Study on the Structure of the Unpaired Electron in Diamond Films and Trials to Reduce the Unpaired Electron

研究了金刚石薄膜中的顺磁缺陷密度随晶粒取向的变化规律。采用偏压辅助微波CVD方法，以甲烷、二氧化碳和氢气为原料，在硅（100）衬底上沉积了具有不同形貌的（100）取向金刚石薄膜。为了获得高度取向的薄膜，有必要通过渗碳和偏压增强成核（BEN）在硅衬底上形成检查的纳米图案。然而，这些过程的细节并不为人所知。通过调节微波功率、甲烷浓度、预处理时间、气体压力和偏压等工艺参数，形成了纳米图形。评价在纳米图案上生长的金刚石膜的质量，并获得以下结果。(1)为了形成清晰的纳米图案，微波功率、气压、处理时间和偏压是重要的参数。(2)为了改善金刚石的（100）取向，纳米图案的清晰化是必要的，但是通过长时间的BEN处理，过度的清晰化导致取向恶化。(3)预处理后的金刚石生长更好，如果使用甲烷和氢气，而不添加二氧化碳。(4)薄膜中的顺磁缺陷除H1心外还有两种心。(5)即使<18><-3>在通过优化图案形成和金刚石生长工艺制备的膜中，也存在密度为10 μ cm-3的顺磁缺陷。这是由于薄膜中残留的各种应力造成的。(6)在加入CO2的薄膜中发现了新的ESR中心。

We studied how does the density of paramagnetic defect in diamond films change, when they are composed of oriented crystal grains. (100)-oriented diamond films having various morphology were deposited on silicon (100) substrates from a mixture of methane, carbon dioxide and hydrogen using bias-assisted microwave CVD method. To obtain highly oriented films, it is necessary to form a checked nano-pattern on the silicon substrate by carburization and bias-enhanced nucleation (BEN). The detail of these processes, however, is not well known. We formed the nano-pattern by adjusting process parameters such as the microwave power, the methane concentration, the pretreatment time, the gas pressure and the bias voltage. Quality of the diamond films grown on the nano-patterns was evaluated, and the following results were obtained.(1) The microwave power, the gas pressure, the treatment time and the bias voltage are important parameters in order to form a clear nano-pattern.(2) To make clear the nano-pattern is necessary for improving the (100) orientation of diamond, but an excessive clearness by prolonged BEN treatment results in deterioration for the orientation.(3) Diamond growth after the pretreatment is better if methane and hydrogen is used without adding carbon dioxide.(4) There are two kinds of center in addition to the H1 center as for paramagnetic defect in the film.(5) There is paramagnetic defect of a density of 10^<18> cm^<-3>, even in the film prepared by optimizing the pattern formation and diamond growth process. This results from the remaining of various stress in the film.(6) A new ESR center is found in the film prepared by adding carbon dioxide.