High-electron-mobility transistors that include field plates are described. In a first implementation, a HEMT includes a first and a second semiconductor material disposed to form a heterojunction at which a two-dimensional electron gas arises and source, a drain, and gate electrodes. The gate electrode is disposed to regulate conduction in the heterojunction between the source electrode and the drain electrode. The gate has a drain-side edge. A gate-connected field plate is disposed above a drain-side edge of the gate electrode and extends laterally toward the drain. A second field plate is disposed above a drain-side edge of the gate-connected field plate and extends laterally toward the drain.