High Performance mm Wave AlN/GaN MISHEMTs on 200 mm Si Substrate

Abstract

We report high performance AlN/GaN MISHEMTs grown using MOCVD on 200 mm Si substrates with in-situ silicon nitride (Si3N4) as the common gate insulator and access region passivation layer. The RF small and large-signal performance trade-offs of AIN and Si3N4 thickness scaling are systematically examined. Ultra-thin barrier and dielectric stacks (AIN < 2.5 nm, Si3N4 ≤ 2 nm) lead to excellent small-signal performance with peak fmax: ~190 GHz at 110 nm gate lengths but trapping induced current collapse is worsened, degrading the RF large-signal performance. For thicker stacks (AIN ≥ 2.5 nm and Si3N4 ≥ 3 nm), current collapse is lower and large-signal performance improves significantly while still maintaining. fmax>150 GHz with good linearity. Record large-signal performance (@ 28 GHz) at 200 μm gate width is demonstrated with a PSAT: 2.2 W/mm (26.8 dBm) and PAE : 55.5% at Vd: 10 V and a PSAT: 2.8 W/mm (27.5 dBm) and PAE : 54.8% at Vd: 20 V.