A WR-5 (140-220 GHz) Quasi-Optical Phase Shifter Array Based on GaAs Schottky Diodes Integrated on Thin Silicon Membranes

This work reports on a proof-of-concept phase shifter quasi-optical diode array operating in the WR-5 frequency band (140 GHz – 220 GHz). The array incorporates GaAs quasi-vertical Schottky diodes heterogeneously integrated onto a $15 \mu\mathrm{m}$ silicon membrane. The design utilizes varactor Schottky diodes with low device parasitics at millimeter-wave frequencies, a thin host substrate which suppresses substrate modes, and silicon as an integration platform which offers superior thermal management properties compared to GaAs. A series resistance of $11\ \Omega$ was extracted for the 36-element array based on current-voltage DC measurements. 1-port error-corrected scattering parameter data was obtained for the array using a quasi-optical measurement setup, and a maximum phase shift of 30° was measured at 158 GHz.