Group III nitride-based radio frequency transistor amplifiers having source, gate and/or drain conductive vias

A radio frequency (“RF”) transistor amplifier, comprising:

• an interconnection structure having at least first and second conductive structures on an upper surface thereof;
• and
• a Group III nitride-based RF transistor amplifier die mounted on the upper surface of the interconnection structure, the Group III nitride-based RF transistor amplifier die including a semiconductor layer structure, at least one conductive source via that is connected to a source region of the Group III nitride-based RF transistor amplifier die, the at least one conductive source via extending through the semiconductor layer structure, and an additional conductive via that extends through the semiconductor layer structure,
• wherein a first end of the additional conductive via is connected to the first conductive structure through a contact that is interposed between the interconnection structure and the Group III nitride-based RF transistor amplifier die,
• wherein the additional conductive via is at least one of a conductive gate via and a conductive drain via.