Injection control in semiconductor power devices

A semiconductor power device, comprising:

• a substrate structure comprising a lightly doped semiconductor substrate of a first conductivity type or a second conductivity type opposite to the first conductivity type;
• a semiconductive first buffer layer of the first conductivity type formed above the lightly doped semiconductor substrate, wherein a doping concentration of the first buffer layer is greater than a doping concentration of the lightly doped semiconductor substrate;
• a semiconductive second buffer layer of the second conductivity type formed above the first buffer layer;
• and
• a semiconductive epitaxial layer of the second conductivity type formed above the second buffer layer, wherein a doping concentration of the epitaxial layer is greater than a doping concentration of the second buffer layer;
• and
• one or more semiconductor power device structures formed at a top side of the substrate structure.

A method, comprising:

• forming a substrate structure comprising a lightly doped semiconductor substrate of a first conductivity type or a second conductivity type opposite to the first conductivity type;
• forming a semiconductive first buffer layer of the first conductivity type above the lightly doped semiconductor substrate, wherein a doping concentration of the first buffer layer is greater than a doping concentration of the lightly doped semiconductor substrate;
• forming a semiconductive second buffer layer of the second conductivity type above the first buffer layer;
• and
• forming a semiconductive epitaxial layer of the second conductivity type above the second buffer layer, wherein a doping concentration of the epitaxial layer is greater than a doping concentration of the second buffer layer.