Characterization of Phase Change Material Germanium Telluride for RF Switches

This paper presents the simulation and measured results of a phase-change material (PCM) based radio-frequency (RF) switch optimized to improve the ratio between OFF-state and ON-state resistivity. Various samples having germanium telluride (GeTe) films are developed and imaged using Atomic Force Microscope (AFM) and are compared with cross-wafer resistance measurement results to determine the optimum sputtering conditions of the GeTe films. A simple four-layer fabrication process for GeTe based switches is presented. Several switches with different micro-heater dimensions are compared to investigate the performance of heater and its impact on the isolation performance of switch. A compact RF series switch has been measured, demonstrating an insertion loss of only 0.29 dB and an OFF-state isolation better than 23dB over DC-26 GHz frequency range, yielding a relatively high Roff/Ron ratio.