| 摘要 |
PURPOSE:To improve structural strain at an interface between neighboring amorphous semiconductors and to improve the film quantity of an amorphous SiGe layer, by increasing the width of an optical forbidden band as the I-type amorphous SiGe layer of a photoelectromotive force element approaches the light inputting side. CONSTITUTION:Light is inputted in an amorphous element through a light transmitting insulating substrate 1 and a transparent conducting film 2. Generated electrons and holes are collected in an electrode film 12 and the transparent conducting film 2. P type layers 3, 6 and 9 are composed of amorphous silicon carbide. Of I-type layers, the I-type layers 4 and 7, which are close to the light inputting surface, are composed of amorphous silicon. An I-type layer 10, which is the farthest, is composed of amorphous SiGe. N type layers 5, 8 and 11 are composed of amorphous silicon, in which phosphorus is doped. The ratio of Ge to Si in the I-type layer 10 is made gradually large, from the side of the neighboring P type layer 9 toward the side of the N type layer 11. The width of the optical forbidden and (b) of the I-type layer 10 is made gradually large as the side of the P type layer, i.e., the incident surface of the light is being approached. Thus the difference in energy levels of a valence band (c) and a conduction band (a) in the vicinity of the boundary with the P type layer 9 is alleviated and the output characteristics of the photoelectromotive force element can be improved to a large extent. |
