Examination of in-grown stacking faults in 8°- and 4°-offcut 4H-SiC epitaxy by photoluminescence imaging

Thirty-six large, up to 3-inch-diameter, epitaxial 4H-SiC samples were mapped by photoluminescence imaging. In-grown stacking faults (IGSFs) for both 8 degrees- and 4 degrees-offcut were examined structurally and spectrally. Imaging at various spectral bands revealed different features for IGSFs. For the 8 degrees-offcut, IGSFs possessed two well-defined shapes, while for the 4 degrees-offcut IGSFs appear with a variety of shapes. The difference in IGSF formations between 8 degrees- and 4 degrees-offcut is currently unknown. Screw dislocations displaced the IGSF basal plane, producing line defects that possessed irregular intensity. Rough estimates of the IGSF density were performed over representative regions of the whole wafers with some wafers having < 1 cm(2) while others had >100 cm(-2). Most IGSFs (> 95%) originated at the epilayer/substrate interface, revealed by a small triangle in the buffer layer. Particles were responsible for the few IGSFs formed after the initial growth. The results suggested that pregrowth treatment and initial growth conditions were responsible for forming a majority of the IGSFs.