【作者】 王杨；

【导师】 朱嘉琦；

【作者基本信息】 哈尔滨工业大学 ， 材料学， 2015， 硕士

【摘要】 金刚石的异质外延生长过程需要高质量的衬底材料,为了得到异质外延的高度定向金刚石薄膜,需要设计一种能够高度取向一致生长的适合金刚石异质生长的衬底材料,本文通过模拟方法设计了一种合适的衬底结构,并实验中通过工艺参数的调整来进行其制备和表征工作。本文利用模拟和实验的方法,分别对所设计的结构和制备的薄膜进行了相关的研究。模拟部分利用Materials Studio材料学分析计算软件进行,说明了为何采用铱(Ir)有利于金刚石异质外延生长以及Ti N过渡层对于整个结构所起到的作用。实验部分在对单多晶金刚石的特性进行了测试和表征、制备了合适的镀膜靶材并通过预氧化的清洗工艺得到了洁净的Si衬底后,利用脉冲激光沉积(PLD)法在不同的沉积条件下制备了Ti N薄膜、Mg O薄膜和Mg O/Ti N叠层,并利用台阶仪、扫描电子显微镜(SEM)、原子力显微镜(AFM)、X射线光电子能谱(XPS)、掠入射X射线衍射仪(GIXRD)、纳米力学系统(纳米压痕、纳米划痕)等对其形貌、粗糙度、成分和结合能、结构和力学性能进行了表征。根据衬底的设计准则,设计了一种以Si(100)衬底为基础且可以达到异质外延效果的膜系,其结构为Si(100)/Ti N(100)/Mg O(100)/Ir(100)。通过Materials Studio模拟计算,获得了Ti N、Mg O陶瓷的性能,以及Mg O薄膜与Si衬底上氧化层以及Ti N薄膜结合的性能,表明Ti N过渡层模板的存在在Ti N/Mg O叠层之间建立了类似化学键结合的Ti-N-Mg-O键,对于提高薄膜体系的结合性能有重要的作用。并且,在铱(Ir)衬底上异质外延金刚石有着在Si衬底上没有的有利于金刚石形核的碳原子的吸附-溶解-析出过程。在预先性试验部分,首先利用傅里叶红外光谱仪(FTIR)对高温高压法和化学气相沉积法制备的单多晶金刚石进行了光学性能的表征,确定了性能标准。同时对Si片表面进行了改进的清洗方法,得到了可以用于后续脉冲激光沉积实验的Ti N和Mg O靶材。本文制得了具有原子级平滑表面(粗糙度Ra<0.3 nm)并具有高度(100)取向的准单晶Ti N薄膜和Mg O/Ti N叠层,随着激光能量、衬底温度和脉冲频率的增加,薄膜的质量有所提高,表现为更加平滑的表面、粒子间更好的结合性能(键的结合能升高)、取向一致性更加明显且力学性能有一定程度的提高。并且,当直接在Si衬底上制备Mg O薄膜时,薄膜表现出Periclase相和Magnesium Oxide相共存的结构,而合适厚度的Ti N层的引入能够使Mg O薄膜中仅有Periclase一相,Ti N过渡层模板的引入对提高Mg O薄膜的取向一致性和沉积质量有显著的作用。本文制备了表面平滑且具有高度一致取向的薄膜叠层结构,为高质量金刚石薄膜的生长提供了可能性。并发现对于在利用脉冲激光沉积法(PLD)制备薄膜的过程中,采用较高的激光能量、衬底温度和激光脉冲频率,可以显著提高薄膜的质量,对于在合适的条件下制备的薄膜,发现激光能量和衬底温度具有一定的补偿性能,激光能量的提高为粒子带来额外的能量在衬底表面迁移,可以补充衬底温度的不足所引发的粒子堆积。同时,对薄膜与衬底及过渡层结合的界面的结构进行了分析,其界面特征衍射峰随薄膜的成分和沉积状态的变化而变化,可以在一定程度上说明薄膜的外延特性。更多还原

【Abstract】 High quality substrate material was eagerly needed in the heteroepitaxial growth process of diamond. In order to obtain highly oriented or single crystal diamond film, a kind of highly oriented or single crystal substrate should be designed. In the present work, a suitable structure was designed by the simulation method. And on the other hand, experiments of different deposition parameters were put on to prepare and characterize the multi-layers.By using the method of simulation and experiment respectively, related research of the designed structure and the prepared thin films was carried on.Materials Studio was used in the simulation part as a kind of analysis calculation software for materials, in order to explain why the iridium(Ir) is helpful for diamond heteroepitaxy growth and how Ti N transition layer plays a significant role for the entire structure. The Ti N, Mg O and Ti N/Mg O films were deposited by pulsed laser deposition(PLD) method at different conditions after that. Then, step profiler,scanning electron microscopy(SEM), atomic force microscopy(AFM), X-ray photoelectron spectroscopy(XPS), grazing incidence X-ray diffraction(GIXRD)and nano-mechanical systems(nanoindentation and nano-scratch) were used to characterize morphologies, roughness, bond and binding energy, structure and mechanical properties of the films.The multi-layers structure was designed according to the design guidelines of the substrate for hetero-epitaxial. The structure which was based on Si(100) and can achieve the purpose of hetero-epitaxial was composed of Si(100)/Ti N(100)/Mg O(100)/Ir(100). The performance of Ti N and Mg O ceramics was simulated by Materials Studio, as well as the combination of Mg O film on Si O2 or Ti N layers,indicating the presence of Ti N buffer layer between the Si substrate and Mg O film plays an important role in improving the binding properties because of the formation of chemically-as Ti-N-Mg-O bond. Meanwhile, the performance of carbon atoms on Si had also be simulated, to compare with that on iridium(Ir). No adsorption,dissolution and precipitation process was observed as that in Ir, which can obviously improve nucleation density of diamond and the quality of diamond film.In the pre-experiments, the performance of poly and single crystal diamond was compared, the suitable Ti N and Mg O targets for films deposition were perpared and characterized, and the clear Si substrate was obtained by a pre-oxidation cleaning process.Quasi-single crystal Ti N films and Mg O/Ti N stacks with atomically smooth surface(surface roughness average Ra <0.3 nm) and a highly(100) oriented wereprepared in the present work. The quality of the films was improved with the increase of the laser energy, substrate temperature and pulse frequency. Namely a smoother surface, a better binding properties between particles(with binding energy increases), a more highly preferentially oriented and the improvement of mechanical properties were gained. Moreover, the introduction of Ti N transition layer(or template) plays a significant role to improve preferentially orientation and deposition quality. When Mg O thin films were prepared on Si substrate directly, the films show a structure with both the Periclase and Magnesium Oxide phases, and the introduction of appropriate thickness of the Ti N layer can make Mg O thin films with only Periclase phase.It provides a possibility for the growth of high-quality diamond film as the smooth and highly oriented stack was obtained. And it can alse be found that for the preparation of thin films by pulsed laser deposition(PLD), the use of higher laser power, the substrate temperature and the laser pulse frequency, can significantly improve the quality of the film, the film under suitable conditions for preparing,found that the laser energy and the substrate temperature has a certain compensation performance, increase the laser energy to bring additional energy particles migrate to the surface of the substrate, the substrate temperature can supplement particles triggered by the lack of accumulation. At the same time, the structure of the interface of the film and the substrate and buffer layer were analyzed in combination,the interface characteristic diffraction peaks changes with the state of film composition and deposition varies, the epitaxial film characteristics can explain to some extent.更多还原