Nano-Electromechanical Active Resonant Devices
Over the last three decades, various functionalities ranging from frequency selection and timing to sensing and actuation have been successfully demonstrated for microscale and nanoscale electromechanical systems. Although such capabilities complement solid-state electronics, enabling state-of-the-art compact and high-performance electronics, the amplification of electronic signals is an area where micro-/nano mechanics have not experienced much progress. On the other hand, channel-selective filtering and amplification in ultrahigh-frequency (UHF) receiver front-ends are crucial for the realization of cognitive radio systems and the future of wireless communication. In the past decade, there have been significant advances in the performance of microscale UHF electromechanical resonant devices. However, such devices have not yet been able to meet the requirements for direct channel selection at RF. They also occupy a relatively large area on the chip making implementation of large arrays to cover several frequency bands challenging. The main objective of this work is to demonstrate amplification of electrical signals using a very simple nanomechanical device occupying a very small footprint without using solid state transistors. It is shown that vibration amplitude amplification using a combination of mechanical resonance and piezoresistive internal amplification can turn the relatively weak piezoresistivity of silicon into a viable electronic amplification mechanism. With its inherent frequency selective nature, such mechanism can also address the need for ultranarrow-band filtering along with the amplification of low power signals in wireless communications and certain sensing applications. Finally, using the presented electromechanical model and the fabricated nano-scale devices it is demonstrated that the performance of the proposed nano-electromechanical active resonant devices improves significantly as the dimensions are reduced to the nanoscale, presenting a potential pathway toward deep-nanoscale electronics.