共查询到18条相似文献,搜索用时 62 毫秒
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研究了利用离子注入法得到的掺氮n-SiC拉曼光谱. 理论线形分析表明,与4H-SiC相比,6H-SiC中LO声子等离子体激元耦合模(LOPC模)拉曼位移随自由载流子浓度变化较小. 5145nm激发光下得到的电子拉曼散射光谱表明,k位处由1s(A1)到1s(E)的能谷轨道跃迁带来的拉曼谱6H-SiC中有四条,4H-SiC中有二条;高频6303及635cm-1处观察到的谱线被认为与深能级缺陷有关. 最后,利用纤锌矿型结构二级拉曼散射选择定则指认了6
关键词:
碳化硅
电子拉曼散射
轨道能谷分裂
倍频谱 相似文献
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用拉曼散射光谱估算纳米Ge晶粒平均尺寸 总被引:4,自引:1,他引:3
用射频共溅射技术和真空退火方法制备了埋入SiO2基底中的纳米Ge复合膜(nc-Ge/SiO2)测量了不同温度退火后该复合膜的拉曼散射光谱,其结果与晶体Ge的拉曼谱相比,纳米Ge的拉曼峰红移峰形变宽,用拉曼谱的参数计算了纳米Ge晶粒的平均尺寸,所得结果与声子限域理论模型符合。 相似文献
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采用分子束外延(MBE)方法在BaF2(111)衬底上生长了高质量的PbTe单晶薄膜, 拉曼光谱测量观察到了表面氧化物的振动模、布里渊区中心(q≈0)纵光学(LO)声子振动模以 及声子-等离子激元耦合模振动.随着显微拉曼光谱仪激光光斑聚焦深度的改变,各拉曼散射 峰的峰位、积分强度、半高宽等都表现出不同的变化趋势. 随着激光光斑聚焦位置从样品表 面上方3μm处变化到表面下方3μm处,PbTe外延薄膜的LO声子频率从119cm-1移 动到124cm-1
关键词:
PbTe外延薄膜
拉曼散射
纵光学声子 相似文献
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当酒精的弱增益拉曼模式处于罗丹明640染料分子的激光增益范围时,在由悬垂液滴构成的圆形谐振腔中,观察到乙醇分子C—H伸缩系列模中多个弱增益拉曼模式的受激拉曼散射(SRS)光谱.随着抽运光的增强,迅速增长的强增益拉曼模式的受激辐射抑制了其他弱增益模式的SRS,并导致染料激光的完全淬灭.通过分析圆形腔腔模的光子速率方程和激光染料分子的三能级粒子数速率方程,解释了观察到的实验现象.
关键词:
受激拉曼散射
悬垂液滴
弱拉曼增益模式
激光增益 相似文献
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Zhiyuan Xiao Yanqing Yang Sheng Ouyang Zongde Kou Bin Huang Xian Luo 《Journal of Raman spectroscopy : JRS》2015,46(12):1225-1229
Phonon confinement effect and surface optical mode in SiC nanocrystal have been investigated through Raman spectroscopy. Considering high density of stacking faults in SiC grains, the correlation length of RWL (proposed by Richter, Wang, Li to explain phonon confinement in nano silicon) model is determined as a distance between nearby stacking faults. Thus, homogeneous region becomes thin slices in cylindrical SiC grains, which redefines weighting function. Effect of anisotropy of phonon dispersion curve is also analyzed during calculation. The additional 875‐cm−1 band is attributed to defects and amorphous SiC, which is confirmed by transmission electron microscopy. SiC grains are approximated as column array with grain boundary substances regarded as surrounding medium, which explains surface optical phonon mode at 915 cm−1. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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分别采用532,488 nm可见光和325 nm紫外光激发,对金属有机化学气相沉积法在蓝宝石衬底上生长的六方相InGaN/GaN薄膜样品在室温和78 K低温下的拉曼散射谱进行了研究。在可见光激发时,E2模和A1(LO)模的散射信号主要来自GaN层;采用紫外光激发时,A1(LO)模向低频方向移动且共振增强,此散射信号来自InGaN层。在可见光激发的情况下,在A1(LO)模的高频方向观察到一个宽峰,此宽峰为InGaN的LO声子-等离子激元耦合模,根据耦合模频率得到InGaN层中的电子浓度为ne=1.61×1018 cm-3。紫外光激发时,没有观察到耦合模,A1(LO)模散射信号主要来自样品表面耗尽层,由此估算样品中的耗尽层宽度大约在40 nm。此外,还对比分析了在室温和78 K低温下LO声子-等离子激元耦合模的散射强度的变化规律,计算了不同温度下等离子激元的屏蔽波矢。这些结论对于了解InGaN材料的基本性质以及氮化物光电器件的开发利用都有重要参考价值。 相似文献
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This paper employs micro-Raman technique for detailed analysis of
the defects (both inside and outside) in bulk 4H-SiC. The main peaks
of the first-order Raman spectrum obtained in the centre of defect
agree well with those of perfect bulk 4H-SiC, which indicate that
there is no parasitic polytype in the round pit and the hexagonal
defect. Four electronic Raman scattering peaks from nitrogen defect
levels are observed in the round pit (395\,cm$^{-1}$,
526\,cm$^{-1}$, 572\,cm$^{-1}$, and 635\,cm$^{-1})$, but cannot be
found in the spectra of hexagonal defect. The theoretical analysis
of the longitudinal optical plasmon--phonon coupled mode line shape
indicates the nonuniformity of nitrogen distribution between the
hexagonal defect and the outer area in 4H-SiC. The second-order
Raman features of the defects in bulk 4H-SiC are well-defined using
the selection rules for second-order scattering in wurtzite
structure and compared with that in the free defect zone. 相似文献
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半导体材料的纵光学声子与等离子体激元耦合模(LOPC模)能够提供材料电学方面的相关信息。本文在室温下测得了n型4H-和6H-SiC的拉曼光谱,分析了掺入的杂质对于SiC晶体拉曼光谱的影响,通过拟合n型4H-和6H-SiC晶体的LOPC模的线型得到等离子体频率,并由此从理论上计算了载流子浓度。载流子浓度的理论计算值与霍尔测量的结果符合得很好。研究结果进一步证实了对于n型4H-和6H-SiC晶体,可以通过分析LOPC模的线形来较准确地给出相关材料的载流子浓度。 相似文献
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用X射线衍射(XRD)技术和显微Raman散射方法对金属有机化学气相沉积(MOCVD)法生长的六方相InxGa1-xN薄膜样品进行了研究,观察到了相分离现象和LO声子-等离子耦合模(LPP+),讨论了InxGa1-xN的A1(LO)模被屏蔽的主要物理机制.同时,对Raman谱中E2和A1(TO)声子模进行了分析和讨论.在InxGa1-xN样品的低温Raman谱中还观察到单电子跃迁产生的Raman散射信号.
关键词:
Raman散射
X射线衍射
相分离
应力
LO声子-等离子耦合 相似文献
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Shenghuang LinZhiming Chen Lianbi LiYintu Ba Sujuan LiuMingchao Yang 《Physica B: Condensed Matter》2012,407(4):670-673
The spectra of 6H-SiC crystals including micropipes have been examined for the Si face using Raman scattering. The first-order Raman features reveal that the intensity of the transverse optical phonon band centered at ∼796 cm−1 is sensitive to the micropipes. And the second-order Raman features of the micropipes in bulk 6H-SiC are well-defined using the selection rules for second-order scattering in wurtzite structure. It is found that there are some second-order peaks missing for the micropipe-including sample, which may be induced by the reduction of the incident laser intensity at around the micropipe, especially the uneven surface in the inner wall of the micropipe. These features might also be employed to characterize other structural defects such as screw-dislocations and threading edge dislocations. 相似文献
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CHANG Cheng LI Zheng ZHOU Yinqing 《Chinese Journal of Lasers》2001,10(1):29-33
1 Introduction Peoplefocustheirattentionontheresearchanddevelopmentofopticalfibertemperaturesensorsystemsbecauseofavarietyofadvantages ,suchaseasetoinstalandmaintain,immunitytoelectromagneticinterference (EMI) ,safetyinhazardousenvironments.Thesefeatures… 相似文献