Examination of two p-type 4H SiC samples having similar resistivity but very different radiation damage and annealing characteristics

In the course of studying by low temperature photoluminescence spectroscopy a wide range of electron-irradiated samples of p(Al)-type epitaxial layers of 4H SiC, from a variety of different sources of supply, the results were found to fit into two very different categories. The origin of these differences has been explored using a wide range of experimental techniques and found to result from the degree of compensation of the aluminium by nitrogen in the layers. Nitrogen concentrations deduced by SIMS experiments on these materials were found to be unreliable. The two different categories of material, called V and AB here, showed marked differences in their subsequent annealing behaviour and the implications of this distinction are discussed.