Performance Improvement of GaN HEMT with Ferroelectric Gate Stacks for RF/mm-Wave Switching Applications

Gallium Nitride (GaN) based high-electron-mobility transistors (HEMTs) are leading candidates for high- performance RF amplifiers, particularly for wireless communication applications. RF switching and routing is another key application in wireless systems. In this work, GaN HEMTs integrated with Hf0.5Zr0.5O2 (HZO) ferroelectric (FE) gate stacks are used to improve the performance of RF switches at mm- wave frequencies. FeHEMTs with high switch figure of merit (FOM), low insertion loss of 1.4 dB and high isolation > 19.4 dB at 30 GHz have been fabricated and characterized. Study of the bias- and frequency-dependent response of metal-ferroelectric-metal (MFM) capacitors, in conjunction with modeling based on the Landau-Khalatnikov formalism, are used to understand the experimental results. This study shows that the observed reduction in RF capacitance arises from dispersion in the HZO film. This provides a simple approach to achieve high performance in RF/millimeter-wave switching applications.