SPAD-based photodetectors
An integrated photodetecting optoelectronic semiconductor component configured to deliver an output signal indicative of the intensity of light irradiating the component. The component may include a SPAD-based main detection device configured to detect incoming photons and to deliver an output signal based on the detected photons. The component may also include a SPAD-based reference detection device proximate to the main detection device where the reference detection device has the same electro-optical behaviour as the main detection device, is configured to detect incoming photons, configured to deliver a reference signal based on the detected photons, and has a light inlet for incoming photons. The component may also include a neutral density filtering device and a controller configured to determine a nominal output signal, compare the nominal output signal with the output signal delivered by the main detection device, and adjust an operating parameter based on the comparison.
1. 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.
2. The photodiode of claim 1 , wherein the photodiode is of the Silicon On Insulator type.
3. The photodiode of claim 1 , wherein the isolation trench is in direct lateral contact with the outer boundary of the first shallow semiconductor layer.
4. The photodiode of claim 1 , wherein the photodiode lacks any edge breakdown preventing semiconductor guard ring.
5. The photodiode of claim 1 , wherein the metallic core comprises at least one plate-shaped metallic element.
6. The photodiode of claim 5 , wherein the main longitudinal axis of the at least one plate-shaped metallic element extends along a main direction of light entry into the photodiode.
7. The photodiode of claim 5 , wherein the metallic core comprises at least two plate-shaped metallic elements, and wherein the plate-shaped metallic elements are arranged concentrically within the dielectric encasement.
8. The photodiode of claim 5 , wherein the metallic core comprises at least two plate-shaped metallic elements, and wherein each plate-shaped metallic element is spaced apart from its neighbouring plate-shaped metallic elements.