Elimination of Deep Levels in Thick SiC Epilayers by Thermal Oxidation and Proposal of the Analytical Model

Abstract

It has been clarified that Z1/2 center, a well known deep level as a lifetime killer, can be reduced to the concentration below 1011 cm-3 by thermal oxidation or C+ implantation plus Ar annealing. In this study, the authors investigate the trap-reduction phenomena systematically (experimentally), and propose a model to analyze the phenomena. Furthermore, prediction of the defect distributions is realized by solving a diffusion equation in accordance with the trap reduction model. This analytical model can explain almost all experimental data: oxidation-temperature dependence, oxidation-time dependence, and initial-Z1/2-concentration dependence of the defect reduction. Based on these results, the authors accomplish to eliminate the Z1/2 center to a depth of 100 μm in the sample with a relatively high initial-Z1/2-concentration of 1013 cm-3 by thermal oxidation at 1400°C for 16.5 h.