09-25 DOI:10.1007/s11082-025-08460-1

Chun-Lin Wu, Jia-Le Wang, Xin-Wen Wang, Ming-Ming Yang, Hong Zheng, Xuan-Yu Mu, Wei Dang, Ri-Dong Cong, Xiao-Li Li

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Abstract

This study investigates the complex refractive index (\(\:\stackrel{\sim}{n}=n-ik\)) of twenty-four twisted bilayer graphene (tBLG) samples on SiO₂/Si substrates using microscopic reflection spectroscopy. By constructing optical contrast (OC) spectra from the interference patterns between tBLG and the underlying SiO₂/Si substrate, we identified anomalous absorption peaks at wavelengths that depend on the twist angle (θt). A multilayer dielectric structure transfer matrix model was employed to correlate the OC spectra with the complex refractive index of tBLG. The complex refractive index was calculated using two methods, with the thicknesses of tBLG (d₁) and SiO₂ (d₂) as adjustable parameters. The results reveal significant variations in both n and k values at wavelengths corresponding to the anomalous absorption peaks, underscoring the substantial impact of θt on the complex refractive index of graphene.

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在SiO2/Si衬底上生长的扭曲双层石墨烯复折射率的研究

本研究利用显微反射光谱研究了24个扭曲双层石墨烯（tBLG）样品在sio2 /Si衬底上的复折射率（\(\:\stackrel{\sim}{n}=n-ik\)）。通过从tBLG与底层sio2 /Si衬底之间的干涉图构建光学对比（OC）光谱，我们在依赖于扭转角（θt）的波长处发现了异常吸收峰。采用多层介质结构转移矩阵模型，将OC谱与tBLG复折射率进行关联。以tBLG （d1）和SiO₂（d2）厚度为可调参数，采用两种方法计算复折射率。结果显示，在异常吸收峰对应的波长处，n和k值都发生了显著变化，强调了θt对石墨烯复折射率的实质性影响。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Optical and Quantum Electronics 工程技术-工程：电子与电气

CiteScore

4.60

自引率

20.00%

发文量

810

审稿时长

3.8 months

期刊介绍： Optical and Quantum Electronics provides an international forum for the publication of original research papers, tutorial reviews and letters in such fields as optical physics, optical engineering and optoelectronics. Special issues are published on topics of current interest. Optical and Quantum Electronics is published monthly. It is concerned with the technology and physics of optical systems, components and devices, i.e., with topics such as: optical fibres; semiconductor lasers and LEDs; light detection and imaging devices; nanophotonics; photonic integration and optoelectronic integrated circuits; silicon photonics; displays; optical communications from devices to systems; materials for photonics (e.g. semiconductors, glasses, graphene); the physics and simulation of optical devices and systems; nanotechnologies in photonics (including engineered nano-structures such as photonic crystals, sub-wavelength photonic structures, metamaterials, and plasmonics); advanced quantum and optoelectronic applications (e.g. quantum computing, memory and communications, quantum sensing and quantum dots); photonic sensors and bio-sensors; Terahertz phenomena; non-linear optics and ultrafast phenomena; green photonics.