A transistor comprising an active region, with source and drain electrodes formed in contact with the active region and a gate formed between the source and drain electrodes and in contact with the active region. A first spacer layer is on at least part of the surface of the active region between the gate and the drain electrode and between the gate and the source electrode. The gate comprises a generally t-shaped top portion that extends toward the source and drain electrodes. A field plate is on the spacer layer and under the overhang of at least one section of the gate top portion. The field plate is at least partially covered by a second spacer layer, with the second spacer layer on at least part of the surface of the first active layer and between the gate and the drain and between the gate and the source. At least one conductive path electrically connects the field plate to the source electrode or the gate.