79 lines
5.6 KiB
XML
79 lines
5.6 KiB
XML
4H-SiC 是一种具有优良性质的半导体材料，包括宽禁带、高临界电场强度、高热导率和沿 c 轴的高电子迁移率，因此受到了广泛的研究。
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受益于外延技术的发展和新能源产业的需求增长，4H-SiC 在功率电子器件中得到了广泛应用。
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然而，4H-SiC 器件的性能仍然受到缺陷的限制，如何在生长和工作条件下避免缺陷的产生仍然是一个挑战。
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此外，用于表征 SiC 掺杂的方案（如二次离子质谱（SIMS）和霍尔效应测量）通常是破坏性的且耗时，因此迫切需要开发原位和非破坏性的表征技术。
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// 随着尺寸缩小，4H-SiC 中的缺陷对器件性能的影响更加显著。（纳米材料？
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The 4H-silicon carbide (SiC) has long attracted a lot of research
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thanks to its wider bandgap, higher critical electric field strength,
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higher thermal conductivity, and higher electron mobility along the c-axis
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than silicon (Si) and gallium arsenide (GaAs) as well as other SiC polytypes
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@casady_status_1996 @okumura_present_2006.
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It has been widely used in power electronic devices
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thanks to the development of epitaxy technology and the increasing application in the new energy industry
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@tsuchida_recent_2018 @harada_suppression_2022 @sun_selection_2022.
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However, the performance of 4H-SiC devices remains constrained by the presence of defects,
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which may be introduced during the growth process @nishio_triangular_2020 @demenet_tem_2005
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or arise under device operating conditions
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@mahadik_ultraviolet_2012 @okada_dependences_2018 @iwahashi_extension_2017 @caldwell_driving_2010
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@miyanagi_annealing_2006 @iijima_correlation_2017.
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Furthermore,
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conventional methods for characterizing the doping properties of SiC
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(such as secondary ion mass spectrometry (SIMS) @kudriavtsev_quantitative_2003 @kim_characteristics_2024
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and Hall effect measurements @noguchi_comparative_2021 @asada_hall_2016),
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are destructive and time-consuming.
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Therefore, there is a pressing need to develop an in-situ and non-destructive characterization techniques.
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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。
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声子可以通过多种实验技术来探测，包括 EELS、IR 吸收谱等。
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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。
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早有关于拉曼的研究，且拉曼已被广泛用于区分 SiC 的多型。
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Phonons (quantized atomic vibrations) play a fundamental role
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in understanding the atomic structure as well as the thermal and electrical properties of semiconductors.
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They could be probed by various experimental techniques,
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such as electron energy loss spectroscopy @yan_single-defect_2021 @egoavil_atomic_2014
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and infrared absorption spectroscopy @pluchery_infrared_2012 @tong_temperature-dependent_2018.
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Among these techniques,
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Raman spectroscopy is the most commonly used method,
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// TODO: 增加一些引用，可以先不用收集文献给这里，最后把其它部分的全拿过来就行了。
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as it provides non-destructive, non-contact, rapid and spatially localized measurement of phonons
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that near the #sym.Gamma point in reciprocal space.
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Studies in Raman scattering of 4H-SiC have been conducted since as early as 1968 @feldman_phonon_1968
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and nowadays have been widely employed to identification of different SiC polytypes
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@guo_characterization_2012 @yan_study_2016 @hundhausen_characterization_2008 @nakashima_raman_2013.
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近年来，更多信息被从拉曼光谱中挖掘出来。
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LO 声子峰或 LOPC 峰已经被证明与自由载流子的类型和浓度有关，它们已经被用于估计离子注入层的厚度和 n 型 SiC 的掺杂浓度。
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部分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。
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也有一些研究探讨了掺杂对拉曼光谱的影响。 // TODO: 具体是什么影响？
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然而，拉曼光谱上仍有一些不知来源的峰；同时，也缺少一些理论上预测应该存在的峰。
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此外，预测掺杂导致的新峰也没有说明原因。
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In recent years, increasingly rich information has been extracted from Raman spectra of 4H-SiC.
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Longitudinal optical phonon–plasmon coupling (LOPC) peek
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has been utilized to rapidly estimate to identify doping type in different layers
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// depth profiling xxx
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and the doping concentration in n-type SiC.
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// Raman scattering from anisotropic LO-phonon-plasmo
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Peeks associated with some stacking faults have also been investigated
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and used to detect the presence and location of specific structural faults.
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// TODO: 缺陷峰，并补充对应的文献
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Moreover, the potential effects of doping on Raman spectra have been explored.
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// TODO: 掺杂导致的本征峰的变化的文献
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However, there are still some unsolved issues.
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Certain phonon modes predicted by theory remain unobserved,
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while there are still some unidentified peaks in the Raman spectra.
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An A1 peek was observed in some experiment but not in others, the reason for which is still unclear.
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In addition, relation between defects and Raman peek is still not very clear,
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potential raman peeks caused by defects and doping still need to be explored.
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// TODO: 调整语言，细化描述
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In this paper, we explored the phonon in 4H-SiC by three ways:
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symmetry analysis, first-principles calculations, and Raman experiment.
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We first investigated the phonon modes in perfect 4H-SiC,
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and then explored the phonon modes associated with defects and doping.
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// TODO: 描述自己做了什么，强调自己是第一次做到了什么。
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