US Patent 8987651 Photodetector including photodiodes overlapped with each other

An object is to reduce the size and manufacturing cost of a photodetector. In order to reduce the area where a visible light sensor and an infrared light sensor are provided, a first photodiode that detects visible light and a second photodiode that detects infrared light are arranged to overlap with each other so that visible light is absorbed first by the first photodiode, whereby significantly little visible light enters the second photodiode. Further, the first photodiode overlapping with the second photodiode is used as an optical filter for the second photodiode. Therefore, a semiconductor layer included in the first photodiode absorbs visible light and transmits infrared light, and a semiconductor layer included in the second photodiode absorbs infrared light.