Depth profiles of deep levels generated in the tail region of Al ion implantation into n-type 4H-SiC

Abstract

Depth profiles of deep levels in the tail region of Al ion implantation in n-type 4H-SiC were investigated by deep level transient spectroscopy measurements. Deep levels energetically located at Ec – 0.55 eV, Ec – 0.64 eV, and Ec – 1.50 eV (Ec : conduction band bottom) are generated in the tail region by the implantation and subsequent activation annealing at 1750oC for 20 min. The densities of these defects were approximately 20–40 times lower than the implanted Al atom density, and the densities of these defects and Al atoms exhibited an exponential decay along the depth direction with a decay length of 140–190 nm. Another deep level located at Ec – 1.30 eV was detected in the tail region and the density of this trap decreased more rapidly with a decay length of 62 nm. The origins of the observed deep levels are discussed based on several experimental results.