SEMICONDUCTOR DEVICES AND METHODS OF MAKING SAME

摘要

A composite structure (16) having a silicon carbide epitaxial layer is provided. The epitaxial layer includes at least four regions arranged vertically and defining respective interfaces, where each of the regions is characterized by a respective impurity concentration, where the impurity concentrations vary across each o f the interfaces, and where each of the impurity concentrations exceeds 1.times.10 17 cm-3 for at least one single impurity in all of the regions.