Study of V and Y shape Frank-type Stacking Faults Formation in 4H-SiC epilayer

Nomarski optical microscopic,KOH etching and Synchrotron Topographic studies are presented of faint needle-like surface morphological features in 4H-SiC homoepitaxial layers. Grazing incidence synchrotron white beam x-ray topographs show V shaped features which transmission topographs reveal to enclose 1/4[0001] Frank-type stacking faults. Some of these V-shaped features have a "tail" associated with them and are referred to as Y-shaped defects. Geometric analysis of the size and shape of the V-shaped faults indicates that they are fully contained within the epilayer and appear to be nucleated at the substrate/epilayer interface. Detailed analysis shows that the apex positions of the V-shaped stacking faults match with the positions of c-axis threading dislocations with Burgers vectors of c or c+a simultaneously nucleated in the epilayerSimilarly, the Y-shaped defects match well with the substrate surface intersections of c-axis threading dislocations with Burgers vectors of c or c+a in the substrate which were deflected onto the basal plane during substrate growth. Based on the observed morphology of these defect configurations we propose a model for their formation mechanism.