Deep-level transient spectroscopy study on double implanted n(+)-p and p(+)-n 4H-SiC diodes

Planar n(+)-p and p(+)-n junction diodes, fabricated in 4H-SiC epitaxial layers using a double-implantation technology (a deep-range acceptor followed by a shallow-range donor implantation and vice versa), are characterized using capacitance deep-level transient spectroscopy (DLTS) to detect deep levels, which may influence device electrical performance. Either Al or B was used as the acceptor, while N or P was used as the donor, with all implants performed at 700 degreesC and annealed at 1600-1650 degreesC with an AlN protection cap. Different traps were observed for the various dopants, which are believed to be related to different impurity-defect complexes. A trap at similar toE(V)+0.51 eV was observed in nitrogen-implanted samples, while an acceptor trap at similar toE(V)+0.28 eV and a donor trap at similar toE(C)-0.42 eV were observed in Al-implanted samples. A prominent boron-related D-center trap at similar toE(V)+0.63 eV is seen in the DLTS spectra of B-implanted diodes. In diodes with implanted phosphorus, three traps at similar toE(V)+0.6 eV, E-V+0.7 eV, and E-V+0.92 eV, are seen, which are not observed for implantations of other species. (C) 2004 American Institute of Physics.