High Speed Terahertz Devices via Emerging Hybrid GNRFET/Josephson Junction Technologies

Abstract

An approach to merge superconducting Josephson junction (JJ) devices with nanoscale Graphene devices in order to achieve high gain-bandwidth-product on the order of THz is proposed. While JJ-based devices have existed since nearly 1962, interfacing or interacting with them with standard electrical systems has been a challenge for several reasons, including operating temperature, switching speed, and low-signal sensitivity. In this article, we investigated the possibility of utilizing JJ's so-called ac effect in order to generate high frequency signals that can be accommodated by high speed nanoscale devices. Graphene nanoribbon field effect transistors (GNRFET) have been emphasized for their very high frequency operation that is appropriate to accommodate the very high switching speed of the JJ devices. The article is based on the ac JJ effect with generating a sinusoidal current whose frequency directly scales with voltage. For a single-stage GNRFET CS amplifier, a gain of 35.7 dB with a bandwidth of 217 GHz was achieved, while 10.8 dB with a unitary gain of 2.5 THz was also accomplished. This article details the design and interface of the JJ with GNRFET devices, targeting high frequency signal generation on the order of hundreds of GHz to THz, with the purpose of providing a foundation on top of which further developments can be made, especially in the areas of communications, medical devices, instrumentation and measurement devices, high-speed imaging, subinfrared antenna arrays, and computer architecture and hardware, by providing a system, which can respond to speeds on the order of fifty to one hundred times faster than current commercial computer equipment or signal generation/processing.