In-depth caracterisation of the structural phase change of Germanium Telluride for RF switches

This paper presents the phase change characterization of Germanium Telluride (GeTe) used for RF switches when a direct heating is performed. The study describes the method to activate the transition between crystalline and amorphous states, allowing to reach a resistance ratio of 1.8.10
⁴
between both states. RF measurements were performed up to 40 GHz on fabricated switches, showing an ON-state resistance of 1.7 Ω. An OFF-state capacitance of 5.4 fF was extracted from simulation, resulting in an estimated cutoff frequency of 17 THz, which is at the state-of-the-art. The study also shows the importance of the GeTe thickness to optimize the performance of the device.