Observation of Crystalline Defects Causing pn Junction Reverse Leakage Current
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.
Akira Suzuki, Hajime Okumura, Tsunenobu Kimoto, Takashi Fuyuki, Kenji Fukuda and Shin-ichi Nishizawa
T. Watanabe et al., "Observation of Crystalline Defects Causing pn Junction Reverse Leakage Current ", Materials Science Forum, Vols. 600-603, pp. 999-1002, 2009