Abstract
The present invention provides a photodiode to increase the blue light response, which comprises a semiconductor substrate of the first conductive type, a semiconductor region of the first conductive type formed on the semiconductor substrate of the first conductive type, a semiconductor region of the second conductive type formed on the semiconductor region of the first conductive type, a depletion region formed by the adjacent regions of the semiconductor region of the first conductive type and a semiconductor region of the second conductive type together, and a semiconductor layer of the first conductive type formed at the outer periphery of semiconductor region of the first conductive type. The semiconductor region of the second conductive type and the depletion region can absorb the energy of the incident light, and separate most of the electron-holes in the depletion region, and conduct the current to form voltage oscillation by the semiconductor layer of the first conductive type.