A normally-off heterojunction field-effect transistor is provided, including a superposition of a first layer, of III-N type, and of a second layer, of III-N type, so as to form a two-dimensional electron gas; a stack of an n-doped third layer making electrical contact with the second layer, and of a p-doped fourth layer placed in contact with and on the third layer, a first conductive electrode and a second conductive electrode making electrical contact with the two-dimensional electron gas; a dielectric layer disposed against a lateral face of the fourth layer; and a control electrode separated from the lateral face of the fourth layer by the dielectric layer.