Dislocation analysis of 4H-and 6H-SiC single crystals using micro-Raman spectroscopy

Micro-Raman spectroscopy is an excellent non-destructive analysis method, which compensates for disadvantages of KOH method. Raman shifts of A(1)(LO) and E-1(TO) band paeks at threading screw dislocation(TSD) were investigated in n-type on/off-axis 4H- and 6H-SiC single crystal wafers by micro-Raman scattering at room temperature. The results showed that A(1)(LO) band were shifted toward higher frequency while the E-1(TO) band were shifted toward lower frequency on the on-axis wafers. The shifts are caused by increasing electron concentration and lattice disorder near the dislocation core, respectively. In the off-axis wafer, no shift was observed possibly due to the measurement geometry which does not contain whole dislocation core.