SPAD-based photodetectors

A semiconductor avalanche photodiode for light detection, the avalanche photodiode comprising:

• a p-n junction comprising a first shallow extrinsic semiconductor layer with a first type of doping embedded in a second well-shaped extrinsic semiconductor layer with a second type of doping opposite to the first type of doping;
• a first electric contact configured to electrically connect the first semiconductor layer;
• a second electric contact configured to electrically connect the second semiconductor layer;
• an avalanche region at the interface between the two semiconductor layers configured to undergo avalanche breakdown when triggered by the light to be detected;
• and
• a dielectric isolation trench extending into the second well-shaped semiconductor layer and surrounding an outer periphery of the avalanche region to prevent premature edge breakdown in the avalanche photodiode;
• wherein the isolation trench is arranged, in a radial direction, in-between the first electric contact and the second electric contact;
• wherein:
• the isolation trench comprises an encasement made of a dielectric material and a metallic core surrounded by the dielectric encasement;
• and
• the thickness of the isolation trench is greater than or equal to 90% of the thickness of the second well-shaped semiconductor layer, the isolation trench thus forming a deep trench isolation within the second well-shaped semiconductor layer.