Temperature dependence of Raman scattering in bulk 4H-SiC with different carrier concentration

作者：Hua Yang Sun, Siou-Cheng Lien, Zhi Ren Qiu, Hong Chao Wang, Ting Mei, C. W. Liu, Zhe Chuan Feng · 发表于：Optics Express · 年份：2013 · DOI：10.1364/oe.21.026475 · 被引用次数：34 · 研究领域：Silicon Carbide Semiconductor Technologies、Thin-Film Transistor Technologies、Semiconductor materials and devices

Raman spectra of three bulk 4H-SiC wafers with different free carrier concentration were measured at temperature from 80 K to 873 K. As temperature increases, Raman peaks of most optical phonon modes show monotonous down shift. An anomalous non-monotonous variation with temperature, was observed in the A(1) longitudinal optical (LO) mode from doped samples. Two methods of theoretical fitting, one-mode (LO-plasma coupled (LOPC) mode) and two-mode (A(1)(LO) + LOPC) fitting, are employed to analyze this anomalous phenomenon. Theoretical simulations for temperature dependent Raman spectra by using two methods are critically examined. It turns out that one-mode method conforms well the experimental results, while two-mode method is untenable in physics. The non-monotonous variation of blue-red shifts with temperature for LOPC mode from doped 4H-SiC could be explained by the influence from ionization process of impurities on the process of Raman scattering. A quantitative description on temperature dependent Raman spectra for doped 4H-SiC is achieved, which matches well to experimental data.