注碳GaN的拉曼散射谱研究

本文研究了离子注入碳的GaN材料的Raman光谱。观察到离子注入碳的GaN在800℃退火后其拉曼光谱在1350和1600cm-1处出现两个峰。分析指出它们很可能分别来自GaN的CN和C=C局域伸缩振动。     

离子注入法制备GaN∶Er薄膜的Raman光谱分析

对离子注入法制备的u-,n-和p-GaN∶Er三种类型的薄膜样品进行了Raman光谱分析。Er+注入GaN样品后新出现了293,362和670 cm-1等波数的Raman峰,其中293 cm-1处的Raman峰被指认为无序激活的Raman散射(DARS),362 cm-1和670 cm-1处的Raman峰可能与离子注入后形成的GaN晶格缺陷有关。上述GaN∶Er样品在800℃退火前后的E₂(high)特征峰均向高频方向移动,表明薄膜晶格中均存在着压应力。采用洛伦兹拟合分析了Raman光谱中组成A₁(LO)模式峰的未耦合LO模与等离子体激元耦合模LPP+在不同样品中的出现情况,定性指出了GaN∶Er系列样品中载流子浓度的变化规律。     

GaN和GaN:Mg外延膜低温拉曼谱的对比研究

对液氮温度下六方相GaN和掺Mg的P型GaN薄膜的拉曼谱进行了对比研究。除对两个样品中主晶格振动模进行了对比分析外,着重讨论了位于247 cm-1的散射峰的产生机制。结果表明GaN:Mg的谱中该峰的散射强度随温度升高先增大再减小,在500K以上消失且对样品重新降温到78K观察此峰不再出现,因此认为它是缺陷产生的振动模。而GaN样品中经同样加热降温的过程此峰仍然存在,说明两个样品中该峰的产生机制不同。此外,在GaN:Mg的谱中还观察到Mg诱导的局域振动模。     

注氦尖晶石的红外光谱研究

利用傅立叶变换红外光谱仪对注He尖晶石样品随退火温变化而引起光吸收性能的变化进行了研究。 发现尖晶石样品在626.4 cm-1附近的吸收峰随注入剂量的增加向小波数方向移动, 而在随后退火过程该吸收峰随退火温度的增加而向大波数方向回复。 该吸收峰的回复行为依赖于注入剂量和退火温度。 认为在626.4 cm-1附近吸收峰随注入剂量和退火温度的这种变化与尖晶石中He的俘获以及释放有关。 The infrared absorption behavior of helium implanted spinel with annealing temperature was studied by Fourier transformed infrared (FTIR) spectroscopy. It was found that the absorbance peak at 626.4 cm-1 shifted to smaller wave numbers with the increase of implantation fluence, while on subsequent annealing the absorbance peak shifted back to larger wave numbers with the increase of annealing temperature. The shift of the peak at 626.4 cm-1 with He implantation/annealing is considered to be related with the trapping and release of helium atoms in lattice sites in the spinel crystal.     

Si/SiGe异质结构的硅盖层中应变对Raman谱特征的影响

应变Si/SiGe异质结构通过大剂量Ge离子注入并结合高温快速热退火制备而成。325 nm波长的紫外激光被用于调查应变Si盖层的Raman谱特征。实验发现,硅盖层中的张应变导致硅的520 cm-1的一级拉曼散射峰向低频方向偏移,峰的偏移程度反映硅盖层中横向张应力的大小约为12.5×108 N·m-2。硅盖层中的张应变并未导致1 555和2 330 cm-1的次级拉曼散射峰的变化。     

注入Si中的稀土离子Er3+的光学特性

用离子注入方法,将稀土离子Er3+注入到n-Si单晶中,通过对其低温(77K)光致发光光谱的测量,研究其光学特性.结果表明,注入剂量控制在1×1012cm-2～1×1015cm-2范围,退火温度控制在900℃～1100℃时,样品的主要发光峰值位于1.54μm左右.研究了样品的光致发光光谱随注入剂量、退火温度的变化关系,给出峰值在1.54μm附近的未分辨开的谱线的半宽为16.4meV.     

Kr离子注入SiC的拉曼光谱研究

应用拉曼光谱研究了5 MeV Kr离子（注量分别为5×1013,2×1014,1×1015 ions/cm2）室温注入6H SiC单晶及其高温退火处理后结构的变化。 研究表明, 注入样品的拉曼光谱中不仅出现了Si—C振动的散射峰, 还产生了同核Si—Si键和C—C键散射峰。 Si—C散射峰强度随退火温度升高而增强, 当退火温度高达1000 ℃时, 已接近未辐照SiC的散射峰强度。晶体Si—Si键散射峰强度随退火温度变化不大, 而非晶Si—Si键散射峰强度随退火温度的增加逐渐消失。相对拉曼强度（Relative Raman Intensity, 简称RRI）随注量的增加逐渐减小并趋于饱和, 且不同退火温度样品的饱和注量不相同; RRI随退火温度的增加逐渐升高, 这在低注量样品中表现得尤为明显。 低、中、高3种注量样品的RRI随退火温度的增加从重合逐渐分离, 并且退火温度越高, 分离越大。 Raman spectroscopy was used to study the structure changes of 6H SiC single crystal implanted with 5 MeV Kr (Krypton) at room temperature and subsequently annealed at high temperature. The Raman spectrum of the implanted SiC displays not only Si—C bonds vibration peaks, but also homonuclear Si—Si and C—C bond vibration peaks. Si—C bond vibration peaks gradually strengthen with increasing temperature. When annealing at 1000 ℃, the peak intensity of Raman spectrum is close to that of virgin specimen. It is found that crystal Si—Si bond vibration peaks do not change when annealing, but amorphous Si—Si bond vibration peaks disappear with increasing annealing temperature. The Relative Raman Intensity (RRI) values decrease with increasing fluence and tend to saturate, but the saturation fluences is different for various anneal temperature. The RRI values increases with raising annealing temperature, which is more obvious in low implanted specimens. At the same time, the RRI values separate gradually with increasing temperature and this phenomenon is strengthened by annealing temperature.     

气相外延GaN的拉曼散射

测量了在蓝宝石衬底上气相外延生长GaN的拉曼散射谱.除观察到已被确认的两个E2,一个A1(TO)和一个E1(TO)声于振动以外,在734±3cm-1处观察到一个散射峰且从实验上确认其为GaN的纵向光学声子模E1(LO).而且发现其强度与外延层晶体质量密切相关.A1(TO)和高频E2散射峰相对强度变化显示不同生长条件引起的外延层质量的变化.     

离子注入对InAs/GaAs量子点光学效质的影响

研究了低能质子注入诱导的界面混合和快速热退火对量子点发光效率的影响，对其光致发光 峰强进行了拟合计算.研究发现量子点的发光峰强度主要由载流子俘获时间和非辐射复合寿 命决定.由于后退火处理能够部分的消除因质子注入造成的缺陷，量子点中非辐射复合中心 浓度与注入剂量成亚线性关系；退火温度越高，非辐射复合中心被消除越多，亚线性程度越 高.界面混合导致的俘获效率的增加和注入损伤引起的非辐射复合是相互竞争过程，存在一 个临界的注入剂量N_C，当注入剂量N小于N_C，界面混合作 用较为明显，量子点 发光峰强随注入剂量增加而增强；当N大于N_C时，质子注入引起了大量的非 辐射复合 中心，主要表现为注入损伤，量子点的发光峰强随注入剂量增加而迅速减弱.退火温度越高 ，N_C越大. 关键词： 量子点 离子注入 峰强     

磷离子注入速率对4H-SiC(0001)晶格恢复与电阻率降低的影响

高剂量的磷离子注入4H-SiC(0001)晶面，注入速率从1.0×1012到4.0×1012 P+ cm-2s-1变化，而注入剂量固定为2.0×1015 P+ cm-2。室温注入，1500oC的高温下退火。利用光荧光和拉曼谱分析注入产生的晶格损伤以及退火后的残余缺陷。通过霍耳测试来分析注入层的电学性质。基于上述测试结果，发现通过减小磷离子的注入速率，极大地减少了注入层的损伤及缺陷。考虑到室温注入以及相对较低的退火温度(1500 oC)，在注入速率为1.0×1012 P+ cm-2s-1及施主浓度下为4.4×1019 cm-3的条件下，获得了非常低的方块电阻106 Ω/sq。     

Optical spectroscopy study of damage evolution in 6H-SiC by H_2~+ implantation

Lattice defects induced by ion implantation into Si C have been widely investigated in the decades by various techniques. One of the non-destructive techniques suitable to study the lattice defects in Si C is the optical characterization. In this work, confocal Raman scattering spectroscopy and photoluminescence spectrum have been used to study the effects of 134-ke V H_2~+ implantation and thermal treatment in the microstructure of 6 H-Si C single crystal. The radiation-induced changes in the microstructure were assessed by integrating Raman-scattering peaks intensity and considering the asymmetry of Raman-scattering peaks. The integrated intensities of Raman scattering spectroscopy and photoluminescence spectrum decrease with increasing the fluence. The recovery of the optical intensities depends on the combination of the implantation temperature and the annealing temperature with the thermal treatment from 700℃ to 1100℃. The different characterizations of Raman scattering spectroscopy and photoluminescence spectrum are compared and discussed in this study.     

MOCVD生长的GaN和GaN:Mg薄膜的拉曼散射

通过显微拉曼散射对用金属有机化学气相沉积(MOCVD)法在Al2O3衬底上生长的六方相CaN和掺Mg的P型GaN薄膜进行了研究。在两个样品的拉曼散射谱中同时观察到位于640,660cm^-1附近的两个峰。640cm^-1的峰归因于布里渊区边界(L点)最高声学声子的二倍频,而660cm^-1的峰为布里渊区边界的光学声子支或缺陷诱导的局域振动模。掺Mg的GaN在该处的峰型变宽是Mg诱导的缺陷引起的加宽或Mg的局域模与上述两峰叠加的结果。在掺Mg的样品中还观察到276,376cm^-1几个局域模并给予了解释。同时掺Mg的GaN中出现了应力弛豫的现象,掺Mg引起的失配位错和电子-声子相互作用都有可能对E2模的频率产生影响。     

LiTaO3的高温拉曼光谱研究

利用显微共聚焦拉曼光谱技术研究了LiTaO3晶体在298～948K温度范围内的拉曼光谱,通过对其高波数拉曼峰的分析,研究了LiTaO3的相变机制。研究发现,除466.7cm-1峰外,LiTaO3的其余拉曼峰随着温度的升高向低波数方向明显频移;所有拉曼峰的半高宽随着温度的升高逐渐增加,同时拉曼峰的强度逐渐减弱;在933K附近,LiTaO3的三个拉曼峰的消失,表明LiTaO3发生了从低温铁电相到高温顺电相的相变;与此同时,在该温度附近,359.5,385.0以及466.7cm-1峰的半高宽存在超线性增加。研究结果表明,LiTaO3从低温铁电相到高温顺电相的相变是一种混合型相变,其相变过程可逆。     

新型Hg系高Tc超导体(Hg_(0.8)Mo_(0.2))Sr_2(Y_(1-x)Ca_x)Cu_2O_(6+δ)的拉曼光谱

新型Ｈｇ系高Ｔｃ超导体（Ｈｇ０．８Ｍｏ０．２）Ｓｒ２（Ｙ１－ｘＣａｘ）Ｃｕ２Ｏ６＋δ的拉曼光谱许存义左健冯建平（中国科学技术大学结构分析开放实验室合肥２３００２６）吴若（江西师范大学物理系南昌３３００２７）ＲａｍａｎＳｐｅｃｔｒａｏｆｔｈｅＮｅｗＳｅ...     

掺Er/Er+O的GaN薄膜光学性质的研究

利用Raman散射谱研究了GaN注Er以及Er+O共注样品的振动模，并讨论了共注入O对Er离子发光的影响. 在Raman散射谱中，对于注Er的GaN样品出现了300 cm^-1和670 cm^-1两个新的Raman峰，而对于Er+O共注样品，除了上述两个峰外，在360 cm^-1处出现了另外一个新的峰，其中300 cm^-1峰可以用disorder-activated Raman scattering (DARS)来解释，670 cm^-1峰是由于与N空位相关的缺陷引起的，而360 cm^-1峰是由O注入引起的缺陷络合物产生的. 由于360 cm^-1模的缺陷出现，从而导致Er+O共注入GaN薄膜红外光致发光(PL)强度的下降. 关键词： GaN Er Raman散射 光致发光     

Structural modifications of GaN after cerium implantation

Among the family of rare earth (RE) dopants, the doping of first member Ce into GaN is the least studied system. This article reports structure properties of Ce‐doped GaN realized by technique of ion implantation. Ce ions were implanted into metal organic chemical vapor deposition grown n‐ and p‐GaN/sapphire thin films at doses 3 × 10¹⁴ and 2 × 10¹⁵ cm⁻². X‐ray diffraction scans and Raman scattering measurements exhibited expansion of lattice in the implanted portion of the samples. First order Raman scattering spectra show appearance of several disorder‐activated Raman scattering modes in addition to typical GaN features. A dose‐dependent decrease in intensity of E₂ mode was observed in Raman the spectra of the implanted samples. Ultraviolet Raman spectra of implanted samples show complete quenching of photoluminescence emission and appearance of multiple A₁(LO) phonon scattering modes up to fifth order. Moreover, a decrease in intensity and an increase in line width of LO modes as a function of wavenumber were observed for implanted samples. Copyright © 2012 John Wiley & Sons, Ltd.     

C and Si ion implantation and the origins of yellow luminescence in GaN

We have studied the influence of C and Si ion implantation with different implantation doses on yellow luminescence (YL) from GaN. Three kinds of GaN samples were used. In their as-grown states, #1 samples had strong YL, #2 samples had no YL, while #3 samples had weak YL. Our experimental results show that: (i) after annealing at 950 °C, the YL intensity for Si ion implanted #1 sample decreased with increasing implantation dose, while that for C ion implanted #1 sample exhibited a reverse rule; (ii) for #2 samples, C ion implantation produced much stronger YL than Si ion implantation did after annealing at 950 °C; (iii) the YL intensity sequence for Si ion implanted and 950 °C annealed #1, #2, and #3 samples was consistent with that for the unimplanted #1, #2, and #3 samples. However, the YL intensity sequence for the C ion implanted and 950 °C annealed #1, #2, and #3 samples reversed with that for the unimplanted ones. In order to explain all these phenomena, we suggested a physical model which claims that the deep C center is another important origin of YL in GaN, and during C ion implantation, the C ion prefers to combine with a V_Ga to form a C_Ga. PACS 78.55.-m, 85.40.Ry, 68.55.Ln     

胃炎和胃溃疡组织细胞的显微拉曼光谱研究

利用共焦显微拉曼光谱研究了胃炎组织和胃溃疡组织的粘膜细胞。结果表明,与胃炎组织细胞比较,溃疡组织细胞中胞嘧啶的振动峰781 cm-1相对较弱,而腺嘌呤和胸腺嘧啶793,823cm-1处的峰强有所增加; 对应于α螺旋结构蛋白质酰胺Ⅰ和酰胺Ⅲ带的1654和1230～1270cm-1的强度均相对减小,色氨酸特征峰1332cm-1和苯丙氨酸特征峰1003cm-1强度有所降低,同时与色氨酸残基微环境变化密切相关的1554频移到1556cm-1,且强度有所增加;脂类的特征谱线1073 cm-1向高波数频移到了1078cm-1, 对应于CH₂扭转振动的1303cm-1与来自于CH面内变形振动的1268cm-1强度比值减小。上述变化表明两种疾病组织细胞中的核酸,蛋白质和脂类在成分、结构和构型上都存在明显差异;研究发现利用C—H弯曲振动的谱线1449cm-1和蛋白质酰胺Ⅲ带的谱线1660cm-1的强度比值A₁₄₄₉/A₁₆₆₀区分两种疾病具有较好的准确性。     

离子注入ZnO薄膜的拉曼光谱研究

室温下,用80 keV N⁺和400 keV Xe⁺离子注入ZnO薄膜,注入剂量分别为5.0×10¹⁴—1.0×10¹⁷/cm²和2.0×10¹⁴—5.0×10¹⁵/cm².利用拉曼散射技术对注入前后的ZnO薄膜进行光谱测量和分析,研究了样品的拉曼光谱随离子注入剂量的变化规律.实验结果发现,未进行离子注入的样品在99,435 cm<     

Au5+ ion implantation induced structural phase transitions probed through structural,microstructural and phonon properties in BiFeO3 ceramics,using synergistic ion beam energy

Implanted Au⁵⁺-ion-induced modification in structural and phonon properties of phase pure BiFeO₃ (BFO) ceramics prepared by sol–gel method was investigated. These BFO samples were implanted by 15.8?MeV ions of Au⁵⁺ at various ion fluence ranging from 1?×?10¹⁴ to 5?×?10¹⁵?ions/cm². Effect of Au⁵⁺ ions’ implantation is explained in terms of structural phase transition coupled with amorphization/recrystallization due to ion implantation probed through XRD, SEM, EDX and Raman spectroscopy. XRD patterns show broad diffuse contributions due to amorphization in implanted samples. SEM images show grains collapsing and mounds’ formation over the surface due to mass transport. The peaks of the Raman spectra were broadened and also the peak intensities were decreased for the samples irradiated with 15.8?MeV Au⁵⁺ ions at a fluence of 5?×?10¹⁵?ion/cm². The percentage increase/decrease in amorphization and recrystallization has been estimated from Raman and XRD data, which support the synergistic effects being operative due to comparable nuclear and electronic energy losses at 15.8?MeV Au⁵⁺ ion implantation. Effect of thermal treatment on implanted samples is also probed and discussed.