Abstract: A PIN photodetector includes a first semiconductor contact layer, a semiconductor absorption layer having a larger area than the first semiconductor contact layer, a semiconductor passivation layer positioned between the first semiconductor contact layer and absorption layer, and a second semiconductor contact layer. The semiconductor absorption layer and passivation layers are positioned between the first and second semiconductor contact layers.

Abstract: The present invention includes a planar avalanche photodiode having a first n-type semiconductor layer defining a planar contact area, and a second n-type semiconductor layer having a p-type diffusion region. Further features of the structure includes an n-type semiconductor multiplication layer, an n-type semiconductor absorption layer, and a p-type contact layer. Further embodiments include a planar avalanche photodiode having a first n-type semiconductor layer defining a planar contact area, an n-type semiconductor multiplication layer, an n-type semiconductor absorption layer and a p-type semiconductor layer electrically coupled to a p-type contact layer.

Abstract: The present invention includes a photodiode having a first p-type semiconductor layer and an n-type semi-conductor layer coupled by a second p-type semiconductor layer. The second p-type semiconductor layer has graded doping along the path of the carriers. In particular, the doping is concentration graded from a high value near the anode to a lower p concentration towards the cathode. By grading the doping in this way, an increase in absorption is achieved, improving the responsivity of the device. Although this doping increases the capacitance relative to an intrinsic semiconductor of the same thickness, the pseudo electric field that is created by the graded doping gives the electrons a very high velocity which more than compensates for this increased capacitance.

Abstract: The present invention includes an epitaxial structure (16) grown on a semi-insulating InP substrate (12). First, a buffer layer (14) is grown to isolate defects originated from substrates (12). Then an n-type layer (18) is grown to serve as n-contact layer to collect electrons. Next, a multiplication layer (20) is grown to provide avalanche gain for the APD device (10). Following that, an ultra-thin charge control layer (22) is grown with carbon doping. An absorption layer (24) is grown to serve as the region for creating electronhole pairs due to a photo-excitation. Finally, a p-type layer (28) is grown to serve as p-contact layer to collect holes.