Temperature-dependent Raman property of n-type SiC

Abstract

Micro-Raman scattering from the nitrogen doped n-SiC is performed at the temperatures ranging from 100 to 450 K. The temperature dependences of the first-order Raman scattering, electronic Raman spectra and the second-order Raman features are obtained. These measurements reveal that most of the first-order Raman phonon frequencies decrease with temperature increasing, but the redshifts of the acoustic phonon modes are smaller than those of the optical phonon modes. Meanwhile, the longitudinal optical phonon-plasma coupled (LOPC) mode manifests different features with temperature increasing. The LOPC mode tends to have a blueshift at a lower temperature but a redshift at a higher temperature. This indicates that the temperature dependence of LOPC mode is affected not only by the anharmonic effects, but also by the ionized donor concentration. With the increase of the measurement temperature, the intensity of the electronic Raman spectrum decreases, and the linewidth gradually broadens, but the electronic Raman signal is almost not shifted. The redshift of the second-order Raman spectrum is smaller than that of the first-order Raman spectrum, but the intensity of the second-order Raman spectrum substantially decreases with the increase of temperature.