| 摘要 |
PURPOSE:To obtain a photosensor, whose output level is large, by providing an epitaxial layer having low impurity concentration on the surface of a semiconductor substrate, and forming a P-N junction having low impurity concentration. CONSTITUTION:On a P-type Si substrate 1, an N<--> type first epitaxial layer 2 is grown. An N<-> type second epitaxial layer 3 is further grown on the layer 2. Then, the layer 2 and the layer 3 are isolated by a P<+> type isolating region 4, and an island region 5, which is surrounded by the substrate 1 and the region 4, is formed. A P-N junction formed by the layer 3 and the substrate 1 is used as a photosensor. As the photosensor in this constitution, the junction, which is closed to a PIN structure having low impurity concentration, is obtained between the layer 2 and the substrate 1. Therefore, a depletion layer can be expanded readily, and the detected output level of the photosensor can be made high. |
