High-resolution X-ray diffraction and optical absorption study of heavily nitrogen-doped 4H–SiC crystals

Abstract

Lattice parameter and optical absorption spectra were measured on heavily nitrogen-doped bulk crystals and epilayers of 4H–SiC. The rate of c-lattice parameter change versus doping concentration in high quality material was less than −3.6×10 −25 Å cm 3. In crystals containing high density of double stacking faults, the (0 0 0 8) X-ray reflection shifted toward the (2 2 2) reflection in 3C–SiC. Optical absorption measurements in such crystals detected peak at 3.1 eV similar to that reported in 3C–SiC with concomitant decrease of free carrier peak characteristic of 4H–SiC polytype.