Semiconductor device and method of making thereof

A field effect transistor (FET) semiconductor device, comprising:

• a first layer having a first conductivity type that forms a drift region of the FET semiconductor device;
• a second layer disposed directly atop the first layer, the second layer having the first conductivity type, wherein a dopant concentration profile of an average dopant concentration within the second layer as measured from a surface of the second layer to a first depth of the second layer comprises a retrograde profile;
• a laterally graded and segmented termination region formed in the second layer, the termination region having a second conductivity type opposite the first type, wherein the average dopant concentration of the second layer is greater than an average dopant concentration of the first layer;
• and
• an active region at least partially formed in the second layer, wherein the active region comprises a well region that is contiguous with a first lateral side of the termination region and wherein the second layer is contiguous with a second lateral side of the termination region opposite the first side.

A silicon carbide (SiC) field effect transistor (FET) device comprising:

• a first layer having a first conductivity type that forms a drift region of the SiC FET device;
• a second layer disposed directly atop the first layer, the second layer having the first conductivity type, wherein a dopant concentration profile of an average dopant concentration within the second layer as measured from a surface of the second layer to a first depth of the second layer comprises a retrograde profile;
• a termination region formed in the second layer, the termination region having a second conductivity type opposite the first type;
• and
• an active region at least partially formed in the second layer, wherein the active region comprises a well region that is contiguous with a first lateral side of the termination region, and wherein the second layer is contiguous with a second lateral side of the termination region opposite the first side.