Raman谱研究不同缓冲层结构对Si_(1-x)Ge_x应力弛豫的影响

应用Raman散射谱研究超高真空化学气相淀积(UHV/CVD)生长的不同结构缓冲层对恒定组分上表层Si_(1-x)Ge_x层应力弛豫的影响。Raman散射的峰位不仅与Ge组分有关,而且与其中的应力状态有关。在完全应变和完全弛豫的情况下，Si_(1-x)Ge_x层中的Si-Si振动模式相对于衬底的偏移都与Ge组分成线性关系。根据实测的Raman峰位，估算了应力弛豫。结果表明

分子束外延低温生长GaAs的Raman光谱研究

对从GaAs衬底剥离下来的低温下分子束外延生长的GaAs(LTG-GaAs)薄膜进行了喇曼光谱测量，研究了不同温度下生长的LTG-GaAs在退火前后晶体完整性的变化。首次观测到了190℃生长样品中As沉淀物所引起的喇曼峰，并证明800℃快速热退火30秒后产生的As沉淀物是无定形As。

ZnSe-ZnTe应变层超晶格的Raman光谱研究

于2010-11-23批量导入

Raman scattering and infrared absorption of silicon nanocrystals in silicon oxide matrix

Structural dependence on annealing of a-SiOx:H was studied by using infrared absorption and Raman scattering. The appearance of Raman peaks in the range of 513-519cm(-1) after 1170 degreesC annealing was interpreted as the formation nanocrystalline silicon with the sizes from 3-10nm. The Raman spectra also show the existence of amorphous-like silicon phase, which is associated with Si-Si bond re-construction at boundaries of silicon nanocrystallites. The presence of the shoulder at 980cm(-1) of Si-O-Si stretching vibration at 1085cm(-1) in infrared spectra imply that except that SiO2 phase, there is silicon sub-oxide phase in the films annealed at 1170 degreesC. This sub-oxide phase is located at the interface between Si crystallites and SiO2, and thus support the shell model for the mixed structures of Si grains and SiO2 matrix.

Observation of the resonant Raman behavior of individual single-walled carbon nanotubes

The different resonant Raman scattering process of single-walled carbon nanotubes (SWNTs) has been found between the Stokes and anti-Stokes sides of the radial breathing modes (RBMs), and this provides strong evidence that Raman spectra of some special diametric SWNTs are in resonance with their electronic transitions between the singularities in the one-dimensional electronic density of states in the valence and conduction bands, and other SWNTs axe beyond the resonant condition. Because of the coexistence of resonant and non-resonant Raman scattering processes for different diametric SWNTs, the relative intensity of each RBM does not reflect the proportion of a particular SWNT.

Effect of rapid thermal annealing on the Raman spectrum of Si0.33Ge0.67/Si (100) alloy

The effect of thermal annealing on the Raman spectrum of Si0.33Ge0.67 alloy grown on Si (100) by molecular beam epitaxy is investigated in the temperature range of 550-800 degrees C. For annealing below 700 degrees C, interdiffusion at the interface is negligible and the residual strain plays the dominant role in the Raman shift. The strain-shift coefficients for Si-Ge and Ge-Ge phonon modes are determined to be 915 +/- 215 cm(-1) and 732 +/- 117 cm(-1), respectively. For higher temperature annealing, interdiffusion is significant and strongly affects the Raman shift and the spectral shape.

Raman study on residual strains in thin 3C-SiC epitaxial layers grown on Si(001)

Raman scattering measurement has been used to study the residual strains in the thin 3C-SiC/Si(001) epilayers with a variation of film thickness from 0.1 to 1.2 mu m. which were prepared by chemical vapor deposition (CVD)growth. Two methods have been exploited to figure our the residual strains and the exact LO bands. The final analyzing results show that residual strains exist in the 3C-SiC epilayers. The average stress is 1.3010 GPa, and the relative change of the lattice constant is 1.36 parts per thousand. Our measurements also show that 3C-SiC phonons are detectable even for the samples with film thickness in the range of 0.1 to 0.2 mu m. (C) 2000 Published by Elsevier Science S.A. All rights reserved.

Electronic and vibrational Raman scattering in resonance with yellow luminescence transitions in GaN on sapphire substrate

We analyze low-temperature Raman and photoluminescence spectra of MBE-grown GaN layers on sapphire. Strong and sharp Raman peaks are observed in the low frequency region. These peaks, which are enhanced by excitation in resonance with yellow luminescence transitions, are attributed to electronic transitions related to shallow donor levels in hexagonal GaN. It is proposed that a low frequency Raman peak at 11.7 meV is caused by a pseudo-local vibration mode related to defects involved in yellow luminescence transitions. The dependence of the photoluminescence spectra on temperature gives additional information about the residual impurities in these GaN layers.

Raman Spectroscopy of Irradiation Effect in Three Carbon Allotropes Induced by Low Energy B Ions

Irradiation efect in three carbon allotropes C60, diamond and highly oriented pyrolytic graphite (HOPG) induced by 170 keV B ions, mainly including the process of the damage creation, is investigated by means of Raman spectroscopy technique. The diferences on irradiation sensitivity and structural stability for C60, HOPG and diamond are compared. The analysis results indicate that C60 is the most sensitive for B ions irradiation,diamond is the second one and the structure of HOPG is the most stable under B ion irradiation. The damage cross sections ? of C60, diamond and HOPG deduced from the Raman spectra are 7.78×10−15 , 6.38×10−15 and1.31 × 10−15cm2, respectively.

1.23GeV Fe离子在C_(60)薄膜中形成潜径迹的Raman谱分析

用能量为1.23GeV的快Fe离子辐照了多层堆叠的C60薄膜。用Raman散射技术分析了快Fe离子在C60薄膜中由强电子激发引起的效应,主要包括辐照引起C60分子的聚合及其高温、高压相(HTHP)的形成,和在髙电子能损下C60晶体点阵位置上的C60分子向非晶碳的转变。由此演绎出了快Fe离子在C60薄膜中的损伤截面或潜径迹截面σ和潜径迹的半径Re,及其随沉积在电子系统中的能量密度的变化而变化的规律。

Raman spectroscopy of apatite irradiated with swift heavy ions with and without simultaneous exertion of high pressure

Durango apatite was irradiated with energetic U ions of 2.64 GeV and Kr ions of 2.1 GeV, with and without simultaneous exposure to a pressure of 10.5 GPa. Analysis by confocal Raman spectroscopy gives evidence of vibrational changes being marginal for fluences below 5x10(11) ions/cm(2) but becoming dominant when increasing the fluence to 8x10(12) ions/cm(2). Samples irradiated with U ions experience severe strain resulting in crystal cracking and finally breakage at high fluences. These radiation effects are directly linked to the formation of amorphous tracks and the fraction of amorphized material increasing with fluence. Raman spectroscopy of pressurized irradiated samples shows small shifts of the band positions with decreasing pressure but without a significant change of the Gruneisen parameter. Compared to irradiations at ambient conditions, the Raman spectra of apatite irradiated at 10.5 GPa exhibit fewer modifications, suggesting a higher radiation stability of the lattice by the pressure applied.

Raman investigation of ion-implanted ZnO films

ZnO thin films were implanted at room temperature with 80 keV N+ or 400 keV Xe+ ions. The implantation fluences of N+ and Xe+ ranged from 5.0 x 10(14) to 1.0 x 10(17)/cm(2), and from 2.0 x 10(14) to 5.0 x 10(15)/cm(2), respectively. The samples were analyzed using Raman spectroscopy and the Raman scattering modes of the N- and Xe-ion implanted samples varying with implantation fluences were investigated. It was found that Raman peaks (bands) at 130 and 578 cm(-1) appeared in the spectra of ion-implanted ZnO samples, which are independent of the ion species, whereas a new peak at 274 cm(-1) was found only in N-ion implanted samples, and Raman band at 470 cm(-1) was found clearly in Xe-ion implanted samples. The relative intensity (peak area) increased with the increasing of the implantation fluences. From the comparison of the Raman spectra of N- and Xe-ion implanted ZnO samples and considering the damage induced by the ions, we analyzed the origin of the observed new Raman peaks (bands) and discussed the structure changes of ZnO films induced by N- and Xe-ion implantations.