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【答案】应助回帖
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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
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
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.
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