金刚石自支撑膜拉曼光谱1420cm^(-1)特征峰研究

Research on 1420 cm^(-1) Characteristic Peak of Free-standing Diamond Films in Raman Spectrum

采用带有半封闭式气体循环系统的100千瓦级直流电弧等离子体喷射CVD设备制备三组不同质量的金刚石膜,通过532 nm激光激发金刚石膜的拉曼光谱时,除1332 cm-1金刚石一阶拉曼峰外还出现了1420 cm-1宽峰,本文针对这一峰位的由来及分布进行研究。结果表明,增加或降低拉曼激发波长该峰为都不复存在,不符合材料的拉曼特征频移与激发波长无关这一原则,证明其并非本征拉曼峰;采用488 nm激发和514 nm激发时拉曼光谱分别出现了与1420 cm-1峰型一致的3125 cm-1和2060 cm-1峰,将拉曼频移转换为波长后发现,三个峰位都对应于波长575 nm(2.156e V);575 nm为金刚石膜荧光光谱中常见峰位,对应于氮杂质相关的[N-V]0中心,这表明含氮杂质金刚石膜采用532nm激发时产生的1420 cm-1峰是[N-V]0相关的氮杂质引起的荧光峰;采用532 nm对金刚石膜形核面和生长面的拉曼面扫描结果表明,[N-V]0相关的氮杂质存在于金刚石膜表面晶粒与晶界各处,并存在一定程度的偏聚。

Diamond films with different qualities were prepared by 100 k W high power DC arc plasma jet CVD operating at gas recycling mode. Besides the first-order diamond Raman peak at 1332 cm-1,a broad peak around1420 cm-1was appeared in Raman spectra of diamond films when excited using 532 nm wavelength. The origin and distribution of 1420 cm-1peak was researched. The results show that the peak 1420 cm-1vanishes whether increasing or decreasing the excitation wavelengths,which indicate that it is not an intrinsic Raman peak. The2060 cm^-1and 3125 cm^-1peaks,whose shapes are consistent with that of 1420 cm^-1,occur when excited using 488 nm and 514 nm wavelengths,respectively. These three peaks are all corresponding to 575 nm（ 2. 156 e V） after converting the Raman shift to wavelength. 575 nm peak is a common fluorescence peak which is attribute to the[N-V]0center in diamond films. It indicates that the 1420 cm^-1peak appears in Raman spectrum excited using532 nm is a [N-V]0related fluorescence peak. The using 532 nm Raman maps of the diamond films show that the[N-V]0related nitrogen impurity is distributed throughout the grains and boundaries,showing a certain degree of segregation.