Development of sensitive detection of crystalline defects in wide gap semiconductor by Raman scattering measurements

用背散射几何方法研究了含层错的3C，6H，4H-SiC晶体的拉曼光谱。结果表明，与3C-SiC的伽马点声子模对应的796 cm^&lt；-1&gt；处的横向光学声子带强度对层错很敏感。我们发现，该带的强度依赖于层错密度。根据键极化率模型对这些结果进行了解释。通过拉曼图像测量研究了层错的空间分布。通过对LO声子等离子体激元耦合模型的线形分析，确定了载流子浓度。研究了调制掺杂6H-碳化硅晶体中载流子浓度和迁移率的空间分布。我们的实验结果表明，拉曼微探针成像对于分析局域电学性质是有用的。我们还用拉曼探针测量了碳化硅陶瓷的多型相。由陶瓷中4H和15R多型相相对于6H相的折叠模的拉曼强度测得的体积分数与X射线衍射法测得的体积分数一致。我们可以用微米级的分辨率来研究多型区的空间分布与晶体颗粒之间的关系。

Raman spectra of 3C, 6H, 4H-SiC crystals including stacking faults have been examined using a backscattering geometry. It is found that the intensity of the transverse optical phonon band at 796 cm^<-1>, which corresponds to the phonon mode at the gamma point in 3C-SiC, is sensitive to the stacking faults. We found that the intensity of this band depends on the stacking fault density. These results are explained on the basis of the bond polarizability model. The spatial distribution of the stacking faults is studied by Raman image measurements. The carrier concentration is determined from the line shape analysis of the LO phonon plasmon coupled model. We evaluate the spatial distribution of the carrier concentration and the mobility for modulation-doped 6H-SiC crystals. Our experimental results demonstrate the Raman micro probe imaging is useful to analyze local electrical properties. We also evaluate the polytype phases of the SiC ceramics from Raman probe measurements. The volume contents measured by the Raman intensity of the folded modes of 4H and 15R polytype phases relative to that of the 6H phase in the ceramics are consistent with those determined from x-ray diffraction analysis. We can examine the relation between the spatial distributions of the polytype domains and crystalline grains with a resolution of micro-meter scale.