Patent ID: 8154048

Claim:
A diode comprising: an n type semiconductor silicon substrate having a top surface and a bottom surface; an n type semiconductor layer disposed on the top surface of the n type semiconductor silicon substrate; a p type polycrystalline silicon layer disposed on the n type semiconductor layer; a first electrode disposed on the p type polycrystalline silicon layer so as to be in contact with the p type polycrystalline silicon layer; a second electrode disposed on the bottom surface of the n type semiconductor substrate; an oxide film disposed between the n type semiconductor layer and the p type polycrystalline silicon layer so that the oxide film is in contact with the n type semiconductor layer and the entire bottom surface of the p type polycrystalline layer; and a high-concentration p type impurity region formed in a portion of the n type semiconductor layer that is below an edge portion of the p type polycrystalline silicon layer so as to have an impurity concentration higher than the p type polycrystalline silicon layer, wherein the oxide film is in contact with the high-concentration p type impurity region.