OPTICAL POSITION DETECTING DEVICE

摘要

PURPOSE:To improve the precision of the optical position detection by forming a high impurity density region of the opposite conductivity type so as to surround the one conductivity type layer which forms a junction layer with the opposite conductivity type of the layered region, and connecting to this high impurity density region another electrode corresponding to the electrode for taking out the photocurrent, thereby reducing the non-linear errors in the photo current output. CONSTITUTION:A required positive voltage is applied to a cathode electrode 14, and the P-N junction of the photo detector surface is inversely biased by this positive voltage. When light is projected onto the photo detector surface, an electron-positive hole pair occurs in the projection point of the light, and the photocurrent due to this flows through a n<+> buried layer 5 from the cathode electrode 14, via a n<+> region 15, and from the side. And from respec tive anode electrodes 12, 13 photocurrents relatively varying according to the projection position of the light are respectively taken out. Accordingly, in the current path for the photocurrent in a semiconductor substrate 1, there is not existing any resistance component due to an n<-> epitaxial layer 3 of a high specific resistance, and in the portion of the n<+> buried layer 5, a current flows from its side via the shortest path. For this, in the photo detector surface, the occurrence of different resistance distributions depending on places is remarkably reduced.