A Method for Characterizing the Optical Anisotropy of Van der Waals Crystals with Nanoscale Thickness
An anisotropy and crystal optics technology, applied in the direction of testing crystals, material analysis through optical means, scientific instruments, etc., can solve problems that are not suitable for the characterization of van der Waals crystal optical anisotropy, and overcome the limitation of sample size, Accurately Characterized Effects
Active Publication Date: 2020-04-21
THE NAT CENT FOR NANOSCI & TECH NCNST OF CHINA
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Problems solved by technology
The traditional methods for characterizing the optical anisotropy of materials mainly include end-face reflection method and ellipsometry. However, these two methods are not suitable for the characterization of the optical anisotropy of van der Waals crystals, because they all require the sample to have a size of at least 50 microns. However, the size of van der Waals crystals obtained by mechanical exfoliation is generally on the order of several microns.
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[0027] Take van der Waals crystal MoS 2 Nanosheets are taken as an example, and the optical anisotropy thereof is accurately characterized using the method described in the present invention.
[0028] see Figure 1-Figure 3 , the present invention provides a method for characterizing the optical anisotropy of van der Waals crystals with nanoscale thickness, the steps are as follows:
[0029] figure 1 It is a structural schematic diagram of the measurement experiment setup in the present invention. Such as figure 1 As shown, the cantilever with the tip of the scattering scanning near-field optical microscope (s-SNOM) is used as the reference object, where k 0 represents the vacuum wave vector, k xy for k 0 Projection on the measured sample plane, α is k xy with k 0 angle, and α=38°, k xy The included angle with the edge of the sample to be tested is β=60°; when λ=1530nm and the spot diameter is 3μm, the near-infrared laser is irradiated on the tip of the s-SNOM to exci...
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Abstract
The invention provides a method for representing optical anisotropy of Van der Waals crystal with nanometer thickness. Ordinary and unusual waveguide modes are excited in the Van der Waals crystal byusing a scatter-scanning near field optical microscope (s-SNOM), the waveguide modes are subjected to near-field imaging, and the near-field imaging is analyzed to acquire the optical anisotropy of the Van der Waals crystal. With the method, limitation of traditional representation means on sample sizes is overcome, and the optical anisotropy of single-axis and biaxial Van der Waals crystal materials can be represented precisely.
Description
technical field [0001] The invention relates to the field of measuring properties of Van der Waals crystal materials, in particular to a method for characterizing the optical anisotropy of Van der Waals crystals with nanoscale thickness by using a scattering scanning near-field optical microscope. Background technique [0002] After graphene, new two-dimensional materials (such as hexagonal boron nitride, molybdenum disulfide, etc.) continue to emerge. These new two-dimensional materials (van der Waals crystals) can be prepared by physical exfoliation or chemical growth methods. Among them, the two-dimensional materials prepared by the physical mechanical exfoliation method can maintain a good crystal structure, maintain good electrical and optical properties, and can be easily prepared into high-quality functional devices. Recently, the academic community has proposed a new concept of van der Waals heterojunction, which regulates the function and performance of the prepare...
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IPC IPC(8): G01N21/84
CPCG01N21/84G01N2021/8477
Inventor 戴庆胡德波杨晓霞李驰刘瑞娜胡海刘梦昆
Owner THE NAT CENT FOR NANOSCI & TECH NCNST OF CHINA