Characterization of dislocation etch pits by molten KOH etching in n- and p-type 4H–SiC epilayers doped by ion implantation

Abstract

Dislocation etch pits by molten KOH etching in 4H–SiC epilayers doped by ion implantation have been characterized in this work. The sizes and shapes of dislocation etch pits are studied in an implanted nitrogen concentration range from 2 × 1019 cm−3 to 4 × 1019 cm−3 and an implanted aluminum concentration range from 1 × 1018 cm−3 to 1 × 1019 cm−3. It has been found that the etch rates at dislocations follow a trend of n+ < n− < p− ≈ p + while in all samples the threading dislocation etch pits show the anisotropic etching characteristic of hexagonal shape. Characteristics of dislocation etch pits in n + -4H–SiC samples are analyzed based on the effect of preferential N occupation at dislocations.