PURPOSE: To improve the normal and reverse symmetricalness of voltage-current characteristics by a method wherein two Schottky diodes made of the same amorphous silicon films and metallic films formed into the same type by patterning process are connected in series.

CONSTITUTION: N type or P type amorphous silicon films 23 and i-type amor phous silicon films 24 are successively laminated on two lower electrodes 21, 22 formed at the adjoining positions on a glass substrate 20. Next the films 24 are formed into island type parts by etching process to be left only on the lower electrodes 21, 22. Besides, silicon nitride or silicon dioxide insulating films are formed into passivation films 25 and then a contact hole for leading out Schottky electrodes is opened. Finally metallic films 26 for Schottky junction are evaporated on the contact hole simultaneously connecting the two diodes with each other utilizing the metallic films 26 as upper electrodes Through these procedures, the threshold value may be increased to improve the normal and reverse symmetricalness of voltage-current characteristics.