Photodiode array structure for cross talk suppression

An avalanche photodiode array comprising:

• a plurality of avalanche photodiodes, each avalanche photodiode including a stack of active photodiode materials comprising:
• a first electrical contact layer comprising indium phosphide;
• a second electrical contact layer;
• an absorber material layer and an avalanche material layer each disposed between the first electrical contact layer and the second electrical contact layer, wherein the avalanche material layer comprises indium phosphide, and the absorber material layer comprises InGaAsP, and
• an optical interface surface to the avalanche photodiode, the optical interface surface consisting of an exposed surface of the first electrical contact layer, arranged for incident external radiation to directly enter the first electrical contact layer;
• wherein each avalanche photodiode stack of active photodiode materials is laterally isolated from the other avalanche photodiodes in the photodiode array;
• and
• a cross talk blocking region disposed laterally adjacent to each avalanche photodiode in the array, between laterally isolated stacks of active photodiode material, maintaining an exposed surface of the first electrical contact layer of each avalanche photodiode in the array, the cross talk blocking region comprising GaInAs.

A method for manufacturing an array of avalanche photodiodes comprising:

• forming on a substrate a layer of cross talk blocking material that blocks transmission of photons through the cross talk blocking material;
• forming a stack of active photodiode layers on the cross talk blocking material layer, the stack of active photodiode layers including a first electrical contact layer, an absorber layer, an avalanche layer, and a second electrical contact layer;
• removing regions of the stack of active photodiode layers through a full thickness of the layers, at sites across the substrate, to form an array of laterally isolated avalanche photodiodes, each avalanche photodiode being isolated laterally from the other avalanche photodiodes in the array by the removal of regions of the stack of active photodiode layers;
• electrically connecting one of the electrical contact layers of each avalanche photodiode in the array to an individual contact pad of a microelectronic chip;
• completely removing the substrate on which the stack of active photodiode layers was formed, producing an array of laterally isolated avalanche photodiodes devoid of a substrate;
• and
• removing regions of the cross talk blocking material layer at each avalanche photodiode to expose an optical interface surface at each avalanche photodiode in the array.

A method for manufacturing an array of avalanche photodiodes comprising:

• forming a stack of active photodiode layers on a substrate, the stack of active photodiode layers including a first electrical contact layer, an absorber layer, an avalanche layer, and a second electrical contact layer;
• forming on the stack of active photodiode layers a layer of cross talk blocking material that blocks transmission of photons through the cross talk blocking material;
• removing the cross talk blocking material layer at a plurality of sites on the stack of active photodiode layers to expose avalanche photodiode optical interface surface sites for an array of avalanche photodiodes;
• bonding the cross talk blocking material layer to a microlens array aligned with the plurality of optical interface surface sites;
• completely removing the substrate on which the stack of active photodiode layers was formed, producing an array of avalanche photodiode sites devoid of a substrate;
• and
• removing regions of the stack of active photodiode layers through a full thickness of the layers, at the optical interface surface sites across the substrate, to form an array of laterally isolated avalanche photodiodes, each avalanche photodiode being isolated laterally from the other avalanche photodiodes in the array by the removal of regions of the stack of active photodiode layers.