be not less than 10 w cm 2 and preferably not less than 100 w cm 2 the irradiation time per pulse is generally not more than 1 10 seconds this pulsed light is either visible light or ultraviolet light and should have a wavelength not longer than 700 nm the amorphous semiconductor obtained by the above described method of the invention has an improved light resistance the term amorphous silicon semiconductor as used in this specification means any and all amorphous semiconductors containing si as an essential component and includes a si and alloys of a si with microcrystalline si sn ge and or other elements typical of such amorphous semiconductors are the amorphous semiconductor according to the present invention can be advantageously used in the fabrication of solar cells and other semiconductor devices of the pin construction a schottky construction or the like in the case of a pin type solar cell it is known that the use of a si 1 x c x for the p layer on the light incident side results in higher efficiency and voltage u s pat no 4 388 482 the following examples are intended to illustrate the present invention in further detail and should by no means be construed as limiting the scope of the invention under the conditions set forth in table 1 pure monosilane gas sih 4 was subjected to glow discharge decomposition to give an intrinsic amorphous silicon film on a corning glass 7059 substrate the films were designated as examples 1 through 4 respectively each of the semiconductor films according to examples 1 through 4 was left standing in a vacuum of about 10 3 torr at 160 u00b0 c in a cryostat and irradiated with xenon pulsed light at 20 minute intervals the intensity of.