A series of cubic SiC single crystals were heteroepitaxially grown by the hot-wall chemical vapor deposition (CVD) using a HMDS-C3H8-H2 system on 2 inch silicon substrates with the orientations of (100), (111), (110) ...A series of cubic SiC single crystals were heteroepitaxially grown by the hot-wall chemical vapor deposition (CVD) using a HMDS-C3H8-H2 system on 2 inch silicon substrates with the orientations of (100), (111), (110) and (211), respectively. Even though an initial carbonization was carried out to reduce the large lattice mismatch, residual stress could not be completely relieved, partly also due to the difference of their thermal expansion coefficients. Raman scattering studies for the specimens were performed to estimate the internal stress in the SiC epilayer and the substrate. Raman spectra were mapped out on the sample surface as well as on the cross section using an automated x-y stage with a spatial resolution capable of 100 nm. For all the samples, two Raman peaks corresponding to the transverse optical (TO) and longitudinal optical (LO) phonon modes were observed, even though the intensity varied with the polarization configurations. In the SiC epilayers, tensile stresses decrease away from the interface, while compressive stresses exist in the substrate, with the magnitudes dependent on the growth orientation. The lattice strains were discussed in terms of the elastic deformation theory for the comparison.展开更多
文摘A series of cubic SiC single crystals were heteroepitaxially grown by the hot-wall chemical vapor deposition (CVD) using a HMDS-C3H8-H2 system on 2 inch silicon substrates with the orientations of (100), (111), (110) and (211), respectively. Even though an initial carbonization was carried out to reduce the large lattice mismatch, residual stress could not be completely relieved, partly also due to the difference of their thermal expansion coefficients. Raman scattering studies for the specimens were performed to estimate the internal stress in the SiC epilayer and the substrate. Raman spectra were mapped out on the sample surface as well as on the cross section using an automated x-y stage with a spatial resolution capable of 100 nm. For all the samples, two Raman peaks corresponding to the transverse optical (TO) and longitudinal optical (LO) phonon modes were observed, even though the intensity varied with the polarization configurations. In the SiC epilayers, tensile stresses decrease away from the interface, while compressive stresses exist in the substrate, with the magnitudes dependent on the growth orientation. The lattice strains were discussed in terms of the elastic deformation theory for the comparison.
