Integrated circuit FET photodetector - has polycrystalline silicon transparent gate electrode on silicon oxide layer for positive charge on boundary surface

摘要

The photodetector which can be a depletion mode field effect transistor in integrated circuit form, with a silicon base, has a transparent gate electrode. This can be of polycrystalline silicon, and positioned on a thin Si02 layer through which the radiation can also pass to excite electrons in the boundary surface between this layer and silicon layer below. This results in a more positive charge on the boundary. The source and drain electrodes are each side of this strongly doped layer. This is achieved by ion implantation of a foreign substance followed by heat treatment to obtain the required electrical and optical properties. Caesium ions can be used for implantation. The channels in the transistor structure can be formed by a p-type doped zone in an n-type silicon substrate. The device can be used in an X-Y addressing system.