Impact of a Moderately Doped Contact Layer on Breakdown Voltage in AlGaN/GaN Gated-Anode Diodes for Microwave Rectification

We fabricated a gated-anode diode employing an AlGaN/GaN high electron mobility transistor (HEMT) to serve as a rectification device in a 5.8-GHz band microwave wireless power transmission (WPT) system. To enhance the breakdown voltage and enable the devices to handle high power, a moderately doped contact layer was proposed and its impact on device performance was comprehensively investigated. We confirmed that medium doping facilitated depletion, achieving high breakdown voltage even with a short gate-to-contact spacing. However, an increase in contact resistance and a consequent decrease in forward current were observed as adverse effects. By optimizing the doping concentration, we successfully enhanced the breakdown voltage while suppressing the current drop, achieving a high-power density of 7.0 W/mm.