Patent ID: 7601992
Filing Date: 2009-10-13
Classification: G01S,H01L,H04N

Abstract:
1. A light detecting element formed in a semiconductor device, the light detecting element comprising: a photosensitive unit for receiving light irradiated from a light source, said photosensitive unit generating electrons and holes, each of which the number varies with quantity of light received at the photosensitive unit; a carrier separation unit with a separation control electrode, said carrier separation unit separating the electrons and holes generated at said photosensitive unit into object carriers and non-object carriers according to control of electric potential applied to the separation control electrode, said object carriers being one of the electrons and holes, said non-object carriers being another of the electrons and holes; a recombination unit with a recombination control electrode, said recombination unit stimulating recombination between the object carriers generated at said photosensitive unit in a light period and the non-object carriers generated at said photosensitive unit in an extinction period according to control of electric potential applied to the recombination control electrode, said light period being a period of time that said light source is operated, said extinction period being a period of time that said source is extinguished; an output unit for picking out the object carriers which remain after the recombination at said recombination unit; an object carrier holding unit for gathering the object carriers generated at said photosensitive unit to hold the object carriers until the recombination; a non-object carrier holding unit for gathering the non-object carriers generated at said photosensitive unit to hold the non-object carriers until the recombination, wherein said recombination unit stimulates the recombination between the object carriers held at said object carrier holding unit and the non-object carriers held at said non-object carrier holding unit; an element formation layer of a first conductive type, said element formation layer being formed on a main surface of a semiconductor substrate; a well region of a second conductive type, said well region being formed at a main surface side within said element formation layer; a surface electrode which is formed on the main surface of said element formation layer to face at least said well region though an insulating layer, said surface electrode having translucency; a first holding region of the second conductive type, said first holding region being formed within said well region and at the main surface side of said element formation layer as said object carrier holding unit; a second holding region of the first conductive type; said second holding region being formed within said first holding region and at the main surface side of said element formation layer as said non-object carrier holding unit; and a common control electrode as said separation control electrode and said recombination control electrode, said common control electrode being located to face said second holding region through said insulating layer, said common control electrode having translucency, wherein said photosensitive unit includes said element formation layer which generates the electrons and holes, and wherein said recombination unit includes at least one of said first holding region and said second holding region.