Thermal capacitance spectroscopy of epitaxial 3C and 6H-SiC pn junction diodes grown side by side on a 6H-SiC substrate

Abstract

The fabrication of 3C-SiC and 6H-SiC pn junction diodes, grown side by side on low-tilt-angle 6H-SiC substrates via a chemical vapor deposition (CVD) process, has recently been reported. Admittance spectroscopy and deep-level transient spectroscopy (DLTS) measurements were made on one of these diodes to compare the defect structure of 3C- and 6H-SiC CVD epitaxial layers grown under the same conditions. The 6H-SiC layers revealed a single minority carrier level and a deeper broad majority carrier peak. The minority level is due to the boron-related D center, whereas the broad majority level was identified as a double peak by a DLTS simulation. DLTS measurements on the 3C-SiC layers revealed only one deep level impurity consistent with the boron-related D center. Shallow donor levels observed using admittance spectroscopy correspond with the known shallow nitrogen donor in both 3C- and 6H-SiC epitaxial layers. This confirms that both 3C- and 6H-SiC polytypes were simultaneously formed on the same 6H-SiC substrate.