碳化硅中氦离子高温注入引入的缺陷及其退火行为的光谱研究

对氦（He）离子高温（600 K）注入6H-SiC中的辐照缺陷,在阶梯温度退火后演化行为的拉曼光谱和室温光致发光谱的特征进行了分析.这两种方法的实验结果表明,离子注入所产生晶格损伤的程度与注入剂量有关;高温退火导致损伤的恢复,不同注入剂量造成的晶格损伤需要不同的退火温度才可恢复.在阶梯温度退火下呈现出了点缺陷的复合、氦-空位团的产生、氦泡的形核、长大等特性.研究表明：高温（600 K）注入在一定剂量范围内是避免注入层非晶化的一个重要方法,为后续利用氦离子注入空腔掩埋层吸杂或者制备低成本、低缺陷密度的绝缘层 关键词： 6H-SiC 离子注入 拉曼光谱 光致发光谱     

中能高浓度氦离子注入对钨微观结构的影响

采用15 keV, 剂量1×10¹⁷/cm², 温度为600 ℃氦离子注入钨, 分别以块体钨研究氦离子对钨的表面损伤; 以超薄的钨透射电镜样品直接注入氦离子, 研究该条件下钨的微观结构变化, 以了解氦离子与钨的相互作用过程; 采用扫描电子显微镜、聚焦离子束扫描显微镜、透射电子显微镜、高分辨透射电子显微镜等分析手段研究氦离子注入对钨表面显微结构的影响及氦泡在钨微观结构演化中的作用.     

高能离子梯度多剂量辐照4H-SiC的微结构及硬度变化研究

为探讨高温高能离子辐照碳化硅后的结构和力学性能随剂量的变化，应用拉曼光谱和纳米压痕技术研究了122 MeV的20Ne4+离子梯度多剂量辐照后的4H-SiC。研究表明，SiC的相对拉曼强度随剂量的增大呈指数规律下降，并出现了代表无序化Si-C键和同核Si-Si键的散射峰。基于DI/DS模型的初步拟合表明，在低剂量范围内扩展缺陷簇是引起SiC无序化的主要因素，高剂量范围内的无序化则是由离子直接碰撞过程的非晶化和扩展缺陷簇共同引起。辐照后的SiC硬度取决于位错钉扎和共价键断裂的共同作用，在0~4.00 dpa之间硬度随剂量增大而增大，在4.00~8.05 dpa之间硬度随剂量增大而减小，剂量在8.05 dpa时，硬度相比于未辐照区域略高，此时共价键断裂和位错钉扎达到平衡。     

KTN晶体及其熔体结构的高温拉曼光谱研究

测量并研究了不同温度(室温—1573 K)范围内KTN晶体的拉曼光谱及其熔体的高温拉曼光谱,分析了KTN晶体结构随温度变化的规律及其熔体的结构特征.随着温度的升高,KTN晶体的拉曼光谱谱峰都不同程度地向低波数方向移动,同时存在不同程度的展宽,并伴随强度的减弱.观察并解释了温度353 K附近KTN晶体样品的四方—立方转相现象.研究了KTN晶体拉曼光谱中538cm^-1,585cm^-1,835cm^-1和877cm^-1谱峰及其 关键词： 高温拉曼光谱 熔体 KTN晶体     

调幅W(Mo)/Cu纳米多层膜He+离子辐照响应行为

用磁控溅射技术制备不同调幅波长 (L) 的W(Mo)/Cu纳米多层膜,所制膜系在60 keV氦离子 (He⁺) 辐照条件下注入不同剂量: 0, 1×10¹⁷ He⁺/cm², 5×10¹⁷ He⁺/cm². 用X射线衍射仪 (XRD) 和高分辨透射电子显微镜(TEM)表征W(Mo)/Cu纳米多层膜辐照前后微观结构. 研究结果表明: 1) He⁺离子轰击引起温升效应是导致沉积态亚稳相β-W 转变成稳态 α-W相的主因, 而与调幅波长无明确关联; 2) 纳米多层结构中W(Mo) 和Cu膜显现出的辐照耐受性与调幅波长相关, 调幅波长越小, 抗He⁺的辐照性能越强; 3) 在5×10¹⁷ He⁺/cm²注入条件下, 观察到He团簇/泡在纳米结构W(Mo) 和Cu膜中的积聚行为存在明显差异: 在W (Mo) 膜中He团簇/泡的分布与晶粒取向相关, He团簇/泡倾向于沿W (211) 晶面分布; 而Cu膜非晶化且He团簇/泡在其体内呈均匀分布. 关键词： W(Mo)/Cu纳米多层膜 +辐照')" href="#">He⁺辐照 He团簇/泡 相转变     

2.5MeV的He+离子辐照316L不锈钢中氦泡的形核与生长研究

利用透射电子显微镜分析了0.3—0.5T_m温区（T_m为材料溶点）316L奥氏体不锈钢经高剂量氦离子辐照后辐照损伤峰区氦泡的形成行为.实验结果支持氦泡的双原子形核模型，并证实氦泡的形成主要受制于自间隙子/氦置换机制扩散.材料中高密度位错的存在显著增强氦泡形核并抑制氦泡生长.与前人低剂量辐照实验结果的比较表明0.3—0.5T_m温区氦泡形核机制不随辐照剂量或剂量率发生显著变化． 关键词：     

氦离子注入4H-SiC晶体的纳米硬度研究

4H-SiC晶体经能量为100 keV,剂量为3×10¹⁶ cm^-2的氦离子高温（500 K）注入后,再在773—1273 K温度范围内进行了退火处理,最后使用纳米压痕仪测量了样品注入面的硬度.测试结果表明,在500—1273 K温度范围内样品的硬度随退火温度升高呈现先增大后减小再增大的趋势,其中773 K退火样品的硬度增大明显.分析认为,退火样品的硬度变化是由退火过程中缺陷复合与氦泡生长导致样品内部的Si—C键密度、键长和键角改变引起的. 关键词： SiC 注入 氦泡 纳米压痕     

多壁碳纳米管束储氢机理的X射线吸收谱研究

采用X射线吸收精细结构光谱探索性地研究了多壁碳纳米管束.在多壁碳纳米管束不同入射角的X射线吸收精细结构光谱中，观察到C—H σ^*共振峰强度随入射角的变化而发生变化.在常温常压下出现C—H键可能与多壁碳纳米管束中存在缺陷有关，缺陷数量越大C—H σ^*共振峰的强度越大.光谱中C—C π^*和C—C σ^*共振峰强度的变化趋势都不同于C—H σ^*共振峰，这有力地证明了在常温常压条件下氢原子是吸附在多壁碳纳米 关键词： X射线吸收精细结构光谱 碳纳米管 储氢 化学吸附     

快重离子辐照聚酰亚胺潜径迹的电子能损效应

快重离子辐照聚合物材料时，由于密集电离激发在其路径上产生几纳米直径的潜径迹，径迹形貌受离子种类、离子能量等多种因素的影响.为了研究电子能损对径迹形成所起的作用，利用1.158GeV 的Fe⁵⁶离子和 1.755GeV Xe¹³⁶离子在室温真空环境下辐照叠层聚酰亚胺(PI)薄膜，结合傅里叶转换红外光谱(FTIR)分析技术对辐照引起的化学变化进行了测量.聚酰亚胺官能团的降解及炔基的生成是离子辐照聚合物的主要特征，在注量1×10¹¹到6×10¹²/cm²范围及较宽的电子能损(dE/dX)_e范围 (Fe⁵⁶ 离子：2.2 到 5.2 keV/nm， Xe¹³⁶ 离子：8.6 到 11.3 keV/nm)对官能团的断键率及炔基生成率进行了研究. 红外结果显示在实验涉及的能损范围都有炔基生成，应用径迹饱和模型对实验结果进行拟合，不同能损下的平均损伤径迹半径及炔基生成径迹半径被得到，通过热峰模型对实验结果拟合，给出了离子在聚酰亚胺中产生潜径迹的能损阈值，实验给出的径迹形貌的电子能损效应曲线与热峰模型预言走势基本一致. 关键词： 离子辐照 潜径迹 红外光谱 热峰模型     

Co掺杂ZnO纳米棒的共振拉曼光谱和发光特性

采用X射线衍射(XRD)和透射电子显微镜(TEM)手段对微乳液法合成的Zn0.9Co0.1O纳米棒进行了表征.通过室温下的共振拉曼光谱和光致发光光谱手段,研究了所合成纳米材料的共振拉曼光谱和发光特性,并与体相ZnO的研究结果对比,发现合成的材料具有四阶声子紫外共振拉曼散射,而体相材料只有两阶,并观察到在紫外和可见区域所...     

56Fe13+离子引起GaP晶体的微结构损伤

利用X射线衍射（XRD）技术、傅里叶变换红外光谱（FTIR）和Raman光谱对经不同剂量的56Fe13+离子辐照的GaP晶体的微结构进行了表征。结果表明:随着辐照离子剂量的增加,GaP晶体中产生了局部的无序与缺陷。随着56Fe13+离子剂量的增加,Raman光谱展示出振动峰强度逐渐减弱而且一些逐渐消失,但其峰位几乎没有发生变化;XRD显示出GaP晶体的衍射峰的强度逐渐减小;FTIR主要表现为宽化及其强度增加。这表明重离子56Fe13+的辐照使得GaP晶体中的缺陷与无序性增加,导致晶体产生了局部的非晶化。The Misconstructural damage of GaP irradiated with 56Fe13+ to fluences ranging from 1×107 ions/cm2~1×1010 ions/cm2 were analyzed by X-ray diffraction (XRD) techniques, Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The result shows that, with the increase of irradiation ion fluences, local disorder and defects were produced in GaP crystal. With the increase of ion fluence, Raman spectra reveal the intensity of scattering peaks gradually weakens and some scattering peaks gradually disappear, however no changes in the peak position were found. XRD measurement displays that the intensity of diffraction peaks gradually decreases with an increase in ions fluences. Result from FTIR spectra exhibits that the intensity of reflection peaks gradually increases and the FWHM of reflection peaks broadens. These phenomena indicate that, the irradiation of heavy-ion Fe produces defects and disorder in GaP crystal, leading to a local amorphization.     

快重离子辐照对非晶态SiO2薄膜光致发光谱的影响

用湿氧化法在单晶硅表面生长了非晶态SiO2薄膜,再用高能Pb和Xe离子对薄膜进行辐照,最后用荧光光谱分析了辐照参数(剂量、电子能损值)与发光特性改变的相关性.研究发现,快重离子辐照能显著影响薄膜的发光特性,进一步分析显示,辐照导致了SiO2薄膜内O-Si-O缺陷、缺氧缺陷和非桥式氧空位缺陷的产生,且缺氧缺陷和非桥式氧空...     

快重离子辐照对MoS2热导率的影响研究

利用0.97 GeV的209Bi离子辐照二硫化钼（MoS₂）晶体,辐照注量范围为1×1010～1×1012 ions/cm2,结合原子力显微镜（AFM）观测和Raman光谱分析研究了快重离子辐照对MoS₂热导率的影响。实验结果显示,快重离子辐照在MoS₂中产生了潜径迹,较高激光功率下的Raman测试使样品局部温度升高,导致E_1/2g和A_1g峰随注量增加向低波数方向移动,且峰形展宽。引入了通过改变激光功率测量Raman光谱得到MoS₂热导率的计算方法,获得了不同辐照注量下MoS₂的热导率的定量分析结果,随注量增加,热导率不断降低,从未辐照样品的563 W/mK下降到1×1012 ions/cm2辐照时的132 W/mK。Molybdenum disulphide (MoS₂) was irradiated by 0.97 GeV 209Bi ions with the fluence of 1×1010 to 1×1012 ions/cm2. The irradiation effect on the thermal conductivity of MoS₂ was analyzed by atomic force microscope (AFM) and Raman spectroscopy. The experimental results show that hillock-like latent tracks are observed on irradiated MoS₂ by AFM. The measurement of MoS₂ by Raman spectrometer with high laser power results in the increase of local temperature of MoS₂, which cause the downshift of peaks position and broadening of E_1/2g and A_1g peak. Furthermore, according to Raman spectra measured at different laser power, thermal conductivity of MoS₂ before and after irradiation was calculated, which show that the thermal conductivity of MoS₂ decreases with increasing fluence, from 563 to 132 W/mK for pristine and 1×1012 ions/cm2 irradiated MoS₂, respectively.     

Proton radiation effect on GaAs/AlGaAs core–shell ensemble nanowires photo-detector

We demonstrate that the GaAs/AlGaAs nanowires(NWs) ensemble is fabricated into photo-detectors. Current–voltage(I–V) characteristics are measured on Ga As/Al Ga As core–shell ensemble NW photo-detectors at room-temperature before and after 1-MeV proton irradiation with fluences from 1.0 × 10~(13) cm~(-2) to 5.0 × 10~(14) cm~(-2). The degradation of photocurrent suggests that the point defects induced by proton radiation could cause both carrier lifetime and carrier mobility to decrease synchronously. Comparing with a GaAs quantum well, the degradations of light and dark current for the irradiated NWs photo-detector indicate that NWs material is a preferable potential candidate for space applications.     

Evolution of helium bubbles in nickel-based alloy by post-implantation annealing

Nickel-based alloys have been considered as candidate structural materials used in generation IV nuclear reactors serving at high temperatures. In the present study, alloy 617 was irradiated with 180-keV helium ions to a fluence of 3.6×10¹⁷ ions/cm² at room temperature. Throughout the cross-section transmission electron microscopy (TEM) image, numerous over-pressurized helium bubbles in spherical shape are observed with the actual concentration profile a little deeper than the SRIM predicted result. Post-implantation annealing was conducted at 700 ℃ for 2 h to investigate the bubble evolution. The long-range migration of helium bubbles occurred during the annealing process, which makes the bubbles of the peak region transform into a faceted shape as well. Then the coarsening mechanism of helium bubbles at different depths is discussed and related to the migration and coalescence (MC) mechanism. With the diffusion of nickel atoms slowed down by the alloy elements, the migration and coalescence of bubbles are suppressed in alloy 617, leading to a better helium irradiation resistance.     

Study on irradiation-induced defects in GaAs/AlGaAs core–shell nanowires via photoluminescence technique

To gain a physical insight into the radiation effect on nanowires(NWs), the time resolved photoluminescence(TRPL)technique is used to investigate the carrier dynamic behaviors in GaAs/AlGaAs core–shell NWs before and after 1-MeV proton irradiation with fluences ranging from 1.0 × 10~(12) cm~(-2) to 3.0 × 10~(13) cm~(-2). It is found that the degradations of spectral peak intensity and minority carrier lifetime show similar trends against irradiation fluence, which is closely related to the displacement defects induced by irradiation. We also find that the proton irradiation-induced defects behave as Shockley–Read–Hall(SRH) recombination center trapping free carriers. Finally, the defect concentration could be estimated through measuring the minority carrier lifetime.     

退火对Pb辐照Al2O3单晶发光特性的影响

研究了230MeV的²⁰⁸Pb²⁷⁺辐照Al₂O₃样品及随后在600,900,1100K高温条件下退火后的光致发光特性。从辐照样品的测试结果可以清楚地看到在波长为390,450nm处出现了强的发光峰。辐照量为1×10¹³ions/cm²时,样品的发光峰最强。经过600K退火2h后测试结果显示,380nm发光峰剧烈增强,而其他发光峰显示不明显。在900K退火条件下,380nm的发光峰开始减弱,而在360,510nm出现了明显的发光峰,至到1100K退火完毕后380nm的发光峰完全消失,而360,510nm的发光峰相对增强。从被辐照样品的FTIR谱中看到,波数在460~510cm^-1间的吸收是振动模式,经过离子辐照后,吸收带展宽,随着辐照量的增大,Al₂O₃振动吸收峰消失,说明Al₂O₃振动模式被完全破坏。1000~1300cm^-1之间为Al—O—Al桥氧的伸缩振动模式,辐照后吸收带向高波数方向移动,说明其振动模式受到影响。辐照剂量较小的样品,损伤程度相对较低,经退火晶化后,振动模式基本恢复到单晶状态;辐照剂量较高的样品,损伤程度大,退火处理后表面变得较粗糙,振动模式并未出现,说明结构破坏严重。     

In-situ TEM observation of the evolution of helium bubbles in Mo during He+ irradiation and post-irradiation annealing

The evolution of helium bubbles in purity Mo was investigated by in-situ transmission electron microscopy (TEM) during 30 keV He⁺ irradiation (at 673 K and 1173 K) and post-irradiation annealing (after 30 keV He⁺ irradiation with the fluence of 5.74×10¹⁶ He⁺/cm² at 673 K). Both He⁺ irradiation and subsequently annealing induced the initiation, aggregation, and growth of helium bubbles. Temperature had a significant effect on the initiation and evolution of helium bubbles. The higher the irradiation temperature was, the larger the bubble size at the same irradiation fluence would be. At 1173 K irradiation, helium bubbles nucleated and grew preferentially at grain boundaries and showed super large size, which would induce the formation of microcracks. At the same time, the geometry of helium bubbles changed from sphericity to polyhedron. The polyhedral bubbles preferred to grow in the shape bounded by {100} planes. After statistical analysis of the characteristic parameters of helium bubbles, the functions between the average size, number density of helium bubbles, swelling rate and irradiation damage were obtained. Meanwhile, an empirical formula for calculating the size of helium bubbles during the annealing was also provided.     

CVD法单层MoS2在209Bi离子辐照下的损伤效应研究

通过光学显微镜、拉曼光谱确定了CVD（化学气相沉积法）制备的不同厚度MoS₂的层数,采用拉曼分析结合原子力显微镜观测分析了由HIRFL提供的高能209Bi离子辐照CVD制备的单层MoS₂样品随辐照注量的损伤规律。随辐照注量增加,E_2g1和A_1g两种声子振动模式对应的拉曼峰逐渐蓝移,且拉曼特征峰强度减弱,这是由于带正电荷的209Bi辐照产生潜径迹型晶格缺陷吸附空气中氧分子而引入p型掺杂引起的。同时,在辐照注量为5×1010 ions/cm2的单层MoS₂的AFM图像中观察到潜径迹主要以凹坑形式出现,与机械剥离法观测到的凸起径迹明显不同,分析了不同制备工艺对径迹形貌的影响。比较了机械剥离法制备MoS₂样品的拉曼光谱和AFM成像的实验数据和结果,认为不同制备方法会影响单层或少层MoS₂的电子密度。The layer number of MoS₂ with different thickness was determined by the optical microscope and Raman spectra. And the damage effect of the CVD (chemical vapor deposition) prepared single-layer MoS₂ sample irradiated by 209Bi ions was analyzed by the combination of Raman analysis and AFM observations. With the increase of irradiation fluence, the Raman characteristic peaks of E_2g1 and A_1g corresponding to both phonon vibration modes gradually bluely shift, and the intensity of the peaks obviously decreased. This is due to the fact that the 209Bi ion irradiation results in the latent track type lattice defects and they adsorb the oxygen molecules in the air ended with the p-type doping. Meanwhile, from the AFM image of the mono-layer of irradiated MoS₂ under the 5×1010 ions/cm2, it can been seen that latent tracks mainly occur in the form of pits, which different from the hillock tracks observed by mechanical stripping method. The influence of different preparation technology to the track morphology is analyzed. Compared with the Raman and AFM results of MoS₂ prepared by mechanical stripping, it is considered that different preparation methods will affect the electron density in single or few layers of MoS₂.     

Raman and near-IR study on proton irradiated CR-39 detector and the effect of air-leak on damage formation

Raman and near-IR spectral studies have been made on the proton irradiated CR-39 plastics with 3.4 MeV at fluences ranging from 10¹⁰ to 10¹⁴ ionscm⁻². The density of –CH₂– group began to decrease after the air leak subsequent to the irradiation. This implies an important role of the oxygen on forming the permanent damage along the latent track. Production of OH group and some types of radicals was confirmed by near-IR observations in the air.