Fabrication of single or multiple gate field plates

A high electron mobility transistor (HEMT), comprising:

• a nucleation layer;
• a channel layer on the nucleation layer;
• a barrier layer on the channel layer;
• a spacer layer on the barrier layer;
• and
• source and drain electrodes making ohmic contacts through the barrier layer such that an electric current flows between the source and drain electrodes when a gate electrode is biased at an appropriate level;
• wherein the spacer layer is etched to expose the barrier layer and the gate electrode is deposited such that at least a bottom portion of the gate electrode is on a surface of barrier layer,
• wherein a top portion of the gate electrode is patterned to extend across the spacer layer so that the top portion of the gate electrode forms a field plate extending a distance away from the gate electrode towards the drain electrode;
• and
• wherein a passivation layer covers both the gate electrode and at least a portion of the spacer layer.