Temperature-dependent Raman scattering in round pit of 4H-SiC

The Raman spectra of N-doped 4H-SiC single crystal films is investigated between 100 and 600 K. The temperature dependence of the three optical modes is obtained. These measurements reveal that all Raman peaks shift to lower frequencies with increasing temperature, except A₁(LO). The temperature dependence of A₁(LO) phonon modes in the round pit also manifests different features with temperature increasing, but the demarcation temperature point of the blueshift and the redshift in the round pit is higher than that in the outer area. At high temperature, all active phonon modes clearly become broader, but the linewidth of the E₁(TO) phonon mode from round pit increases with temperature more rapidly than that from the outer area, this indicates that the lifetime of the E₁(TO) phonon in round pit is more sensitive than that in the outer area.