Sub-femtosecond figure-of-merit millimeter-wave switches via solution-processed MoS₂ for 6G radio-frequency front-ends.

Abstract

Next-generation 6G communication requires radio-frequency components capable of operating above 100 GHz with low loss, high isolation, and zero static power-requirements that challenge complementary metal-oxide-semiconductor (CMOS) and microelectromechanical systems (MEMS) technologies. Here, we report transfer-free, large-area millimeter-wave (mmWave) switches based on solution-processed MoS₂. While solution-processed 2D materials are often viewed as inferior to their crystalline counterparts due to high defect densities, we demonstrate that their edge-rich morphology is, in fact, a performance enabler. These edge defects act as intrinsic templates that confine Cu-filament pathways, enabling rapid (76 ns) and low-energy switching (1.57 nJ) with > 2000 cycles and uniform zero static-power operation, as corroborated by Kelvin probe force microscopy, conductive atomic force microscopy and low-temperature studies. The resulting switches achieve an low insertion loss ( < 0.1 dB) and high isolation ( > 35 dB) at 67 GHz. Notably, they exhibit a switching figure-of-merit (R_ON·C_OFF) of ~ 0.8 fs (f_co ~ 187 THz), surpassing previously reported 2D switches. Importantly, by adopting an inverse-state operational scheme in a SHUNT architecture, we mitigate self-switching and achieve improved power handling (P_0.1dB > 10 dBm) and linearity (IIP3 > 42.1 dBm). Finally, we demonstrate the platform's circuit-level viability by integrating the switches into a true-time-delay and hybrid-coupled phase shifters targeting 30 GHz mmWave applications.