Patent ID: 8441619

Claim:
A photodetector comprising: a semiconductor substrate; a photoelectric converting portion formed in said semiconductor substrate to generate electric charges corresponding to a received light amount; a charge separating portion having a separation electrode formed on a general surface of said semiconductor substrate; a charge accumulating portion having an accumulation electrode formed on the general surface of said semiconductor substrate; a barrier electrode formed on the general surface of said semiconductor substrate between said separation electrode and said accumulation electrode; a barrier-height adjusting portion electrically connected to said barrier electrode; and a charge discarding portion; wherein said charge separating portion is configured to separate undesired electric charges from the electric charges generated by said photoelectric converting portion by use of a potential barrier, which is formed in said semiconductor substrate under said barrier electrode by applying a voltage to said barrier electrode, said barrier-height adjusting portion determines the voltage applied to said barrier electrode according to an electric charge amount supplied from said photoelectric converting portion to adjust a height of said potential barrier, the electric charge amount supplied from said photoelectric converting portion based upon an amount of light received; said charge accumulating portion is configured to accumulate effective electric charges that are electric charges flowing from said charge separating portion into said charge accumulating portion over said potential barrier, said charge discarding portion is configured to discard the undesired electric charges separated by said charge separating portion, and the effective electric charges accumulated in said charge accumulating portion are provided as an output of the photodetector, wherein said barrier electrode is formed on said semiconductor substrate through an insulating layer, said photoelectric converting portion, said charge separating portion, said barrier electrode and said charge accumulating portion are aligned in a row, and said barrier-height adjusting portion and said charge discarding portion are provided at one side of said row such that said barrier-height adjusting portion is positioned adjacent to said charge separating portion, and said charge discarding portion is positioned adjacent to said photoelectric converting portion.