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 Hf
0.5
Zr
0.5
O
2
(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.