硼掺杂四面体非晶碳薄膜的光学特性研究

Investigation of the optical properties of boron doped tetrahedral amorphous carbon films

采用过滤阴极真空电弧技术制备了不同硼含量的掺杂四面体非晶碳薄膜(ta-C:B)。使用椭偏仪和紫外-可见光分度计测试了薄膜的折射率、消光系数、透过率和反射率。结果表明,硼含量小于2.13%时,硼含量增加,薄膜折射率缓慢增大;消光系数基本保持不变。当硼含量继续增加到3.51%和6.04%时,折射率分别迅速增加至2.65和2.71,相应的消光系数增大至0.092和0.154;而薄膜的光学带隙从2.29eV缓慢减小至1.97eV,后又迅速降至1.27eV。同时ta-C:B膜的透过率逐渐减小,反射率逐渐增大,表明硼的掺入降低了薄膜的透光性能。ta-C:B膜光学性能的变化,除了与sp3杂化碳的含量有关外,还取决于薄膜中sp2杂化碳的空间分布特点。

Boron doped tetrahedral amorphous carbon（ta-C..B） films with varying contents of boron,were prepared by a filtered cathodic vacuum arc system. The optical parameters such as refractive index, extinction coefficient, spectrum transmittance and reflectance were measured by spectroscopic ellipsometry and UV-Vis spectroscopy. With increasing the boron content in the ta-C.-B film from 0 to 2.13 at. % ,the refractive index was slowly increased,while the extinction coeffi- cient was little changed. As boron content continues to increase to 3.51 at.% and 6. 04 at. %, the refractive index increased quickly to 2. 65 and 2. 71 ,and the extinction coefficient changed to 0. 092 and 0. 154. And the band gap of ta-C： B wasde- creased slightly to 1.97eV first and decreased rapidly to1.27eV later 2.13. Meanwhile, the transmittance was reduced grad- ually, and the refractive index was increased gradually. Furthermore, the optical properties of ta-C..B film were largely de- termined by the distribution of spZ-hybridized carbon as well as spa bonding concentration.