paper: result/perfect 第一段

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== Phonons in Perfect 4H-SiC == Phonons in Perfect 4H-SiC
These phonons were categorized into two groups and discussed separately, according to their electrical polarities: // 第一段:弱极性与强极性声子模式表现截然不同。如图所示,弱极性声子模式几乎不依赖于波矢方向,而强极性声子模式则表现出显著的各向异性。
negligible-polarity phonons (i.e., zero or very weak electrical polarity), and strong-polarity phonons.
Owing to the distinct behaviors arising from their different electrical polarities,
Raman-active phonons were categorized into two groups:
negligible-polarity phonons (i.e., having zero or very weak electrical polarity),
and strong-polarity phonons.
The negligible-polarity phonons exhibited minimal dependence on the wavevector direction
(see the intersection of gray solid lines and orange dashed lines in @figure-discont b and c),
and were therefore usually analyzed at the #sym.Gamma point regardless of the incidence configurations;
specifically, there were eight such modes
labeled A#sub[1]-1 to A#sub[1]-2, E#sub[1]-1 to E#sub[1]-2, and E#sub[2]-1 to E#sub[2]-4,
according to their irreducible representations in the C#sub[6v] group and in order of increasing frequency.
In contrast, the strong-polarity phonons displayed significant anisotropy,
and required analysis under specific incidence configurations.
In this paper, we focused on incidence within the zOx plane,
where three modes were present and named according to their vibration directions:
TO-zOx (vibrating in the zOx plane and roughly perpendicular to the incidence direction),
TO-y (vibrating along the y-axis), and LO (vibrating roughly parallel to the incidence direction).
// 第二段:我们具体计算了模式对极性的依赖。可以看到,弱极性声子的变化极小。与实验比较,也验证了我们实验的准确性。
// 第三段:有两个弱极性模式还没有在实验上看到过。我们通过计算知道了它们的强度,并看到了其中一个。
// 第四段:声子模式的强度可以从理论上得到解释。
=== Negligible-polarity Phonons === Negligible-polarity Phonons
@@ -11,7 +33,7 @@ This simplification was justified because
the negligible-polarity phonon modes participated in Raman scattering the negligible-polarity phonon modes participated in Raman scattering
were nearly identical across all incidence configurations, were nearly identical across all incidence configurations,
with their frequencies differing by only #sym.tilde 0.1 cm#super[-1] with their frequencies differing by only #sym.tilde 0.1 cm#super[-1]
(see the intersection of gray solid lines and orange dashed lines in @figure-discont b and c).
There were eight Raman-active negligible-polarity modes in 4H-SiC at the #sym.Gamma point, There were eight Raman-active negligible-polarity modes in 4H-SiC at the #sym.Gamma point,
corresponding to three irreducible representations of the C#sub[6v] group (A#sub[1], E#sub[1], and E#sub[2]). corresponding to three irreducible representations of the C#sub[6v] group (A#sub[1], E#sub[1], and E#sub[2]).