Patent ID: 8274128

Claim:
A device comprising: a first semiconductor layer having a first concentration of dopant of a first type; a second semiconductor layer, disposed on the first semiconductor layer, and having a graded concentration of dopant of the first type; a third semiconductor layer, disposed on the second semiconductor layer opposite the first semiconductor layer, and having a second concentration of dopant of the first type that is less than the first concentration of dopant, wherein the graded concentration of the second semiconductor layer is between the first concentration of dopant and the second concentration of dopant, wherein the width of second semiconductor layer is between ten and forty five percent of the width of the third semiconductor layer, wherein the doping profile of the second semiconductor layer has a concentration approximately equal to the doping concentration in the third semiconductor layer proximate the third semiconductor layer, and wherein the doping concentration of the second semiconductor layer is between five and twenty times greater than the doping concentration of the third semiconductor layer proximate the first semiconductor layer; a guard region, disposed in the third semiconductor layer opposite the second semiconductor layer, and having a concentration of dopant of a second type, wherein the width and smooth doping profile of the second semiconductor layer reduces an electric field proximate the guard region; and a first metal layer, disposed on the third semiconductor layer opposite the second semiconductor layer proximate the guard region and forming a Schottky junction with the third semiconductor layer.