Orientation dependence of near-threshold damage production by electron irradiation of 4H SiC and diamond and outward migration of defects

Low temperature photoluminescence measurements have been made on samples of 4H SiC and diamond irradiated in different crystallographic directions with electrons having energies close to the atomic displacement thresholds. The defects produced in the 4H SiC are found to show some differences from those predicted by molecular dynamics calculations and possible reasons for the differences are discussed. The discussion refers to results from earlier as well as new experiments on the outward migration of defects during irradiation. The results for the energy dependence of the damage introduced into <1 0 0>, <1 1 0> and <1 1 1> oriented diamond are evaluated and shown to be consistent with theory.