SiC外延层表面化学态的研究

用高分辨X射线光电子能谱仪(XPS)和傅里叶变换红外(FTIR)光谱仪研究了SiC外延层表面的组分结构. XPS宽扫描谱，红外掠反射吸收谱及红外镜面反射谱的解析结果说明SiC外延层表面是由Si—O—Si和Si—CH₂—Si聚合体构成的非晶SiC_xO_y:H. SiC外延层表面的化学态结构为Si(CH₂)₄，SiO(CH₂)₃，SiO₂(CH₃)₂，SiO₃(CH₃)，Si—Si,游离H₂O，缔合OH，Si—OH，O和O₂. 根据化学态结构和元素电负性确定了化学态的各原子芯电子束缚能顺序，并与XPS窄扫描谱拟合结果相对比，建立了化学态与其束缚能的对应关系，进而用Si(CH₂)₄的实际C 1s束缚能值进行校正，确定了各化学态的束缚能. 结果发现，除了SiC_xO_y(x=1,2,3,4，x+y=4)的Si 2p束缚能彼此不同外，其C 1s和O 1s彼此也不相同，其中SiO₂(CH₃)₂和SiO₃(CH₃)的C 1s束缚能与CH_m和C—O中C 1s的相近，对此从化学态结构，元素电负性和邻位效应进行了解释. 关键词： SiC 化学态 XPS FTIR

Study on the chemical states of the surface of SiC epilayer

In this paper, the composition structures of SiC epilayer surface are characterized by high resolution X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectrum. The results of XPS wide scan spectroscopy, infrared glancing reflection absorption spectrum and infrared specular reflection spectroscopy show that the amorphous phase SiC_xO_y:H is made up of Si-O-Si and Si-CH₂-Si polymers. The chemical state structures are composed of Si(CH₂)₄, SiO(CH₂)₃, SiO₂(CH₃)₂, SiO₃(CH₃), Si-Si, dissociative H₂O, combined OH，Si-OH, O and O₂. The order of the atom core electron binding energy values is determined by chemical state structures and element electronegativity. Compared with the XPS narrow scan spectrum fitting results, the corresponding relation between chemical states and its binding energies is established, and all chemical state binding energies are obtained using the calibration of C 1s binding energy of Si(CH₂)₄. The result shows that the C 1s and O 1s binding energy values of SiC_xO_4-x(x=1,2,3) are different from each other, similar as their Si 2p binding energies, of which the C 1s of SiO₂(CH₃)₂ and SiO₃(CH₃) are respectively close to those of CH_m and C—O. The reasonable explanation is presented in terms of chemical state structures, electronegativity and neighbouring site effects.