硅烷对纳米硅薄膜微结构和光学性能的影响

通过改变反应气体中硅烷体积分数,采用直流偏压辅助等离子体化学气相沉积法在玻璃衬底上沉积本征氢化纳米硅薄膜.使用拉曼光谱仪、原子力学显微镜和紫外可见光透射仪对薄膜进行测试,研究不同硅烷体积分数对薄膜微结构和光学性能的影响.结果表明:当硅烷体积分数增加,晶粒尺寸增加,而晶态含量却随之下降.晶态含量的降低,使拉曼光谱中谱峰的强度降低,峰位发生蓝移,薄膜有序性随之降低;而且薄膜的光学禁带宽度随硅烷体积分数的增加而增加.当硅烷体积分数为1.3%时,沉积本征氢化纳米硅薄膜,薄膜中晶粒分布均匀,其生长存在取向性.此时晶态含量约为50%,晶粒尺寸约为2.6 nm;薄膜具有较大的光学禁带宽度,为1.702 eV,以及较高的电导率.     

Spin dynamics characteristics of nitrogen vacancy spins in diamond films using enhanced Raman shift with spin microscopy

The diamond films were deposited on a Si substrate with chemical vapor deposition MCVD using methanehydrogen gas.Raman active phonon and sp~2/sp~3 ratio in diamond/Si(100)films were investigated by Raman spectra in the difference scattering configurations.Furthermore,the Raman scattering spectrum of diamond/Si(100)hetero-junction was measured with different thickness to investigate the spin dynamics of nitrogen vacancy spins.The Fluorescence scanning microscopy indicated that nitrogen vacancy center electron spin was coupled to the host nitrogen nuclear spin by the electron spin resonance.The strong peak of 1332 cm~(-1)displayed the F_(2g)symmetry of diamond,while the broad E_(2g)mode peak of 1550 cm~(-1)was a broad band G mode,and 1150 cm~(-1)peak corresponded to the nano-diamond and disordered graphitic carbon form with disordered SP~2 hybridization.The Raman spectra of the diamond films were observed as a function of the residual stress,crystal size and their orientation.The peaks of 1132 cm~(-1)and 1480 cm~(-1)were associated with hydrogen bonding.The transport of diamond exhibited sp~3 spin related effect.The diamond/Si(100)PDOS is the results of spin-related couple of sp~3,p and d orbital hybridization.The spin dynamics was achieved by the orbital competition,strong crystal field and charge order.     

直流电弧等离体喷射CVD金刚石生长面的浸润性研究

为了开展CVD金刚石生长面的浸润性研究,采用直流电弧等离体喷射技术,制备了纳米金刚石自支撑膜、微米金刚石自支撑膜以及毫米单晶金刚石.结果发现：对于相同的金刚石生长表面,接触角按甘油、饱和葡萄糖水溶液、饱和NaCl水溶液和蒸馏水的顺序逐渐增大,表明所制备金刚石的表面对各液体的浸润性逐渐变差;而对于同种滴液,接触角在不同的金刚石表面表现出不同的大小,说明不同的CVD金刚石对于同种液体具有不同的浸润性.而表面能的计算结果表明纳米金刚石自支撑膜生长面的表面能最高,其次是微米自支撑金刚石膜,而单晶金刚石的表面能最小.     

利用巴克豪森效应测量铁磁材料的晶粒度

本文研究了铁磁材料的晶粒度与巴克豪森噪声 (BN )强度、波形特征参数之间的关系 ,提出用波形半高宽的占空比 μ作为测量参数 ,能较好地表征晶粒度的大小。     

表面和界面效应对纳米晶粒尺寸的影响

应用热力学方法，讨论了非晶晶化法制取纳米晶体时所得最小晶粒与晶化温度的关系．发现当退火温度为物体熔点的1／2时，可制得最小晶粒，而在此温度下，过冷液体与晶体之间的Gibbs自由能之差达到最大值．考虑到样品较薄时较为明显的表面效应，计算了金属样品厚度对晶粒最小尺寸的影响．结果表明，晶粒的最小限度不仅受晶化过程中自由能差的影响，还与晶体厚度有关．样品厚度越小，对生成的最小晶粒尺寸影响越大．     

Synthesis of boron-doped diamond with laser heated diamond anvil cell

Boron-doped diamond has been synthesized from graphite mixed with different ratio of B₄C at high pressure high temperature (HPHT) using laser heated diamond anvil cell. The starting composition was transformed to diamond compound at pressure ∼9 GPa, 2300–2400 K as indicated by the in-situ X-ray diffraction pattern with synchrotron radiation source. Raman spectrum of the recovered specimen from HPHT state confirmed that boron has been doped into diamond lattice.     

金刚石产品的脉冲激光制备与应用

详细介绍了用脉冲激光法制备金刚石产品的发展过程 ,并总结了脉冲激光沉积 (PLD)、液体靶脉冲激沉积 (LYPLD)以及脉冲激光诱导液 -固界面反应 (PLIIR)等几种典型的实验方法、实验装置以及所取得的成果 在脉冲激光沉积法 (PLD)制备金刚石薄膜方面重点总结了最近比较新颖的液体靶脉冲激光沉积技术 ,而在金刚石纳米晶的制备方面综述了脉冲激光诱导液 -固界面反应法 ,此法在制备亚稳态纳米晶体方面显示出了较独特的优越性 图 4,参 1 6     

利用金刚石纳米粉引晶方法制备高硼掺杂金刚石薄膜

利用金刚石纳米粉引晶方法在SiO2衬底上合成了高硼掺杂金刚石薄膜,并利用范德堡法、扫描电镜、激光拉曼方法对不同掺杂量下生长的样品进行了表征.SEM和拉曼谱分析表明,少量掺杂时有利于提高金刚石薄膜的质量,但是随着掺杂量的增加,金刚石薄膜质量开始明显下降;并且拉曼谱峰在500 cm-1和1200 cm-1开始加强,呈现重掺杂金刚石薄膜的典型特征.其电导率随着温度升高而升高,表明导电性质为半导体导电.     

金刚石薄膜的制备、表征和场发射性能

系统研究了在微波等离子体化学气相沉积(MPCVD)系统中,甲烷浓度、沉积气压、气体流量比、衬底的预处理等参数工艺对金刚石薄膜质量的影响,不同样品的扫描电镜(SEM)图片表明上述参数工艺对金刚石薄膜的微观形貌如:晶粒尺寸、均匀性、膜的连续性、致密性等具有重要影响.金刚石薄膜样品尖锐的1332cm-1Raman峰表明金刚石膜具有很高的晶化质量,与SEM图片一致.最后研究了样品的场发射特性,获得了较低的发射阈值电压4.4V/μm,电压为650V时,得到较高的约128mA/cm2的发射电流密度.     

Orientation variation along growth direction of millimeter free-standing CVD diamond thinned by mechanical grinding

A free-standing diamond film with millimeter thickness prepared by DC arc plasma jet was thinned successively by mechanical grinding. The orientation and quality of the diamond films with different thicknesses were characterized by X-ray diffraction and Raman spectroscopy, respectively. The results show a random grain-orientation distribution during the initial growth stage. As the film thickness increases, the preferred orientation of the diamond film changes from (111) to (220), due to the competitive growth mechanism. Twinning generated during the nucleation stage appears to stabilize the preferential growth along the 〈110〉 direction. The interplanar spacing of the (220) plane is enlarged as the film thickness increases, which is caused by the increase of non-diamond-phase carbon and impurities under the cyclic gas. In addition, the quality of the diamond film is barely degraded during the growth process. Furthermore, the peak shift demonstrates a significant inhomogeneity of stress along the film growth direction, which results from competitive growth.     

微波ECR等离子体化学汽相沉积金刚石膜的研究

本文利用微波电子回旋共振（ＥＣＲ）等离子体化学气相沉积（ＣＶＤ）法在较低气压下进行了金刚膜的沉积工艺研究，发现ＣＨ４气体的浓度可适当提高至ＣＨ４／Ｈ２＝０．８。所得的Ｒａｍａｎ谱图证实在该条件下得到的膜比在ＣＨ４／Ｈ２较小情况下得到的膜含有更多的金刚石相。     

表面光滑的金刚石薄膜的合成

以[CH4+H2]为反应气体,利用EACVD的方法在Si(100)衬底合成了表面光滑的超薄金刚石薄膜.利用扫描电子显微镜(SEM)、显微喇曼光谱、X射线衍射等手段对合成的金刚石薄膜的成分与结构进行了分析.实验得到了生长表面光滑、厚度均匀的超薄金刚石薄膜的最佳条件.     

Growth and characterization of large, high quality cubic diamond crystals

High quality cubic diamond crystals were grown using the temperature gradient method at high pressure and high temperature(HPHT),in a new FeNi alloy as solvent.The crystals were grown at relatively low temperatures suitable for the growth of {100} faces.An increase in the radial growth rate,and inhibition of the axial growth caused the growth of large,high quality cubic diamond single crystals at high growth rates.For example,over 33 h,the radial growth rate was 0.22 mm/h,while the axial growth rate was only 0.08 mm/h;the growth rate by weight was also increased to 7.3 mg/h.The yellow color of our crystal samples was more uniform than samples from Sumitomo Corporation of Japan and Element Six Corp.The Raman FWHW of the 1332 cm 1 peak in our diamond sample was smaller than the Element Six Corp.sample,but larger than that of the Sumitomo Corp.sample.The nitrogen content of our diamond samples was 240 ppm,which was much higher than the Sumitomo and Element Six samples because of the higher growth rate of our diamond samples.     

355 nm YAG皮秒脉冲激光晶化非晶硅薄膜的研究

 使用355 nm YAG皮秒脉冲激光对250 nm厚的非晶硅薄膜进行激光晶化的研究,并利用金相显微镜、拉曼光谱和X射线能谱（EDS: energy dispersive spectrometer）等对晶化样品进行了分析。结果表明：随着激光脉冲能量的增加,完全熔区和部分熔区的宽度均明显增大。在所研究的脉冲能量范围内（15 μJ—860 μJ）,所有样品的完全熔区的拉曼光谱均无非晶硅或晶体硅的特征峰,而位于完全熔区边缘的部分熔区的拉曼光谱却显示出晶体硅的特征峰,这可能是因为完全熔区接受到的激光能流密度过大,造成区内绝大部分非晶硅薄膜气化蒸发。这个推测进一步得到了X射线能谱分析结果的证实。X射线能谱分析结果表明,完全熔区的成份主要是玻璃与硅反应生成的硅化物,其表面被二氧化硅层所覆盖。     

ZnO纳米晶的拉曼光谱

通过溶胶-凝胶法制备了5~31 nm氧化锌纳米晶,测量了它们的拉曼光谱,结果表明二级拉曼模随粒径减小相对强度增大,归因于尺寸效应.新出现的938 cm-1模指认为来自表面氧空位.     

氮气流量对金刚石膜生长的影响

采用电子辅助热灯丝化学气相沉积（EA-CVD）方法沉积大面积金刚石膜,在金刚石膜的沉积过程中,氮气流量对金刚石膜沉积的影响会直接影响着金刚石膜的生长和质量。用Raman等手段对金刚石膜的生长特性进行了表征。     

甲醇和乙醇的激光喇曼光谱

采用激光喇曼方法,对甲醇和乙醇液体样品进行了喇曼光谱研究,得到了上述样品的喇曼光谱,并对其进行了归属.经过分析比较,给出了检测甲醇的特征谱线,为假酒鉴别、深入研究甲醇和乙醇的能级结构等提供了可供借鉴的参考.     

甲烷浓度对光学级金刚石膜生长的影响

采用微波PCVD系统进行了高品质透明金刚石膜的制备,在金刚石膜的沉积过程中,碳源浓度的变化直接影响着金刚石膜的生长和质量。用Raman,SEM等手段对金刚石膜的生长特性进行了表征。     

多层金刚石薄膜制备工艺和应力分析研究

采用热丝化学气相沉积方法,优化金刚石薄膜制备工艺。通过改变甲烷浓度成功制备出厚度均匀的多层金刚石薄膜,实现了多种调制周期的金刚石薄膜制备,调制周期最小至100 nm。通过拉曼光谱和X射线衍射方法对单层以及多层金刚石薄膜进行应力分析,发现单层结构中,微米金刚石薄膜应力最大,随着金刚石晶粒尺寸的减小,薄膜应力减小;多层金刚石薄膜结构中,微米层与纳米层均匀交替生长,有效地降低了薄膜应力,有利于提高金刚石薄膜在应用中的稳定性。     

甲烷浓度对大面积金刚石膜生长的影响

采用电子辅助热灯丝化学气相沉积(EA.CVD)方法沉积大面积金刚石膜,在金刚石膜的沉积过程中,碳源浓度的变化会直接影响着金刚石膜的生长和质量。使用Raman,SEM等手段对金刚石膜的生长特性进行了表征。