Experimental Investigation of Thermal Actuation Crosstalk in Phase-Change RF Switches Using Transient Thermoreflectance Imaging

This article reports an experimental investigation of transient heat distribution and thermal actuation crosstalk in phase-change material (PCM) germanium telluride (GeTe)-based radio frequency (RF) switches. The RF switches are designed and optimized for efficient thermal energy transport from the embedded microheater to the PCM. Various multiport miniaturized monolithically integrated complex RF components require several switches to be integrated extremely close to each other. Thermal crosstalk is crucial in multiport complex devices to ensure that individual tuning elements actuate independently without influencing nearby switches' performance. Thermal cross section simulations are performed using multiphysics finite-element modeling (FEM) to optimize the heat distribution within the PCM channel and are experimentally validated via transient thermoreflectance imaging technique with ultrafast temporal and spatial resolution. The devices are fabricated in-house using a custom eight-layer microfabrication process. The optimum device bias conditions, melt-quench sequence, and thermal actuation crosstalk limits are experimentally validated to develop miniaturized monolithic densely packed complex reconfigurable phase-change circuits. It is the first-ever demonstration of experimental transient thermal insights on phase-change RF switches.