Field-effect transistor (FET) having oxide insulating layer disposed on gate insulating film and between source and drain electrodes, and display element, display and system including said FET, and method of manufacturing said FET

A method of manufacturing a field-effect transistor, comprising:

• forming a first insulating layer as gate insulating film on a gate electrode and a substrate,
• forming a semiconductor layer on the first insulating layer, with the first insulating layer interposed between the semiconductor layer and the gate electrode;
• forming a second insulating layer covering at least a part of a surface of the semiconductor layer, the second insulating layer including an oxide including silicon and an alkaline earth metal;
• covering the semiconductor layer and the second insulating layer to form an electroconductive layer;
• and
• etching the electroconductive layer while using the second insulating layer as an etching stopper to form a source electrode and a drain electrode, adjacent to the semiconductor layer,
• wherein molar percent of alkaline earth oxides in the second insulating layer is smaller than molar percent of silicon oxides in the second insulating layer.