Patent ID: 8106422

Claim:
An avalanche photodiode semiconductor device of the type for converting an impinging photon into an electrical current comprising: a base n+ doped substrate composed of a first material and having a window section where the base n+ doped substrate has been removed for passing the photon impinging on the avalanche photodiode device; a first n− doped layer of said first material formed on top of the base n+ doped substrate and having a portion of a lower surface suitably exposed through the window section for receiving the photon impinging on the avalanche photodiode device; a second upper n+ doped layer of said first material formed on the first n− doped layer with the first n− doped layer located between the base n+ doped substrate and the second upper n+ doped layer; a third epitaxially grown p+ doped layer of said first material formed on top of the second upper n+ doped layer such that the second upper n+ doped layer is formed sandwiched between the first n− doped layer and the third epitaxially grown p+ doped layer; a pair of conductive metal contacts; and, at least one planar floating guard ring formed below the third epitaxially grown p+ doped layer, separated from the third epitaxially grown p+ doped layer, and doped at a level that is different than that of the third epitaxially grown p+ doped layer, wherein a first contact is formed with the base n+ doped substrate and a second contact is formed with the third epitaxially grown p+ doped layer.