Gated-anode diodes for RF and microwave rectifiers for WPT applications: a simulation study on DC and RF characteristics

AlGaN/GaN HEMT-based gated-anode diode (GAD) has been investigated with a physics-based TCAD simulation tool to understand its electrical transport characteristics. The simulation study predicted that the GAD exhibited low turn-on voltage ( \(V_{\text {on}}\) $V_{\text{on}}$ = + 0.77 V) over a conventional Schottky barrier diode (SBD). However, the GAD suffers from low breakdown voltage ( \(V_{\text {BD}}\) $V_{\text{BD}}$ ) because of strong electric field crowding at the gate edge. On the other hand, a δ-doped GaN cap (δ-DGC) layer has been able to spread out the electric field along the channel. With such modification in the epi-structure, a \(V_{\text {BD}}\) $V_{\text{BD}}$ of ~ 335 V could be achieved with the gated-anode-to-cathode distance ( \(L_{\text {gac}}\) $L_{\text{gac}}$ ) of 10 μm. TCAD-based RF simulation and small-signal S-parameter analysis were carried out to evaluate the expected RF performance of the GADs. From the transient response of the extracted small-signal equivalent circuit parameters, the cut-off frequency ( \(f_{\text {c}}\) $f_{\text{c}}$ ) of the GADs with δ-DGC layer was 35.6 GHz at the exact turn-on condition ( \(V_{\text {on}}\) $V_{\text{on}}$ ) of the device.