Papers by Keyword: Etch Pits

Abstract: A major crystalline defect which causes a pn junction reverse leakage current has been identified. A faintish stripe defect (FSD), the main cause of the leakage current, was observed in about 90% of the current leak points of our pn diodes. Double shell pits were observed at the edge of the FSD after molten KOH etching, indicating that the FSD is elongated on a basal plane and crosses the epilayer surface. The FSDs are sorted into several groups in terms of the shapes and arrangements of the etch pits. A cross-sectional TEM image of an FSD shows an eight-hold stacked structure, demonstrating that the defect contains a stacking fault. Etch pit observation after repetitive RIE of an epilayer revealed that FSDs originate both in threading dislocations in SiC substrates and from an SiC epitaxial growth process itself.

Abstract: The lateral expansion of thin homoepitaxial cantilevers from mesas has been used to produce areas of on-axis 4H-SiC completely free of dislocations. Cantilever expansion is influenced by the geometric shape and crystallographic orientation of the pregrowth mesa. In order to form larger areas of defect free silicon carbide (SiC), progressive coalescence must occur when adjoining cantilevers merge. The progressive coalescence is largely dictated by the shape and orientation of the pregrowth mesa. We report on refinements to the pregrowth mesa geometry and orientation that allows rapid initiation of cantilever growth and promotes progressive coalescence of merging cantilevers. These modifications to the pregrowth mesa geometry permit larger areas of defect free 4H-SiC to be realized.