The aggressive scaling of complementary metal oxide semiconductor devices into the sub-100 nm region has resulted in increased short channel effects and gate oxide leakage, which causes a larger power dissipation and unsatisfactory device performance. In recent years, nanoelectromechanical systems (NEMS) have been intensively studied as a promising solution for future low power logic switches and nonvolatile memory applications due to their attractive characteristics such as abrupt switching and an extremely low OFF-state leakage current. However, current NEMS based switches suffer from a high activation voltage, low ON-state current, and large static friction, also known as stiction, which can lead to device failure

To overcome these aforementioned problems, we have tried different approaches in terms of new material and new structure. Carbon-based materials such as graphene nanoribbon have been studied. The unique material properties of bilayer graphene nanoribbon (BGNR) such as high tensile strength, large thermal conductance, and high electrical carrier mobility naturally becomes a material of interest for our research efforts in NEMS switches. BGNR is a semiconducting material with electrical properties, such as its energy bandgap, that are dependent on the ribbon width, the atomic configurations at the edges, and the interlayer distance between the monolayers. Through simulation, we find out that the on/off state of BGNR NEMS switch can be changed by sub nanometer movement.

Besides BGNR NEMS switch, several designs of M/NEMS switches which incorporate the idea of novel actuation structure are also in the pipeline. Recently, we have also demonstrated a dual-silicon-nanowires based U-shaped NEMS switch with low pull-in voltage using standard CMOS compatible process.

Selected Publications:

1. You Qian, Liang Lou, Julius Ming-Lin Tsai and Chengkuo Lee, A dual-silicon-nanowires based U-shape nanoelectromechanical switch with low pull-in voltage, Appl. Phys. Lett., vol. 100, no. 11,113102, 2012. [PDF] [DOI]
2. Kai-Tak Lam, Marie Stephen Leo, Chengkuo Lee and Gengchiau Liang, Design evaluation of graphene nanoribbon nanoelectromechanical devices, J. Appl. Phys., vol. 110, pp. 024302-024308, 2011. [PDF] [DOI]
3. Kai-Tak Lam, Chengkuo Lee and Gengchiau Liang, Bilayer Graphene Nanoribbon Nanoelectromechanical System Device: A computational study, Appl. Phys. Lett., vol. 95, 143107, 2009. [PDF] [DOI]

 

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