A device includes a semiconductor die, a source contact, a drain contact, a first passivation layer, a T-shaped gate contact, a field plate, and a second passivation layer. The semiconductor die generally includes a plurality of semiconductor layers disposed on an insulating substrate. The source contact and the drain contact are electrically coupled to a channel formed in the semiconductor layers and defining an active area of the device. The first passivation layer generally covers the active area of the device, the source contact, and the drain contact. The T-shaped gate contact may be disposed within the active area of the device. The T-shaped gate contact is generally electrically separated from the channel and comprises a column portion and a cap portion. The field plate may be disposed above the active area of the device. The field plate is generally adjacent to and laterally separated from the cap portion of the T-shaped gate contact. The second passivation layer generally covers the first passivation layer, the cap portion of the T-shaped gate contact, and the field plate.