Infrared reflectance study of 3C-SiC epilayers grown on silicon substrates

We measure the infrared reflectance spectra of 3C-SiC epilayers on silicon substrates from 400 to 4000 cm(-1). An ideal model assuming smooth interfaces and a modified model containing an interfacial conducting layer and Gaussian rough interfaces are separately used for fits of the measured spectra. Although the fitted curve generated by the ideal model can basically agree with the measured one, it fails to reproduce some unusual spectral features. Instead, good fits are obtained by the modified model, from which the epilayer thicknesses, carrier concentrations, surface and interface roughnesses, and the information on the conducting layer are obtained. In comparison with scanning electron microscopy (SEM) results, we show that the infrared reflectance method can precisely determine the epilayer thicknesses. The estimated surface roughnesses are confirmed by atomic force microscopy measurements. The infrared reflectance analyses and SEM observations show that the interfacial roughness and conducting layer are related to the carbonization process. These results indicate that the infrared reflectance technique provides a nondestructive and fast method to evaluate 3C-SiC epilayers and then improve the epitaxial growth process.