PURPOSE: To increase a current value when a light is emitted to a photoconductive film by treating with hydrogen plasma a substrate before accumulating an a-Si film.

CONSTITUTION: Before SiH4 gas is fed to a chamber, hydrogen is fed through a gas guide pipe 4, an RF power source 8 is connected with an electrode 2 to apply an RF power to generate a plasma discharge between electrodes 2 and 3. A substrate 5 is exposed in hydrogen plasma discharge atmosphere during the period. After this process is finished, the SiH4 gas is fed to accumulate an a-Si. The reason why a photocurrent value is increased is presumed because hydrogen atoms or metal atoms which form a discharge electrode are strongly bonded in a single unit or in the form of oxide to the substrate to be contributed to the increase in the conductivity of the a-Si film. The treating conditions preferably include 100sec or higher of flow rate, 10min or longer of time, and 50W150W of RF power.