| 摘要 |
PURPOSE:To accelerate the falling speed of optical response regardless of the lower intensity of illumination by a method wherein in an optical senser using the optoelectric conduction effect of an amorphous thin film containing hydrogen and other additives, the composition ratio of hydrogen or other additives contained in the thin film is varied in the film thickness direction. CONSTITUTION:The forbidden band width in an element is fluctuated in the film thickness direction by means of fluctuating the composition ratio of hydrogen or other additive in the hydrogenated silicon thin film to form a region with narrow forbidden width into layer. 0.2 Torr of silane gas is led into a plasma CVD device to decompose silane by high frequency discharge so that hydrogenated amorphous silicon may be deposited on a glass substrate. 10-30% of hydrogen is to be contained in the deposited amorphous silicon. The composition ratio of such a hydrogen depend on the silane gas pressure, high frequency power and substrate temperature. The thin film with the forbidden band distributed in the film thickness direction can be formed by fluctuating the temperature of substrate during the process of growing the thin film by depositing amorphous silicon.
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