Nanoelectromechanical tunneling switches based on self-assembled molecular layers

We propose nanoelectromechanical (NEM) switches that operate via electromechanical modulation of tunneling current through several-nanometer-thick switching gaps. In such a device, direct contact between electrodes is avoided by utilizing self-assembled molecular layers to define the switching gap. Electrostatic compression of the molecular layer reduces the tunneling gap leading to an exponential increase in the tunneling current, turning on the switch. With removal of an applied voltage, the compressed layer provides the elastic restoring force necessary to overcome the surface adhesive forces, turning off the switch. Thus, the proposed tunneling NEM switch may enable low-voltage operation while simultaneously mitigating device failure due to stiction. This principle is experimentally investigated using a prototype two-terminal tunneling NEM switch with a switching gap formed by a fluorinated decanethiol layer. In this device, the presence of the molecular film promotes repeatable switching. A comparison of the switch operation with a theoretical model indicates electrostatic compression of the molecular switching gap.