Patent ID: 7977713

Claim:
A semiconductor device comprising: a substrate layer of a semiconductor material of a first conductivity type; a first layer of a semiconductor material of the first conductivity type on the substrate layer; a raised region of a semiconductor material of the first conductivity type on the first layer, the raised region comprising an upper surface and first and second sidewalls, wherein the first and second sidewalls are tapered such that the raised region is narrower near the upper surface than adjacent the first layer; semiconductor material of a second conductivity type different than the first conductivity type on the first and second sidewalls of the raised region and on the upper surface of the first layer adjacent to the raised region; and a third layer of a semiconductor material of the first conductivity type on the upper surface of the raised region; wherein the raised region comprises a first portion with a first average dopant concentration of dopants of the first conductivity type adjacent the third layer and a second portion with a second average dopant concentration of dopants of the first conductivity type between the first portion and the first layer, wherein the first average dopant concentration is lower than the second average dopant concentration and wherein the second average dopant concentration is higher than the average dopant concentration of the first layer.