A GaAsP-base light emitting element capable of sustaining an excellent light emission property for a long period, and a method for manufacturing thereof are provided. As a result, even if a body to be detected such as a finger contacts the extension area, it is possible to reduce the amount of the change of an electrostatic capacitance with respect to the movement of the body to be detected. Then, a gate trench having a barrier layer is formed in the interfacial dielectric layer.