Ultraviolet light-receiving element

In the ultraviolet light receiving element using Group III nitride semiconductor, providing ultraviolet light receiving element having high light-receiving sensitivity. By irradiating light having higher energy than the band gap energy of the undoped layer 44, by a layer depleted, electrons are excited to the conduction band 61 from the valence band, electrons - hole pairs are generated. Its generated electrons - band structure is changed by hole pairs, thereby also lower portion of energy from the quasi-Fermi level 62 interface of the electron undoped layer 43 and the undoped layer 44, two-dimensional electron gas 63 There is formed. Since the two-dimensional electron gas 63 acts as a channel, a large current flows by applying a voltage between the drain electrode 46-the source electrode 7.