Electronic Behavior ofWide-Gap Semiconductor and Devices

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SiC epilayrs grown by chemical vapor deposition were characterized by Hall effect, admittance spectroscopy , low-temperature photoluminescence, (PL) and deep level transient spectroscopy (DLTS).The background donor concentration of undoped epilayrs could be reduced down to 1*10^<14>cm^<-3> by increasing the C/Si ratio during growth. The nitrogen donor activation energies were estimated as 50meV at hexagonal and 110meV at cubic sites. In low-temperature PL,the nitrogen bound exciton peaks and free exciton peaks were dominant, indicating high-purity of epilayrs. DLTS measurements revealed a low concentration of electron traps (-10^<13>cm^<-3>). This trap can be created by the irradiation of any high-energy particles, and is stable even after high-temperature annealing at 1700ﾟC.From detailed analyzes of photoluminescence and DLTS peaks, this trap may originate from a Si-C divacancy.B and Al ion implantations into n-type SiC epilayrs were investigated. The critical implant dose for amorphization is estimated to be 1*10^<15>cm^<-2> for Al^+ implantation and 5*10^<15>cm^<-2> for B^+ implantation. By Al^+ implantation followed by annealing at 1500ﾟC,p-type epilayrs with a sheet resistance of 22kOMEGA/* could be obtained. B^+ implantation resulted in the formation of highly resistive layrs. This resistive layrs were successfully applied to the edge termination of high-voltage SiC Schottky rectifiers. Using this technique, 1.7kV SiC rectifiers with a very low on-resistance of 5mOMEGAcm^2 were realized.