Germanium Telluride (GeTe) can be described as a non-volatile (latching state) phase change material (PCM) in memory
applications. GeTe also exhibits a volatile (reversible state) region when heated and cooled between 100-180 °C. At
temperatures higher than 185 °C the material crystallizes and “latches” until a temperature near to its melting point (725
°C) is reached and cooled rapidly (quenching). Germanium Antimony Telluride (GeSbTe) or also known as GST has
similar characteristics as GeTe. GST also exhibits a volatile (reversible state) region when heated and cooled between
100-150 °C. GST crystallizes at 155 °C and its melting point is 600 °C. This paper demonstrates the feasibility of
fabricating radio frequency (RF) devices of phase change materials (PCM) and it also presents a comparison between
amorphous and crystalline PCMs in the RF spectrum. Previous work focuses on exploiting GeTe and GST as nonvolatile
materials in memory applications, and also on characterizing them for their electrical and mechanical properties.
The approach here focuses on fabricating RF devices and analyzing their responses. A simulation with resistor-capacitor
(RC) and resistor-inductor (RL) circuits is presented to represent the response of the RF devices under testing. The
fabrication process includes two-layer and four-layer devices on the Si wafer. PCMs are sputtered and the test pads are
deposited using electron beam evaporation. Results show that these RF devices alone can serve as a low pass filter with a
cutoff frequency of 10 MHz.
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Eduardo Barajas and Ronald A. Coutu
Phase Change Materials (PCM) fabricated in vertical structures for reconfigurable and tunable circuits
", Proc. SPIE 8973, Micromachining and Microfabrication Process Technology XIX, 89730G (March 7, 2014); doi:10.1117/12.2037372; http://dx.doi.org/10.1117/12.2037372