Solution-Processed InAs Nanowire Transistors as Microwave Switches

The feasibility of using self-assembled InAs nanowire bottom-gated field-effect transistors as radio-frequency and microwave switches by direct integration into a transmission line is demonstrated. This proof of concept is demonstrated as a coplanar waveguide (CPW) microwave transmission line, where the nanowires function as a tunable impedance in the CPW through gate biasing. The key to this switching capability is the high-performance, low impedance InAs nanowire transistor behavior with field-effect mobility of ≈300 cm² V⁻¹ s⁻¹, on/off ratio of 10³, and resistance modulation from only 50 Ω in the full accumulation mode, to ≈50 kΩ when the nanowires are depleted of charge carriers. The gate biasing of the nanowires within the CPW results in a switching behavior, exhibited by a ≈10 dB change in the transmission coefficient, S₂₁, between the on/off switching states, over 5–33 GHz. This frequency range covers both the microwave and millimeter-wave bands dedicated to Internet of things and 5G applications. Demonstration of these switches creates opportunities for a new class of devices for microwave applications based on solution-processed semiconducting nanowires.