High Performance and Highly Robust AlN/GaN HEMTs for Millimeter-Wave Operation

We report on a 3 nm AlN/GaN HEMT technology for millimeter-wave applications. Electrical characteristics for a 110 nm gate length show a maximum drain current density of 1.2 A/mm, an excellent electron confinement with a low leakage current below 10 μA/mm, a high breakdown voltage and a FT/Fmax of 63/300 GHz at a drain voltage of 20V. Despite residual trapping effects, state of the art large signal characteristics at 40 GHz and 94 GHz are achieved. For instance, an outstanding power added efficiency of 65% has been reached at VDS = 10V in pulsed mode at 40 GHz. Also, an output power density of 8.3 W/mm at VDS = 40V is obtained associated to a power added efficiency of 50%. At 94 GHz, a record CW output power density for Ga-polar GaN transistors has been reached with 4 W/mm. Additionally, room temperature preliminary robustness assessment at 40 GHz has been performed at VDS = 20V. 24 hours RF monitoring showed no degradation during and after the test.