Optical properties of photoconductor using crystalline selenium

Recently, there has been an increased need for highly sensitive solid-state imaging devices to develop high-resolution and high-speed image sensors. Crystalline selenium is a suitable material for a photosensitive layer because of its high absorption coefficient in the visible light region. In our experiment with an image pick-up tube using crystalline selenium as a photosensitive layer, a high-resolution image was obtained for the first time. In addition, test sandwich cells have been fabricated to demonstrate a large photocurrent multiplication phenomenon with very high quantum efficiency greatly exceeding unity as a result of injection carriers from an external electrode caused by a high electric field at the interface between the crystalline selenium and the metal electrode. (author)