An enhancement-mode high-electron-mobility transistor comprises a structure including a stack made of III-V semiconductor materials defining an interface and capable of forming a conduction layer in the form of a two-dimensional electron gas layer; a source electrode and a drain electrode forming an electrical contact with the conduction layer; and a gate electrode arranged on top of the structure, between the source electrode and the drain electrode. The structure comprises a bar that is arranged below the gate electrode and passes through the interface of the stack. The bar comprises two semiconductor portions exhibiting opposite types of doping, defining a p-n junction in proximity to the interface.