Electronic device and a method for making the same

A method for making an electronic device which comprises a substrate, a gate electrode formed on one surface of said substrate, and a gate insulating film covering said substrate and said gate electrode therewith, characterized in that where a semiconductor active layer having a width smaller than said gate electrode is formed just above said gate electrode, said gate insulating film and said semiconductor active layer are continuously formed by a Plasma CVD method in such a way that said semiconductor active layer is etched as being narrower in width than said gate electrode, and a source electrode and a drain electrode both made of a conductor layer is formed through an ohmic contact layer on said semiconductor active layer, that where said ohmic contact layer is formed between said semiconductor active layer and said source electrode and also between said semiconductor active layer and said drain layer, respectively, the ohmic contact layers, said source electrode and said drain layer are continuously formed by a sputtering method, that where a space between said source electrode and said drain electrode spaced from each other is wider than a space between said ohmic contact layers kept away from each other, said source electrode, said drain electrode and said ohmic contact layers are all continuously removed with an etchant, and that a light irradiating means is provided at the other surface of the substrate, where the gate electrode has not been formed, so that light is permitted to pass vertically to the substrate.