High Power AlGaN/InGaN/AlGaN/GaN Recessed Gate Heterostructure Field Effect Transistor with InGaN as the RIE Etching Stop Layer

Sensor Electronic Technology, Inc. proposes a radically different approach for pushing the GaN HEMT performance above the 200 GHz range. In this approach, called Drain Gate Recess, the shape of the recessed gate is such that the gate metal is CLOSER to the channel near the drain edge of the channel. The result is a variation of the device threshold voltage along the channel that makes the electric field along the channel much more uniform and might roughly double the average electron velocity in the channel. The conventional approach for improving the performance of GaN HEMTs involves field plates that work by introducing a metal gate extension over a dielectric. The gate extension splits the high field region under the gate (typically at the drain side of the gate) between two high field regions rather than one, reducing the maximum field. This results in (a) increase in the breakdown voltage and (b) improved device reliability. Although the field plate approach reduces the maximum electric field under the gate, the additional capacitance and corresponding velocity profile limit high frequency operation for these devices. We propose a radically different approach for pushing the GaN HEMT performance above the 200 GHz range.