The Spatial Distribution of Defects and Its Dependence on Seed Polarity and Off-Orientation during Growth of 4H-SiC Single Crystals

The defect distribution in 4H-SiC single crystals in dependence on the seed polarity and its off-orientation was investigated by KOH-etching, optical microscopy and X-ray topography. Micropipe density, stacking fault density and dislocation density were determined for 2” crystals grown in <000-1> direction 0 - 7° off towards <11-20> and for crystals up to 1” in diameter grown in <11-20> or a- and <1-100> or m-directions and using repeated a-face growth. For the growth in polar directions the micropipe density and dislocation density decrease with increasing offorientation of the seed. A similar behavior was found for the stacking fault density and dislocation density in non-polar directions with off-orientation to c-direction. Nevertheless, while the dislocation density could be reduced up to three orders of magnitude for the growth along non-polar directions, the stacking fault density was continuously increasing. Additionally, the defect distribution after repeated a-face growth will be discussed in terms of growth related and kinetic models.