We report on an experimental demonstration of graphene-metal ohmic contacts with contact resistance below 100 Ω µm. These have been fabricated on graphene wafers, both with and without hydrogen intercalation, and measured using the transmission line method. Specific contact resistivities of 3 × 10−7 to 1.2 × 10−8 Ω cm2 have been obtained. The ultra-low contact resistance yielded short-channel (source-drain distance of 0.45 µm) HfO2/graphene field effect transistors (FETs) with a low on-resistance (Ron) of 550 Ω µm and a high current density of 1.7 A/mm at a source-drain voltage of 1 V. These values represent state-of-the-art (SOA) performance in graphene-metal contacts and graphene FETs. This ohmic contact resistance is comparable to that of SOA high-speed III–V high electron mobility transistors.
We report on GeTe-based, phase-change RF switches in a series configuration with an embedded micro heater for thermal switching. With heater parasitics reduced, these GeTe RF switches show on-state resistance of 0.12 ohm*mm and off-state capacitance of 0.12 pF/mm. The RF switch figure-of-merit is estimated to be 11 THz, which is about 15 times better than state-of-the-art silicon-on insulator switches. With 50-J.lm-wide GeTe switches, RF insertion loss was 0.25 dB and isolation was 24 dB at 20 GHz.Harmonic powers were suppressed >90 dBc at 35 dBm, meeting wireless requirements. The GeTe switches were characterized under W-CDMA signals without spectral regrowth up to 25 dBm.
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