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形核是金刚石薄膜生长过程中必不可少的过程，形核密度的大小随着甲烷浓度的高低而发生变化，甲烷浓度越高，形核密度越高。甲烷浓度高，等离子体激发的碳源浓度越高，在基片表面的形核驱动力就越大。 在生长薄膜之前，选用不同的参数进行形核，在整个形核过程中，保持各自的H2和CH4浓度比不变，其中一组的浓度比为200:4，另外一组的浓度比为200:6，两个样品所不同的是通入反应中的CH4流量的大小。在20min后，形核过程结束，改变CH4浓度进行生长，并在生长过程中，在两组样品中都加入一定量的O2。 上图是形核时间20min的两个样品进行SEM表征图，由图中可以看到，两个样品的形核密度有所不同，图4b中的形核密度比图4a中的形核密度要高，这是因为图b中的样品在进行预处理的时候，采用的纳米级金刚石微粉进行研磨，使Si片表面有明显的划痕沟道，增加了C原子在Si表面的附着力，当气体进一步被激发之后，激发的C原子进一步堆积在沟道处，所生成的金刚石颗粒进一步增大，使得所生成的金刚石颗粒可以清晰的从SEM图中观察出来。从图4a中可以看到，在基底Si的表面有明显的划痕，并且沉积出的金刚石颗粒填充在划痕沟道中，从SEM图中可以观察到，基片表面还有部分地方不能看到清晰的金刚石颗粒，可能原因是这些区域的Si表面过于光滑，C原子不能有效的附着在其表面，另一个可能是由于所产生的C浓度相对较低，所生长出的颗粒较小，在当前的放大倍数下不能观察到。在基片的中心位子，可以看到部分颗粒已经连接成薄膜了，在后续生长的过程中，这部分的薄膜将优先生长，这可能导致这部分区域生长速率快于其它区域。 |
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luo27xiao
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RXMCDM: 金币+1, 多谢应助！ 2014-01-15 10:16:29
单子枫(RXMCDM代发): 金币+30, 多谢应助！ 2014-01-26 15:54:25
单子枫(RXMCDM代发): 金币+30 2014-01-26 15:54:31
单子枫(RXMCDM代发): 金币+30 2014-01-26 15:54:38
RXMCDM: 金币+1, 多谢应助！ 2014-01-15 10:16:29
单子枫(RXMCDM代发): 金币+30, 多谢应助！ 2014-01-26 15:54:25
单子枫(RXMCDM代发): 金币+30 2014-01-26 15:54:31
单子枫(RXMCDM代发): 金币+30 2014-01-26 15:54:38
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Nucleation of diamond film growth process is essential to the process, the size of the nucleation density with low methane concentrations and changes, the higher the methane concentration, the higher the nucleation density. High methane concentration, the higher the concentration of carbon plasma excitation, the driving force in the nucleation substrate surface becomes. Before film growth, the use of different parameters of nucleation in the nucleation process, H2 and CH4 to maintain their constant concentration ratio, wherein a concentration ratio of 200:4, and the other group concentration ratio of 200 : 6, two samples of different size are introduced into the reaction of CH4 flow. 20min after the nucleation process ends, the CH4 concentration changes were grown in the growth process, the two samples are added in an amount of O2. The figure is the nucleation time of the two samples were analyzed by SEM FIG 20min, can be seen from the figure, the nucleation density of two samples different in Figure 4b than the nucleation density of the nucleation density to Figure 4a high, because the sample in b during preprocessing when using nano-diamond powder grinding, the Si substrate surface scratches channel significantly increases the adhesion of C atoms in the Si surface, when Further, after the gas is excited, the C atoms excited in the channel of the further accumulation, the resulting diamond particles is further increased, so that the diamond particles are generated can be clearly observed from the SEM figure. As can be seen in Figure 4a, the surface of the Si substrate has a noticeable scratches, and the deposition of diamond particles filling the channel in the scratches, it can be observed from the SEM images, there are some parts of the substrate surface can not be seen clear diamond particles, probably because the surfaces of the Si region is too smooth, C atoms which can not be effectively attached to the surface, and the other may be generated by the C content is relatively low due to the smaller particles grow born in the current the magnification can not be observed. In the center seat of the substrate, can see some of the particles into a film has been connected, the subsequent growth process, the film which will be part of the preferential growth, which may result in faster growth rate of this part of the region to other regions |
2楼2014-01-11 18:27:22
deng神之刺客
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RXMCDM: 金币+1, 多谢应助！ 2014-01-15 10:16:41
单子枫(RXMCDM代发): 金币+30, 最佳答案！ 2014-01-26 15:53:05
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RXMCDM: 翻译EPI+1 2014-01-26 18:43:20
RXMCDM: 金币+1, 多谢应助！ 2014-01-15 10:16:41
单子枫(RXMCDM代发): 金币+30, 最佳答案！ 2014-01-26 15:53:05
单子枫(RXMCDM代发): 金币+30 2014-01-26 15:53:16
单子枫(RXMCDM代发): 金币+30 2014-01-26 15:53:22
单子枫(RXMCDM代发): 金币+30 2014-01-26 15:53:29
单子枫(RXMCDM代发): 金币+30 2014-01-26 15:53:35
单子枫(RXMCDM代发): 金币+30 2014-01-26 15:53:41
单子枫(RXMCDM代发): 金币+20 2014-01-26 15:53:47
RXMCDM: 翻译EPI+1 2014-01-26 18:43:20
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Nucleation is an indispensable procedure in the process of diamond film growth, the size of the nucleation density along with the change of methane concentration. The higher the methane concentration , the higher the nucleation density. With the high concentration of methane, the higher the concentration of carbon excitated by plasma, the greater the nucleation driving force on the surface of the substrate. Before the growth of film, different parameters of nucleation was chosen, in the whole process of the nucleation, maintained their respective H2 and CH4 concentration ratio unchanged, the concentration ratio of one group was 200:4, another group was 200:6, the difference of two samples was that the size of the CH4 flow rate was different in the reaction. 20 min after the end of the nucleation process, change the concentration of CH4 in growth, and the two samples were added in a certain amount of O2 in the process of growth. The figure above was when the nucleation time was 20 min, the two samples were analyzed by SEM FIG. It could be seen in the figure that the nucleation density of two samples were different. In figure 4b nucleation density was higher than that in figure 4a, this was because in the pretreatment of the sample in figure b, adoptive of nanoscale diamond fine powder was grinded, so obvious scratch channel was generated on the Si substrate surface, increased the adhesion of C atoms in the Si surface. When the gas was further excited, C atoms excited in the channel of the further stacked, the generated diamond particles increased further, so that the diamond particles were generated could be clearly observed from the SEM figure. As could be seen in Figure 4a , there was a noticeable scratches on the surface of the Si substrate, and the deposition of diamond particles filled in the channel scratches. It could be observed from the SEM images, diamond particles could not be seen clearly on some parts of the substrate surface, possible reason was that these areas of the surface of the Si was so smooth that C atoms could not be attached to the surface effectively; another reason might be that the C concentration was relatively low, the growth of particles was small, and it could not be observed under the current magnification. In the center seat of the substrate, it could be seen part of the particles had been connected into film. This part of the film would given priority to grow in the subsequent growth in the process, which might lead to this part of the regional growth rate faster than the other. 供参考 |
3楼2014-01-12 19:52:11
