An HEMT includes: a heterostructure; a dielectric layer on the heterostructure; a gate electrode, which extends throughout the thickness of the dielectric layer; a source electrode; and a drain electrode. The dielectric layer extends between the gate electrode and the drain electrode and is absent between the gate electrode and the source electrode. In this way, the distance between the gate electrode and the source electrode can be designed in the absence of constraints due to a field plate that extends towards the source electrode.