PURPOSE: To enable the photoelectric conversion efficiency of an amorphous solar battery to be improved by a method wherein a thin film forming substrate is arranged in a magnetic field formed mainly in the parallel direction with the substrate surface so as to deposit the amorphous semiconductor thin film on the substrate using a material gas in plasma state.

CONSTITUTION: As for a thin film forming device, a parallel flat plate type plasma CVD device is used. Besides, a 5cm square transparent conductive substrate 3 is arranged on the side of an electrode 5 with a substrate heater in an i-layer forming chamber to be impressed with a magnetic field, on the other hand, in order to impress the magnetic field, a bar type samarium cobalt permanent magnet 2 is arranged in parallel with the substrate on the position 5cm distant from both sides of the substrate end so that a parallel magnetic field with the substrate surface may be formed. An i-type semiconductor thin film is formed into a hydride amorphous silicon thin film 5500 thick by cracking silane using high-frequency power at the substrate temperature of 180°C. Successively, an n type semiconductor thin film is formed into an n-type fine crystal silicon thin film 400 thick at the substrate temperature of 180°C.