Substrate RF Losses and Non-linearities in GaN-on-Si HEMT Technology

The analysis and mitigation of substrate-related RF losses and non-linearities is crucial to enable GaN HEMTs on silicon for front-end transceivers for 5G and beyond. Here, for the first time, the impact of material growth and HEMT fabrication process on the substrate RF losses and linearity is studied using the effective substrate resistivity, ρ eff , and 2nd harmonic power, H2, figures-of-merit. It is shown that CPWs on fully-processed, GaN-on-high resistivity (3-6 kΩ•cm), 200 mm CZ-Si wafers can achieve H2 levels ~ -85 dBm (at P out ~15 dBm) with ρ eff ~1 kΩ•cm.