含氮氟化类金刚石(FN-DLC)薄膜的研究:(Ⅱ)射频功率对薄膜光学带隙的影响

Study on FN-DLC thin films:(Ⅱ)effect of radio frequency power on the optical band gap of the thin films

以CF4,CH4和N2为源气体,采用射频等离子体增强化学气相沉积法,在不同射频功率下制备了含氮氟化类金刚石薄膜样品.原子力显微形貌显示,低功率下沉积样品表面致密均匀.拉曼及傅里叶变换红外光谱分析显示,随着射频功率的改变,薄膜的结构和组分也随之变化.紫外-可见光透射光谱证明薄膜具有紫外强吸收特性,通过计算得到其光学带隙在1.89—2.29eV之间.结果表明,射频功率增加,薄膜内sp2C含量增加,或者说CC交联相对浓度增加、F的相对浓度降低,导致薄膜内π-π*带边态密度增大,光学带隙的减小.

Nitrogen doped fluorinated diamond-like carbon （FN-DLC） thin films is deposited using radio frequency plasma enhanced chemical vapor deposition under different radio-freqtuency power with CF4, CH4 and N2 as source gases. Atomic force microscope （AFM） images show that the surface morphology of the films deposited at lower power is compact and uniform. The Raman and FTIR spectra show that the structure and composition of the films change with the radio-frequency power. The ultraviolet-visible （UV-VIS） spectrum shows that UV absorption is very strong in the films, and its optical band gap ranges from 1.89 to 2.29eV. As a result, when the power increases, the sp^2C content increases. That is, the concentration of C =C increases and the concentration of F drops. The density of state near band edgz of π-π^＊ increases, and the optical band gap becomes narrower.