Radio Frequency Transistors and Circuits Based on CVD MoS2.

We report on the gigahertz radio frequency (RF) performance of chemical vapor deposited (CVD) monolayer MoS2 field-effect transistors (FETs). Initial DC characterizations of fabricated MoS2 FETs yielded current densities exceeding 200 µA/µm and maximum transconductance of 38 µS/µm. A contact resistance corrected low-field mobility of 55 cm(2)/(V s) was achieved. Radio frequency FETs were fabricated in the ground-signal-ground (GSG) layout, and standard de-embedding techniques were applied. Operating at the peak transconductance, we obtain short-circuit current-gain intrinsic cutoff frequency, fT, of 6.7 GHz and maximum intrinsic oscillation frequency, fmax, of 5.3 GHz for a device with a gate length of 250 nm. The MoS2 device afforded an extrinsic voltage gain Av of 6 dB at 100 MHz with voltage amplification until 3 GHz. With the as-measured frequency performance of CVD MoS2, we provide the first demonstration of a common-source (CS) amplifier with voltage gain of 14 dB and an active frequency mixer with conversion gain of -15 dB. Our results of gigahertz frequency performance as well as analog circuit operation show that large area CVD MoS2 may be suitable for industrial-scale electronic applications.

Large-Area Monolayer MoS2 for Flexible Low-Power RF Nanoelectronics in the GHz Regime.

Flexible synthesized MoS2 transistors are advanced to perform at GHz speeds. An intrinsic cutoff frequency of 5.6 GHz is achieved and analog circuits are realized. Devices are mechanically robust for 10,000 bending cycles.

Dual-band moiré metasurface patches for multifunctional biomedical applications.

There has been strong interest in developing multi-band plasmonic metasurfaces for multiple optical functions on single platforms. Herein, we developed Au moiré metasurface patches (AMMP), which leverage the tunable multi-band responses of Au moiré metasurfaces and the additional field enhancements of the metal-insulator-metal configuration to achieve dual-band plasmon resonance modes in near-infrared and mid-infrared regimes with high field enhancement. Furthermore, we demonstrate the multifunctional applications of AMMP, including surface-enhanced infrared spectroscopy, optical capture and patterning of bacteria, and photothermal denaturation of proteins. With their multiple functions of high performance, in combination with cost-effective fabrication using moiré nanosphere lithography, the AMMP will enable the development of highly integrated biophotonic platforms for a wide range of applications in disease theranostics, sterilization, and the study of microbiomes.