超纳米金刚石薄膜场发射特性的研究

超纳米金刚石(UNCD)是一种全新的纳米材料，具有许多独特性能。介绍了Si微尖和微尖阵列阴极沉积超纳米金刚石薄膜的工艺及其场发射特性。研究发现，适当的成核工艺和微波等离子体化学气相沉积工艺可在Si微尖上沉积一层光滑敷形的金刚石薄膜；沉积后阴极的电压-电流特性、发射电流的稳定性以及工作在氧气环境下的发射特性都获得明显提高。讨论了超纳米晶金刚石薄膜阴极的发射机理。     

微波等离子体沉积金刚石薄膜

结合自己的研究工作,介绍了微波等离子体沉积金刚石薄膜的优点及其应用;还介绍了美、英、苏等国利用微波等离子体沉积金刚石薄膜的最新动向。     

H2-O2混合气氛刻蚀制备金刚石纳米晶薄膜

提供了在镜面抛光Si衬底上沉积平滑的纳米金刚石（NCD）薄膜的方法。采用微波等离子体化学气相沉积（CVD）系统，利用H2、CH4和O2为前驱气体，在镜面抛光的Si基片上制备了直径为5cm的NCD薄膜，用扫描电镜（SME）和共焦显微拉曼光谱分析其表面形貌和结构特点。分析表明，利用这种方法可以制备出高sp^3含量的NCD薄膜。通过与沉积时间加长而沉积条件相同情况下合成的金刚石微晶薄膜形貌相对比，分析了H2-O2混合气氛刻蚀制备NCD薄膜的机理。分析表明，基底的平滑度对O2的刻蚀作用起到重要的影响；在平滑的基底上，含量较少的O2的刻蚀作用也很明显；随着基底的平滑度下降，混合气氛中O2的刻蚀作用逐渐减弱。     

利用正交实验制备金刚石薄膜及其场发射的研究

场发射阴极金刚石薄膜的制备方法有很多,本文是利用微波等离子化学气相沉积的方法制备薄膜,文中详细介绍了正交分解法实验制备金刚石薄膜的过程。并对薄膜进行扫描电镜、拉曼光谱、X射线实验,分析了其形貌与结构;用场发射二级结构研究薄膜的场发射性能,简单分析了金刚石薄膜的成因和场发射的性能。     

RF—HFCVD生长高质量纳米金刚石薄膜

采用射频等离子体增强的热丝化学气相沉积 (RF HFCVD)技术在石英玻璃衬底上制备了高质量的纳米金刚石薄膜 .研究了衬底温度、反应气压及射频功率对金刚石膜的结晶习性和光学性质的影响 ,其最佳值分别为70 0℃、2× 133Pa和 2 0 0W .在该条件下金刚石成核密度达 10 11cm-2 ,经 1h生长即获得连续薄膜 ,其平均晶粒尺寸为 2 5nm ,表面粗糙度仅为 5 5 ,在近红外区域 (80 0nm处 )的光透过率达 90 % .     

微米金刚石聚晶薄膜场发射点的研究

采用微波等离子化学气相沉积方法,以甲烷和氢气为反应气体,在镀有金属钛的陶瓷衬底上,制备了微米金刚石聚晶薄膜.利用扫描电镜、拉曼光谱、X射线光电子能谱对薄膜的化学组成、微观结构和表面形貌进行了表征.用二级结构的场发射仪和扫描隧道显微镜研究了薄膜的场发射性能,结果表明微米金刚石聚晶薄膜发射点主要来源于聚晶颗粒.进一步研究了单个聚晶颗粒表面不同区域的发射性能,发现多种因素对场发射的性能有影响.     

微米金刚石薄膜的制备与场发射研究

利用微波等离子体化学气相沉积（MPCVD）法,在镀金属钛层的陶瓷基底上面,调整优化沉积参数,制备出了碳膜。通过各种仪器分析了碳膜的内部结构和表面形貌,证明该碳膜是微米金刚石薄膜。进一步将微米金刚石薄膜作为场发射阴极材料,测试了其场致电子发射特性。稳定发射状态下的开启电场为1.15V/μm, 在3.35V/μm的电场下,其场发射电流密度为0.81mA/cm2,发射点密度约为104/ cm2。并对其发射机理进行了研究。     

碳纳米球薄膜的场发射特性

利用微波等离子体化学气相沉积法,在Si(100)衬底上制备了碳纳米球薄膜。利用拉曼光谱和场发射扫描电子显微镜研究了薄膜的结构以及表面形貌,表明碳纳米球薄膜是由约2～3μm长、100nm宽的无定形碳纳米片相互缠绕、交织成球状而构成的。在高真空系统中测量了碳纳米球薄膜的场发射特性,结果表明,碳纳米球薄膜具有良好的场发射特性,阈值电场为3.1V/μm,当电场增加到10V/μm时,薄膜的场发射电流密度可达到60.7mA/cm2。通过三区域电场模型合理地解释了碳纳米球薄膜在低电场、中间电场和高电场区域的场发射特性。     

提高微米金刚石聚晶薄膜的场发射点密度研究

利用微波等离子化学气相沉积的方法,制备出微米金刚石聚晶颗粒薄膜,通过扫描电镜、拉曼光谱、X射线实验,分析了薄膜的形貌与结构,用场发射二级结构研究薄膜的场发射性能.研究了微米金刚石聚晶薄膜的产生的机理,调整制备过程中的参数来增加聚晶颗粒的密度,提高场发射点的密度,为制备大面积、均匀的场发射阴极打下基础.     

纳米金刚石在不同沉积条件下的生长研究

用CH4和H2为反应气体，在热丝化学气相沉积系统中用不同的沉积条件直接在Si衬底上制备了纳米金刚石，并用高分辨扫描电子显微镜和显微Raman光谱仪对它们进行了表征。结果表明，在热丝化学气相沉积系统中用连续辉光放电在Si衬底上沉积的金刚石是纳米金刚石颗粒；而用辉光放电在Si衬底上先进行金刚石核化，然后再用热丝化学气相沉积生长，可形成纳米金刚石膜。不同结构纳米金刚石的形成主要是由于在不同的沉积条件下非金刚石相被刻蚀的程度不同以及形成金刚石前驱物的运动不同所致。     

MPCVD中基片加热材料的温度场摄动模型研究

为改进微波等离子体化学气相沉积（MPCVD）装置中的加热系统，提出了用基片加热材料替代常规加热方式的新的技术路线，建立了基片加热材料的微波轴对称温度场模型并得到了一般解，通过对基片加热材料的微波设计，在MPCVD装置中获得大片基片台直径的均匀温度分布区。     

Two-step fabrication of thin film encapsulation using laser assisted chemical vapor deposition and laser assisted plasma enhanced chemical vapor deposition for long-lifetime organic light emitting diodes

A thin film encapsulation layer was fabricated through two-sequential chemical vapor deposition processes for organic light emitting diodes (OLEDs). The fabrication process consists of laser assisted chemical vapor deposition (LACVD) for the first silicon nitride layer and laser assisted plasma enhanced chemical vapor deposition (LAPECVD) for the second silicon nitride layer. While SiN_x thin films fabricated by LAPECVD exhibits remarkable encapsulation characteristics, OLEDs underneath the encapsulation layer risk being damaged during the plasma generation process. In order to prevent damage from the plasma, LACVD was completed prior to the LAPECVD as a buffer layer so that the laser during LACVD did not damage the devices because there was no direct irradiation to the surface. This two-step thin film encapsulation was performed sequentially in one chamber, which reduced the process steps and increased fabrication time. The encapsulation was demonstrated on green phosphorescent OLEDs with I–V-L measurements and a lifetime test. The two-step encapsulation process alleviated the damage on the devices by 19.5% in external quantum efficiency compared to the single layer fabricated by plasma enhanced chemical vapor deposition. The lifetime was increased 3.59 times compared to the device without encapsulation. The composition of the SiNx thin films was analyzed through Fourier-transform infrared spectroscopy (FTIR). While the atomic bond in the layer fabricated by LACVD was too weak to be used in encapsulation, the layer fabricated by the two-step encapsulation did not reveal a Si–O bonding peak but did show a Si–N peak with strong atomic bonding.     

Remote plasma-enhanced CVD of silicon: Reaction kinetics as a function of growth parameters

The reaction kinetics in Remote Plasma-enhanced Chemical Vapor Deposition (RPCVD) have been studied for a chamber pressure of 200 mTorr, rf powers between 4 and 8 W, diluted silane flow rates between 5 and 40 sccm, and temperatures between 190 and 480° C. The observed temperature dependence of growth rate reveals a change in activation energy at 300–325° C, suggesting that hydrogen desorption is the rate limiting step in the deposition reaction. A strong dependence of growth rate on rf power has been attributed in part to the extension of the glow discharge region closer to the substrate at higher rf powers. Growth rate has been shown to increase when the sample is positioned closer to the glow, indicating that the reaction precursor is a short-lived species, probably SiH₂ or SiH₃. Growth rate has been shown to exhibit a sublinear dependence on silane partial pressure. Oxygen incorporation in the deposited films has been studied using Secondary Ion Mass Spectroscopy (SIMS), and it has been found that the main source of oxygen contamination is the process gases. However, it has also been found that “point of use” purification of the process gases reduces water and oxygen contamination significantly, reducing the oxygen incorporation in the films by an order of magnitude.     

高功率光纤激光器用20/400双包层掺镱光纤

采用改进化学气相沉积结合溶液掺杂法制造出了掺镱石英光纤预制棒,预制棒轴向上芯径波动小于5%,折射率差波动小于8%。研磨加工后拉制出20/400双包层掺镱光纤,光纤纤芯不圆度为2%,芯包同心度偏差为0.87 μm。双包层掺镱光纤在1095 nm的包层损耗为2.1 dB/km。采用拉制的掺镱双包层光纤作为直接振荡结构全光纤化激光器的增益光纤实现了1195 W的1080 nm激光输出,斜率效率达82%。     

The compositional grading of MOCVD-grown GaAs1−xPx via substrate temperature changes

The first application of MOCVD compositional grading by means of substrate temperature changes is reported for the case of GaAs−P_x (0 ≤ x ≤ 0.30). The method is based upon the higher pyrolysis efficiency ratio of AsH₃ relative to PH₃ at lower growth temperatures. The growth upon GaAs substrates commences at a temperature at which this PH₃/ASH₃ thermal cracking efficiency ratio is extremely high; raising the growth temperature decreases this ratio, and hence the As/P ratio in the solid. GaAs_1−xP_x epilayers grown on GaAs by this method display excellent materials properties and are virtually optically and electrically indistinguishable from conventionally-graded epilayers in which the gas phase mole fractions of transport agents are varied at constant temperature. The method is applicable to systems where temperature-dependent cracking efficiency differentials exist.     

金刚石薄膜的形成及其场发射特性研究

研究了金刚石聚晶碳膜的生长过程,以及不同生长阶段碳膜的场发射性能。通过磁控溅射法在陶瓷上镀一层金属钛作为制备碳膜的衬底,将衬底放入微波等离子体化学气相沉积腔中,经过不同的沉积时间制备出一系列的碳膜。利用SEM、Raman光谱仪、X射线衍射仪等仪器,对碳膜进行了形貌与成分分析,最后利用二极结构场发射装置,测试了碳膜的场发射性能。着重讨论了金刚石聚晶碳膜生长过程中的变化,并且对金刚石聚晶碳膜的场发射机理进行了深入研究。     

基于不同金属衬底制备碳膜的场发射研究

利用磁控溅射的方法,在相同的陶瓷衬底上面分别镀上三种不同金属,形成三种不同的金属衬底,对金属层进行相同的表面处理后,放入微波等离子体化学气相沉积腔中,制备出三种碳膜。对制备出不同的碳膜用扫描电镜、拉曼光谱、X射线衍射仪进行结构分析,并用二极管型结构测试了它们的场致发射电子的性能。找到了最适合场发射的金属衬底,进一步对不同金属衬底制备碳膜的场发射特性不同的原因进行了初步的研究。     

C-H体系CVD金刚石薄膜取向生长的热力学分析

化学气相淀积金刚石薄膜过程中 ,CH3 和C2 H2 是金刚石生长的主要前驱基团。C2 H2 与CH3 浓度比 ( [C2 H2 ]/[CH3 ])的变化将影响金刚石薄膜的生长取向。用非平衡热力学耦合模型计算了C H体系CVD金刚石薄膜生长过程中C2 H2 浓度和CH3浓度随淀积条件的变化 ,并进一步获得了 [C2 H2 ]/[CH3 ]随衬底温度和CH4浓度的变化关系 ,从理论上探讨了金刚石薄膜 ( 1 1 1 )面和 ( 1 0 0 )面取向生长与淀积条件的关系。在衬底温度和CH4浓度由低到高的变化过程中 ,[C2 H2 ]/[CH3 ]逐渐升高 ,导致金刚石薄膜的形貌从 ( 1 1 1 )晶面转为 ( 1 0 0 )晶面。