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利用两种不同激发波长进行 Ram an测量 ,研究了低碳含量 a- Si1 - x Cx∶ H (～ <2 0 at.% )薄膜的结构特征 .采用 6 47.1nm激发时 ,由于激发光能量接近于各样品的光学带隙 ,因而在样品中具有较大的穿透深度 ;而采用488nm激发时 ,激发光被样品表面强烈吸收 .探测深度的变化造成了两种激发下 Raman谱出现较大的差异 .实验结果表明样品体内存在硅团簇结构 ,样品的自由表面存在一层高浓度的缺陷层 .这两种空间的不均匀性造成了高能激发时 Raman谱的 TO模频率和半高宽比低能激发时有大的红移和展宽 .以上结果证明不同激发波长将造成Ram an测量结果的差异 .
The structure characteristics of a-Si1-x Cx:H (~ <2 0 at.%) Thin films with low carbon content were investigated by Raman measurements at two different excitation wavelengths. When using a 6 47.1 nm excitation, The optical bandgap of each sample has a larger penetration depth in the sample and the excitation light is strongly absorbed by the sample surface at 488 nm excitation.The variation of the probe depth results in a large Raman spectrum Difference.The experimental results show that there is silicon cluster structure in the sample, there is a high concentration of defect layer on the free surface of the sample.The inhomogeneity of these two kinds of space caused the TO mode frequency and half-width ratio Large-scale redshift and broadening of low-energy excitation are provoked by the above results, which demonstrate that the different excitation wavelengths will result in differences in Ram’s measurements.