Effect of nitrogen addition on the microstructure and mechanical properties of diamond films grown using high-methane concentrations
Effect of nitrogen addition on the microstructure and mechanical properties of diamond films grown using high-methane concentrations
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DOI：
10.1063/1.370787
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发表时间：
1999-07-01
影响因子：
3.2
通讯作者：
Vohra, YK
中科院分区：
文献类型：
--
作者：
Catledge, SA;Vohra, YK
我们报道了在等离子体中添加不同的氮元素对金刚石薄膜的微观结构和力学性能的影响。等离子体中的甲烷含量为15%(氢气)，工作压力为125Torr。通过固定CH4流量和只改变N-2流量，在N-2/CH4比从0到0.30的范围内生长薄膜。随着氮掺杂的增加，拉曼光谱在1550 cm(-1)处的强度增加，半高宽减小，而在1332 cm(-1)处的晶体金刚石峰强度降低，半高宽增加。X-射线衍射仪分析表明，当N-2/CH4摩尔比为0.10时，随着氮气加入量的增加，薄膜的结晶度和金刚石颗粒尺寸迅速减小，但当氮气加入量超过该摩尔比时，薄膜结晶度和金刚石颗粒尺寸变化不大。薄膜表面粗糙度也有类似的趋势。此外，我们通过压痕测试发现，所有的薄膜都具有70~90 Gpa的高硬度，并且薄膜的韧性随着氮气加入量的增加而提高。光学发射光谱表明，等离子体中CN物种相对于C-2的增加是形成四面体无定形碳的原因(由1550 cm(-1)的拉曼光谱指示)。(C)1999年美国物理研究所。[S0021-8979(99)05313-X]。
We report on the microstructure and mechanical properties of diamond films grown using varying nitrogen additions to a plasma with a high-CH4 fraction of 15% (in hydrogen) and an operating pressure of 125 Torr. Films were grown at N-2/CH4 ratios ranging from 0 to 0.30 by fixing the CH4 flow rate and changing only the N-2 flow rate. With increasing nitrogen addition, we observe an increase in intensity and a decrease in the full width at half maximum (FWHM) of the Raman band at 1550 cm(-1), while the crystalline diamond peak at 1332 cm(-1) decreases in intensity and increases in the FWHM. X-ray diffraction confirms that the film crystallinity and diamond grain size decrease rapidly with increasing nitrogen additions up to a N-2/CH4 ratio of 0.10, but then do not change significantly above this ratio. A similar trend is observed for film surface roughness. In addition, we find from indentation testing that all films exhibit high hardness values ranging from 70 to 90 GPa and that the toughness of the films improves with increasing nitrogen addition. Optical emission spectroscopy reveals that an increase in CN species relative to C-2 in the plasma is responsible for the formation of tetrahedral amorphous carbon (indicated by the Raman band at 1550 cm(-1)). (C) 1999 American Institute of Physics. [S0021-8979(99)05313-X].