Semiconductor devices and methods of making same

摘要

A composite structure 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 of the interfaces, and where each of the impurity concentrations exceeds 1x10¹⁷ cm^-3 for at least one single impurity in all of the regions.