Kyung-Ah Son1 Hwa-Chang Seo1 Kangmu Lee1 Jeong-Sun Moon1

1, HRL Laboratories, Malibu, California, United States

Recently, phase-change materials have been explored for reconfigurable RF and electro-optic applications, which include non-volatile RF switches [1], tunable photonic devices [2], and non-volatile optical memory devices [3], for instance. Low-loss, linear RF switches are integral parts of wireless RF front-ends for antenna and filter switching, for instance. Common key features of RF switches include cost, low insertion loss, high isolation, excellent linearity, power handling, easy integration with conventional semiconductor technologies, reliability and packaging. Among various RF switch technologies, Si-based technology is widely used for wireless networks below ~5 GHz. For instance, a matured RF-SOI switch has a Ron×Coff value of ~250 femtosecond with switch FOM of 1/(2*π* Ron×Coff) ~0.6 THz. Its RF performance at mm-wave frequencies would be compromised.
In this talk, we report on the first SbTe phase-change material RF switches with a refractory TiW heater in a planar configuration. With the planar layout and heater reliability, a record switching cycle endurance of >300K was demonstrated. With on-state resistance of 0.5 ohm*mm and off-state capacitance of 75 fF/mm, the RF switch figure-of-merit (FOM) is 4.1 THz, which is 6-7 times better than state-of-the-art RF switches, including RF silicon-on-insulator technology. With further layout optimization, SbTe phase-change material RF switches could be a potential candidate for future RF switch technology.

[1] J. S. Moon et al., “11 THz figure-of-merit phase-change RF switches for reconfigurable wireless front-ends,” IEEE MTT-S Digest, pp. 1-3, 2015
[2] K.-A. Son et al., “Phase-change GeTe for Photonic Applications”, MRS Spring Meeting, 2017
[3] E. Kuramochi and M. Notomi, “Optical memory: Phase-change materials”, Nature Photonics, pp. 712-714, 2015