EAGER: Exploring Graphene Mechanical Switch for Future RF ICs

Project Title: EAGER: Exploring Graphene Mechanical Switch for Future RF ICs (Proposal #: 2302688; PI: Albert Wang) Proliferation of wireless communications, enabled by semiconductor radio-frequency integrated circuits, has forever changed our life. Today, it is hardly to imagine a life without smartphone and wireless internet. The current pursuit for an “always connected” world in the emerging era of internet of everything demands for new generation (Next-G) wireless technologies, beyond the fifth generation (5G), which depends upon advanced radio-frequency integrated circuit chips to support higher frequencies, broader bandwidth, and more spectrum bands in order to achieve higher data rates, lower power consumption and shorter system latency. Imagine hundreds of users in the same area utilizing smartphones at the same time, how to avoid crosstalk in between? This is where a radio-frequency switch device will play a critical role in modern wireless communications, especially for Next-G wireless system. Unfortunately, the traditional semiconductor transistor based radio-frequency switch could not support Next-G wireless communications due to its inherent technical problems, such as poor crosstalk immunity and high signal loss, which will be addressed by the proposed research. This project will explore a disruptively new radio-frequency switch technology that utilizes a novel graphene-based microelectromechanical system switch to be designed and heterogeneous integrated into semiconductor integrated circuit platform to realize a new breed of switch devices featuring ultrahigh crosstalk isolation, ultralow signal propagation loss, ultrafast switching speed to support Next-G wireless communications. This two-year EAGER proposal will explore a revolutionarily new graphene-based mechanical switch concept to address the fundamental technical challenges inherent to semiconductor field-effect transistor (FET) based radio-frequency (RF) switch technologies, including poor isolation, high insertion loss, not suitable for next-generation (Next-G) wireless communications. The proposed new transfer-free graphene based bridge-contact mechanical switch (gSwitch) device structure will be designed and fabricated in complementary metal-oxide-semiconductor (CMOS) integrated circuit (IC) platform (CMOS-gSwitch) using heterogeneous integration (HI) technology. gSwitch device represents a disruptively new switching device with several novelties: gSwitch utilizes electrostatic actuation and bridge-contact ohmic contact on/off switching mechanisms to possibly realize an ideal switch with ultrahigh isolation in OFF state, super low insertion loss in ON state and negligible power consumption. The light mass density and high Young’s modulus of graphene membrane can potentially achieve pico-second level switching speed. The bridge-contact structure can potentially prevent the stiction problem. The excellent mechanical strength of graphene may ensure high endurance of gSwitch devices supporting billion switching cycles. This project has several tasks: Task-1 to prove the new gSwitch device concept; Task-2 to develop wafer-scale transfer-free metal-carbon-insulator interface based graphene-on-silicondioxide synthesis technology for making gSwitch devices on silicon wafers; Task-3 to develop a HI fabrication flow to integrate new gSwitch devices into CMOS; Task-4 to demonstrate RF switch ICs using gSwitch for Next-G systems; Task-5 to demonstrate a frequency mixer using gSwitch. Integrated research-education activities are planned. If successful, the societal impacts will be significant by always-connecting the world for unlimited internet of everything (IoET) applications, contributing to reduce the global wireless disparity. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.