UV illumination effects on AlGaN/GaN HEMTs for tunable RF oscillators

We present the first investigation of AlGaN/GaN HEMTs as optically-controlled microwave semiconductor devices for use in next-generation, high-power microwave photonics systems. Measurements show a modest change in S21 in the presence of UV illumination that induces internal photoconductive and photovoltaic effects. This contrasts with the significant shift in the measured gate capacitance, which can be used to tune future oscillators. This is investigated through the design of a 2.4 GHz Pierce oscillator with an optical tuning range of 3 MHz.