Detection and depth analyses of deep levels generated by ion implantation in n- and p-type 4H-SiC

The authors investigated deep levels in the whole energy range of bandgap of 4H-SiC, which are generated by low-dose N(+), P(+), and Al(+) implantation, by deep level transient spectroscopy (DLTS). Ne(+)-implanted samples have been also prepared to investigate the pure implantation damage. In the n-type as-grown material, the Z(1/2) (E(C)-0.63 eV) and EH(6/7) (E(C)-1.6 eV) centers are dominant deep levels. At least, seven peaks (IN1, IN3-IN6, IN8, and IN9) have emerged by implantation and annealing at 1000 degrees C in the DLTS spectra from all n-type samples, irrespective of the implanted species. After high-temperature annealing at 1700 degrees C, however, most DLTS peaks disappeared, and two peaks, IN3 and IN9, which may be assigned to Z(1/2) and EH(6/7), respectively, survive with a high concentration over the implanted atom concentration. In the p-type as-grown material, the D (E(V)+0.40 eV) and HK4 (E(V)+1.4 eV) centers are dominant. Two peaks (IP1 and IP3) have emerged by implantation and annealing at 1000 degrees C, and four traps IP2 (E(V)+0.39 eV), IP4 (E(V)+0.72 eV), IP7 (E(V)+1.3 eV), and IP8 (E(V)+1.4 eV) are dominant after annealing at 1700 degrees C in all p-type samples. The IP2 and IP8 may be assigned to the HS1 and HK4 centers, respectively. The depth analyses have revealed that the major deep levels are generated in the much deeper region than the implant profile.