US Patent 7868406 Photodiode being monolithically integrated onto a waveguide

A waveguide-integrated photodiode for high bandwidths with a semi-insulating monomode supply waveguide monolithically integrated on a substrate, together with an overlying photodiode mesa structure having an electroconducting n-contact layer, an absorption layer, a p+-contact layer and a metallic p-contact, the refraction index of the n-contact layer being greater than the refraction index of the semi-insulating waveguide layer. Lengthening the n-contact layer by a predetermined length L in the direction of the supply waveguide in relation to the overlying layers correspondingly increases at least one factor of the product of quantum efficiency and bandwidth.