Light-emitter and transistor

A transistor comprising:

• a bank defining an aperture having a major axis and a minor axis in plan view;
• a gate electrode located below or above the aperture;
• a gate insulation film located closer to the aperture than the gate electrode is;
• a base layer located below the bank and having a source electrode and a drain electrode, at least a portion of the source electrode and a portion of the drain electrode being located within the aperture;
• and
• a semiconductor layer located within the aperture and in contact with the base layer, the semiconductor layer corresponding in position to the gate electrode with the gate insulation film interposed therebetween wherein
• in a cross-section passing through the major axis of the aperture in a perpendicular direction to the top surface of the base layer,
• the bank has an upper surface located at a height of h0 with reference to the top surface of the base layer, and a circumferential surface facing the aperture,
• when h denotes a height of a given point on the circumferential surface with reference to the top surface of the base layer, and x denotes a distance, measured in a direction along the top surface, of the given point from a boundary between the upper surface and the circumferential surface of the bank, a second-order derivative of h with respect to x is continuous at a point corresponding to the boundary, h being smaller than h0,
• an inflection point of the second-order derivative, at which the second-order derivative changes from approximately 0 to a negative value, is located at a height of 0.9h0 or greater with reference to the top surface of the base layer, and
• a top surface of the functional layer is in contact with the circumferential surface at a contact point near the inflection point.