Surface-charge controlled AlGaN/GaN-power HFET without current collapse and gm dispersion

We demonstrate high voltage HFET operation with suppression of gm dispersion and current collapse using an n-type thin GaN cap layer combined with SiN passivation and a recessed ohmic structure. Polarization-induced surface charge was controlled. Off state and on-state breakdown voltages were 140 V and 70 V. We obtained power HFETs with high CW operation voltage of 35 V without any heat sinking method.