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SiC-2nd-paper/test-typst/main.typ
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#import "@preview/starter-journal-article:0.4.0": article, author-meta
#import "@preview/tablem:0.2.0": tablem
#set par.line(numbering: "1")
// TODO: fix indent of first line
#show figure.caption: it => {
set text(10pt)
// TODO: how to align correctly?
align(center, box(align(left, it), width: 80%))
}
#set page(
// paper: "us-letter",
// header: align(right)[
// A fluid dynamic model for
// glacier flow
// ],
numbering: "1/1",
)
// TODO: why globally set placement not work?
// #set figure(placement: none)
#show: article.with(
title: "Article Title",
authors: (
"Haonan Chen": author-meta(
"xmu",
// email: "chn@chn.moe",
),
"Junyong Kang": author-meta(
"xmu",
email: "jykang@xmu.edu.cn"
)
),
affiliations: (
"xmu": "Xiamen University",
),
abstract: [#lorem(100)],
keywords: ("Typst", "Template", "Journal Article"),
// template: (body: (body) => {
// show heading.where(level: 1): it => block(above: 1.5em, below: 1.5em)[
// #set pad(bottom: 2em, top: 1em)
// #it.body
// ]
// set par(first-line-indent: (amount: 2em, all: true))
// set footnote(numbering: "1")
// body
// })
)
= Introduction
// SiC 是很好的材料。
// 其中4H-SiC 是SiC的一种多型它的性质更好近年来随着外延工艺的成熟而获得了更多的关注。
SiC is a promising wide-bandgap semiconductor material
with high critical electric field strength and high thermal conductivity.
It has been widely used in power electronic devices and has long attracted a lot of research
@casady_status_1996 @okumura_present_2006.
The 4H-SiC has a wider bandgap, higher critical electric field strength,
higher thermal conductivity, and higher electron mobility along the c-axis than other polytypes.
Currently, the 4H-SiC has gradually received more attention than other polytypes,
thanks to the development of epitaxy technology and the increasing application in the new energy industry
@tsuchida_recent_2018 @harada_suppression_2022 @sun_selection_2022. // TODO: 多引用一些近年来的文献,有很多
// 声子(量子化的原子振动)在理解晶体的原子结构以及热电性质方面起着重要作用。
// 声子可以通过多种实验技术来探测,包括 EELS、IR 吸收谱等。
// 拉曼光谱是最常用的方法,它提供了一种无损、非接触、快速和局部的声子测量方法,已被广泛用于确定晶体的原子结构(包括区分 SiC 的多型)。
Phonons (quantized atomic vibrations) play a fundamental role
in understanding the atomic structure
as well as the thermal and electrical properties
of crystals (including 4H-SiC).
They could be probed by various experimental techniques,
such as electron energy loss spectroscopy and infrared absorption spectroscopy.
Among these techniques,
Raman spectroscopy is the most commonly used method,
as it provides non-destructive, non-contact, rapid and spatially localized measurement of phonons
that near the #sym.Gamma point in reciprocal space.
Studies in Raman scattering of 4H-SiC have been conducted since as early as 1983
and have been widely employed to identification of different SiC polytypes.
// TODO: 增加引用文献
// 近年来,更多信息被从拉曼光谱中挖掘出来。
// LOPC 已经被用于快速估计 n 型 SiC 的掺杂浓度。
// 层错的拉曼光谱也已经被研究,可以被用于检测特定结构层错的存在和位置。
// 掺杂对拉曼光谱的潜在影响也已经被研究。
// 然而,拉曼光谱上仍有一些不知来源的峰;同时,一些也缺少一些理论上预测应该存在的峰。
// 此外,预测掺杂导致的新峰也没有说明原因。
Increasingly rich information has been extracted from Raman spectra of 4H-SiC.
Longitudinal optical phononplasmon coupling (LOPC) peek
has been utilized to rapidly estimate the doping concentration in n-type SiC.
Peeks associated with some stacking faults have also been investigated
and used to detect the presence and location of specific structural faults.
Moreover, the potential effects of doping on Raman spectra have been explored.
However, some unidentified peaks still appear in the Raman spectra,
while certain phonon modes predicted by theory remain unobserved.
In addition, the origins of newly emerged peaks induced by doping are often unclear or unexplained.
// TODO: 多举例,增加引用文献
In this paper, we do some things. Especially we do something for the first time.
// TODO: 完善
= Method
// TODO
calc
experiment
= Results and Discussion
== Phonons in Perfect 4H-SiC
// 拉曼活性的声子模式对应于 Gamma 点附近的声子模式。
// 根据这些声子模式的极性,我们将这些声子分成两类。
Raman scattering peeks correspond to atom vibrations (phonons) located near the #sym.Gamma point in reciprocal space,
and the exact location of these phonons is determined by the wavevectors of incident and scattered light.
On each site of the Brillouin zone near the #sym.Gamma point,
there are 21 phonon modes in 4H-SiC.
We classified these phonons into two categories based on their polarities.
18 of 21 phonons are classified into negligible-polar phonons (i.e., phonons with zero or very weak polarity),
for which the effect of polarity can be ignored in the Raman scattering process;
and the other three phonons are strong-polar phonons,
where the polarity gives rise to observable effects in the Raman spectra.
This classification is based on the fact that
the four Si atoms in the primitive cell carry similar positive Born effective charges (BECs),
and the four C atoms carry similar negative BECs (see @table-bec).
In the 18 negligible-polar phonons,
the vibrations of two Si atoms are approximately opposite to those of the other two Si atoms,
so do C atoms,
leading to cancellations of macroscopic polarity.
While in the three strong-polar phonons,
all Si atoms vibrate in the same direction, so do C atoms,
leading to a net dipole moment.
#figure(
table(columns: 4, align: center + horizon,
table.cell(colspan: 2)[], table.cell(colspan: 2)[*BEC* (unit: |e|)],
table.cell(colspan: 2)[], [x / y direction], [z direction],
table.cell(rowspan: 2)[Si atom], [A/C layer], [2.667], [2.626],
[B layer], [2.674], [2.903],
table.cell(rowspan: 2)[C atom], [A/C layer], [-2.693], [-2.730],
[B layer], [-2.648], [-2.800],
),
caption: [Born effective charges of Si and C atoms in A/B/C/B layers of 4H-SiC.],
placement: none,
)<table-bec>
=== Phonons with Negligible Polarities
// 我们使用 Gamma 点的声子模式来近似拉曼过程中的非极性声子。
// 这个近似被广泛使用,并且由于这个原因而被认为是可行的:
// 尽管拉曼过程中起作用的声子并不是那些严格在 Gamma 点的,
// 但这些声子模式的散射谱在 Gamma 附近连续且导数为零,且波矢很小(在本文中大约 0.01 A只有c轴的大约2%)。
// 因此,它们的性质与 Gamma 点的声子模式区别不大。
Phonons at the #sym.Gamma point were used
to approximate negligible-polar phonons that participating in Raman processes.
This approximation is widely adopted and justified by the fact that,
although the phonons participating in Raman processes are not these strictly located at the #sym.Gamma point,
their dispersion near the #sym.Gamma point is continuous with vanishing derivatives,
and their wavevector is very small (about 0.01 nm#super[-1] in back-scattering configurations with 532 nm laser light,
which corresponds to only 1% of the smallest reciprocal lattice vector of 4H-SiC),
as shown by the orange dotted line in @figure-discont.
Therefore, negligible-polar phonons involved in Raman processes
have nearly indistinguishable properties from those at the #sym.Gamma point,
and the phonon participating in Raman processes of different incident/scattered light directions
are all nearly identical to the phonons at the #sym.Gamma point.
#figure(
image("/画图/声子不连续/embed.svg"),
caption: [
(a) Phonon dispersion of 4H-SiC along the A#sym.GammaK high-symmetry path.
Gray lines represent negligible-polar phonon modes,
while colored lines indicate strong-polar phonon modes.
The green, red and blue lines indicate the mode along the z-direction, y-direction and x-direction, respectively.
Along A-#sym.Gamma path, strong-polar modes along x- and y-directions are degenerated,
showing as a single purple line.
(b) Magnified view of the boxed region in (a).
The orange dashed lines mark the phonon wavevectors involved in Raman scattering
with incident light along the z- and y-directions.
],
placement: none,
)<figure-discont>
// 这18个声子对应于 $\mathrm{C_{6v}}$ 点群的 14 个表示2A1 + 4B1 + 2E_1 + 4E2
// 其中B1 表示没有拉曼活性,它的拉曼张量为零;其它表示的拉曼张量不为零
// 但张量的大小是否足够大到可以在实验上看到,则还需要第一性原理计算,不能直接通过表示来判断。
The 18 negligible-polar phonons correspond to 14 irreducible representations of the C#sub[6v] point group:
2A#sub[1] + 4B#sub[1] + 2E#sub[1] + 4E#sub[2].
Phonons belonging to A#sub[1] and B#sub[1] representations vibration along z-axis and are non-degenerate,
while phonons belonging to E#sub[1] and E#sub[2] representations vibrate in plane and are doubly degenerate.
Phonons belonging to B#sub[1] representation are Raman-inactive, as their Raman tensors vanish.
In contrast, phonons belonging to other representations are Raman-active,
the Raman tensors of them have non-zero components,
indicating that these phonons might be visible in Raman experiment under appropriate polarization configurations.
// 各个模式的声子可以使用怎样的偏振光看到(即拉曼张量的非零分量)可以联合考虑 C6v 和 C2v 的表示来判断,如表所示。
// TODO: 翻译
However, the actual visibility of each phonon depends on the magnitudes of its Raman tensor components,
which cannot be computed solely from symmetry analysis.
// TODO: 画个表
Here we propose a method to estimate the magnitudes of the Raman tensors of these phonons.
// TODO: 写出来这个方法,并验证。
/*
这里应该有办法来估计。下面是我总结的规律:
按照我们规定的 ABCB 层序,并将拉曼张量的大小归结为键长的变化的话:
* 对于 E2 表示AC层运动方向必须相反B1/B2层运动方向必须相反因此只讨论A和B1层
* A 层内部的那个竖的键,同向运动会导致比较大的拉曼张量
* B1 层内部的那个竖的键,反向运动会导致比较大的拉曼张量
* A 层和 B1 层之间的那个横的键,反向运动会导致比较大的拉曼张量
我们或许可以通过这个路径来探索:
* 首先,根据 C3v 点群的表示,写出每个键的拉曼张量。这包括:
* 对于 A 内竖着的键,考虑连着的两个原子和第一近邻原子,对称性为 C3v。写出此时的拉曼张量。
* 对于 B1 内竖着的键,它也是 C3v它此时的拉曼张量是 h 下稍微变动的结果。写下这个结果。
* 对于 A 到 B1 的横着的键,它是 C3v 。写下这个结果。
* 对于 B1 到 C 的横着的键,它是 C3v 。写下这个结果为之前的结果的微微变动。
* 对于其它键,根据对称性由上面的结果直接写出。
* 写出各个模式的拉曼张量(上面的线性组合)。即可以直接看到结果。
*/
// 我们计算了拉曼活性声子的频率及拉曼张量,并与实验对比,如表如图所示。
// 其中有几个声子的拉曼活性较弱,有几个比较强。强的都可以在实验上看到;但弱的能否看到则取决于它是否恰好位于强模式的附近。
// 其中xxx 和xxx 位于强模式的附近它们在实验上无法看到xxx 只在 z 方向入射/散射时可以看到xxx 则在任意方向都能看到。
// 我们同样计算了这些声子在 300K 下的展宽,并与实验对比,结果如表所示。原子的振幅另外列于附录中。
The Raman tensors of these Raman-active phonons were calculated using first-principles methods,
and the results are summarized and compared with experimental results in @table-nopol.
Two Raman-active modes are not observed in our experiments,
including the E#sub[1] mode at 746.91 cm#super[-1] and the E#sub[2] mode at 764.33 cm#super[-1],
due to their relatively low Raman intensities, broad FWHM values, and their proximity to stronger modes.
The A#sub[1] phonon at 812.87 cm#super[-1] is Raman-active
in both in-plane (xx and xy) and out-of-plane (zz) polarization configurations,
but it is only visible when both the incident and scattered light propagate along the z-direction (zz),
as its Raman intensity in basal plane is too week to be distinguished from the noise.
We also calculated the linewidths of these phonons at 300 K and compared them with experimental results,
as summarized in the @table-nopol.
The atomic vibration amplitudes are listed separately in the Appendix.
// TODO: 将一部分 phonons 改为 phonon modes
// 在论文中我们这样来称呼phonon 对应某一个特征向量,而 modes 对应于一个子空间。
// 也就是说,简并的里面有两个或者无数个 phonon但只有一个 mode
#page(flipped: true)[#figure({
let m(n, content) = table.cell(colspan: n, content);
let m2(content) = table.cell(colspan: 2, content);
let m3(content) = table.cell(colspan: 3, content);
let A1 = [A#sub[1]];
// let A2 = [A#sub[2]];
let B1 = [B#sub[1]];
// let B2 = [B#sub[2]];
let E1 = [E#sub[1]];
let E2 = [E#sub[2]];
table(columns: 27, align: center + horizon, inset: (x: 3pt, y: 5pt),
// [*Direction of Incident & Scattered Light*],
// m(26)[Any direction (not depend on direction of incident & scattered light)],
// TODO: 整理表格,使用 m2 m3 来代替
[*Number of Phonon*],
// E2 E2 E1 2B1 A1 E1 E2 E2 A1 2B1
[1], m2[2], [3], m2[4], [5], [6], [7], [8], m3[9], [10], [11], [12], m2[13], [14], m2[15], m3[16], [17], [18],
[*Vibration Direction*],
// E2 E2 E1 2B1 A1
[x], m2[y], [x], m(2)[y], [x], [y], m(2)[z], m(3)[z],
// E1 E2 E2 A1 2B1
[x], [y], [x], m(2)[y], [x], m(2)[y], m(3)[z], m(2)[z],
[*Representation #linebreak() in Group C#sub[6v]*],
m(3, E2), m(3, E2), m(2, E1), B1, B1, m(3, A1), m(2, E1), m(3, E2), m(3, E2), m(3, A1), B1, B1,
[*Raman-active or Not*],
m(8)[Raman-active], m(2)[Raman-inactive], m(14)[Raman-active], m(2)[Raman-inactive],
// [*Representation in Group C#sub[2v]*],
// // E2 E2 E1 2B1 A1 E1 E2 E2 A1 2B1
// A2, m(2, A1), A2, m(2, A1), B2, B1, B1, B1, m(3, A1), B2, B1, A2, m(2, A1), A2, m(2, A1), m(3, A1), B1, B1,
[*Scattering in Polarization #linebreak() (non-zero Raman #linebreak() tenser components)*],
// E2 E2 E1 2B1 A1
[xy], [xx], [yy], [xy], [xx], [yy], [xz], [yz], m(2)[-], [xx], [yy], [zz],
// E1 E2 E2 A1 2B1
[xz], [yz], [xy], [xx], [yy], [xy], [xx], [yy], [xx], [yy], [zz], m(2)[-],
[*Raman Intensity (a.u.)*],
// E2 E2 E1 2B1 A1
m(3)[0.17], m(3)[1.13], m(2)[2.43], m(2)[0], m(2)[2.83], [1.79],
// E1 E2 E2 A1 2B1
m(2)[0.09], m(3)[88.54], m(3)[0.50], m(2)[0.01], [1.78], m(2)[0],
[*Visible in Common #linebreak() Raman Experiment or Not*],
// E2 E2 E1 2B1 A1
m(8)[Visible], m(2)[-], m(3)[Visible],
// E1 E2 E2 A1 2B1
m(2)[Invisible], m(3)[Visible], m(5)[Invisible], [Visible], m(2)[-],
[*Wavenumber #linebreak() (Simulation) (cm#super[-1])*],
// E2 E2 E1 2B1 A1
m(3)[190.51], m(3)[197.84], m(2)[257.35], [389.96], [397.49], m(3)[591.90],
// E1 E2 E2 A1 2B1
m(2)[746.91], m(3)[756.25], m(3)[764.33], m(3)[812.87], [885.68], [894.13],
[*Wavenumber #linebreak() (Experiment) (cm#super[-1])*],
// E2 E2 E1 2B1 A1
m(3)[195.5], m(3)[203.3], m(2)[269.7], m(2)[-], m(3)[609.5],
// E1 E2 E2 A1 2B1
m(2)[-], m(3)[776], m(5)[-], [839], m(2)[-],
[*FWHM #linebreak() (Simulation) (cm#super[-1])*],
// E2 E2 E1 2B1 A1
m(3)[0.08], m(3)[0.09], m(2)[0.08], m(2)[-], m(3)[0.61],
// E1 E2 E2 A1 2B1
m(2)[3.97], m(3)[4.62], m(3)[4.01], m(3)[0.89], m(2)[-],
[*FWHM #linebreak() (Experiment) (cm#super[-1])*],
// E2 E2 E1 2B1 A1
m(3)[1.11], m(3)[1.11], m(2)[1.11], m(2)[-], m(3)[591.90],
// E1 E2 E2 A1 2B1
m(2)[-], m(3)[1.11], m(3)[-], m(3)[1.11], m(2)[-],
[*Electrical Polarity*],
// E2 E2 E1 2B1 A1 E1 E2 E2 A1 2B1
m(6)[None], m(2)[Weak], m(2)[None], m(5)[Weak], m(6)[None], m(3)[Weak], m(2)[None],
)},
caption: [Negaligible-polarized Phonons at $Gamma$ Point],
)<table-nopol>]
#figure(
image("/画图/拉曼整体图/main.svg"),
caption: [
(a) Phonon dispersion of 4H-SiC along the A#sym.GammaK high-symmetry path.
Gray lines represent negligible-polar phonon modes,
while colored lines indicate strong-polar phonon modes.
(b) Magnified view of the boxed region in (a).
The orange dashed lines mark the phonon wavevectors involved in Raman scattering
with incident light along the z- and y-directions.
]
)<raman>
// TODO: 画一个模拟的图,与实验图对比。
// 实验与计算基本相符。对于声子频率,计算总是低估大约 3%。
// 此外,一些较强的模式在预测无法看到的偏振中也可以看到。例如,一些在 xy 偏振中不应该看到的模式可以被看到了。
// 这个现象可以由 4度的斜切所解释我们将材料略微踮起一些角度就可以使得该模式减小。
// 这个现象也可以由材料或偏振片的微小角度来解释。
// 例如,我们将偏振方向转动 5 度,就可以得到这个模拟结果。
// 此外,由于使用的材料是沿着 c 轴切片的,所以我们在测量 y 入射时不得不将片子以略小于 90 度(约 75 度)的角度放置。这也导致实验与计算的偏差。
// TODO: 翻译成英文
=== Strong-polar Phonons
// 在半导体的极性声子模式中,原子间存在长距离的库伦相互作用,导致散射谱在 Gamma 附近不再连续(引用),如图中的彩色线所示。
// 这导致不同方向的入射/散射光的声子模式不同。
// 具体来说,当入射光/散射光沿着 z 方向时,起作用的是 A-Gamma 线上的声子模式(图中的左半边的橘线),它们适用于群 C6v。
// 这时会有一个 E1 模式TO振动方向在面内和一个 A1 模式LO沿 z 振动)。
// 而当沿着 y 方向入射时,起作用的是 Gamma-K 线上的声子模式(图中的右半边的橘线),它们不再适用于群 C6v而只适用于群 C2v
// 它会分裂成沿x、y、z 方向的三个声子模式(图中的右半边的蓝线),它们分别对应于群 C2v 的 A1、B1 和 B2 表示 TODO: 确认这个几个表示的名字。
// 若考虑到到入射光不是严格沿着 z 方向,而是有一个小的角度(例如 10 度),则此时有一个声子模式沿着 x 方向,另外两个声子模式则为 y-z 两个方向的混合。
#page(flipped: true)[
#figure({
// 使用 m2 m3
let m(n, content) = table.cell(colspan: n, content);
let A1 = [A#sub[1]];
let A2 = [A#sub[2]];
let B1 = [B#sub[1]];
let B2 = [B#sub[2]];
let E1 = [E#sub[1]];
let E2 = [E#sub[2]];
let NA = [Not Applicable]
let yzmix = [y-z mixed#linebreak() (LO-TO mixed)];
let lopc = [Yes#linebreak() (LOPC)];
let overf = [Yes#linebreak() (overfocused)];
table(columns: 20, align: center + horizon, inset: (x: 3pt, y: 5pt),
[*Direction of Incident & Scattered Light*], m(5)[z], m(5)[y], m(9)[between z and y, 10#sym.degree to z],
// z y 45 y&z
[*Number of Phonon*], [1], [2], m(3)[3], m(3)[1], [2], [3], m(4)[1], [2], m(4)[3],
[*Vibration Direction*],
[x#linebreak() (TO)], [y#linebreak() (TO)], m(3)[z (LO)], // z
m(3)[z (TO)], [x#linebreak() (TO)], [y (LO)], // y
m(4, yzmix), [x#linebreak() (TO)], m(4, yzmix), // 45 y&z
[*Representation in Group C#sub[6v]*], m(2, E1), m(3, A1), m(14, NA),
// z y 45 y&z
[*Representation in Group C#sub[2v]*], B2, B1, m(3, A1), m(3, A1), B2, B1, m(4, NA), B2, m(4, NA),
[*Scattering in Polarization*],
[xz], [yz], [xx], [yy], [zz], // z
[xx], [yy], [zz], [xz], [yz], // y
[xx], [yy], [yz], [zz], [xz], [xx], [yy], [yz], [zz], // 45 y&z
[*Raman Intensity (a.u.)*],
m(2)[53.52], m(2)[58.26], [464.69], // z
m(2)[58.26], [454.09], [53.52], [53.55], // y
m(2)[53.71], [3.20], [425.98], [53.56], m(2)[3.60], [50.36], [27.99], // 45 y&z
[*Visible in Common Raman Experiment*],
m(2)[Yes], m(2, lopc), [No], // z
overf, [No], overf, [Yes], lopc, // y
m(4)[???], [???], m(4)[???], // 45 y&z
[*Wavenumber (Simulation) (cm#super[-1])*],
// z y 45 y&z
m(2)[776.57], m(3)[933.80], m(3)[761.80], [776.57], [941.33], m(4)[762.76], [776.57], m(4)[940.86],
[*Electrical Polarity*], m(19)[Strong]
)},
caption: [Strong-polarized phonons near $Gamma$ point],
)
]
// TODO: 这句话放哪里?
// whose dispersion curves exhibit discontinuity near the #sym.Gamma point (also shown in @phonon),
#bibliography("./ref.bib", title: "Reference", style: "american-physics-society")