35 lines
2.3 KiB
XML
35 lines
2.3 KiB
XML
== Raman experiments setup
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拉曼设备的型号。激光的波长，背散射。共焦针孔。
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拉曼设备的型号是 LabRAM HR Evolution，使用背散射。
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大部分实验中，我们使用 532 nm 的激光，少部分实验中使用 325 nm 的激光以观测紫外拉曼。
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All Raman experiments were conducted using a LabRAM HR Evolution system in a back-scattering configuration,
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where the scattered light was collected in the direction opposite to the incident laser.
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A 532 nm laser was primarily used as the excitation source,
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while a 325 nm laser was employed for only ultraviolet Raman measurements.
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三个入射方向配置
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有三个不同的入射配置，包括正入射、掠入射、边入射。
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考虑到 4 度斜切和 4H-SiC 几乎各向同性的折射率（2.73） @shaffer_refractive_1971 ，掠入射的入射角大约为 25 度。
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在正散射过程中，我们使用 100 微米的共焦针孔，以尽可能提高 z 方向的分辨率 @song_depth_2020；其它情况使用常用的 200 微米针孔以提高信噪比。
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此外，在正入射和边入射时，拉曼散射信号较强，因此我们使用较短的积分时间（约 60 秒），
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而在掠入射时，拉曼信号较弱，因此使用较长的积分时间（约 300 秒）。
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Three distinct incidence configurations were utilized, as illustrated in @figure-incidence:
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(i) normal incidence, where the laser incident perpendicularly to the epitaxial surface;
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(ii) grazing incidence, where the laser incident nearly parallelly to the epitaxial surface;
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and (iii) edge incidence, where the laser is incident at the wafer edge and perpendicularly to the edge surface.
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Considering the 4° offcut angle and the nearly isotropic refractive index of 2.73 for 4H-SiC @shaffer_refractive_1971,
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the refracted laser in grazing incidence forms an angle of approximately 25° with the c axis.
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A 100 μm confocal pinhole was used for normal incidence to enhance axial (z-direction) resolution @song_depth_2020,
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while a 200 μm pinhole was employed for the other configurations to improve the signal-to-noise ratio.
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The integration time was set to 60 seconds for normal and edge incidence,
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while it was extended to 300 seconds for grazing incidence due to the weaker Raman signal.
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偏振的配置？
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#include "figure-incidence.typ"
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