Nanoelectromechanical Devices Based on Suspended Carbon Nanotube and Ge Nanowire Field Effect Transistors

Figure 1: Scanning electron microscope image close-up of the trench, electrodes, and catalyst pads. The line outlining the trench shows the extent of the wet-etch undercut. Abstract: Semi-conducting carbon nanotubes (CNT) and germanium nanowires (GNWs) are desirable fieldeffect transistor (FET) elements because of their unique electrical properties and physical stability. Previous electromechanical measurements on CVDgrown suspended carbon nanotubes have shown that the band-gap of the tube can grow or shrink depending upon both the tube’s chirality and on a tensile or perpendicular force from an AFM tip. Shorter and smaller diameter PECVD-grown tubes exhibit higher percentages of semi-conducting rather than metallic tubes. We are developing a process to suspend PECVD-grown nanotubes and germanium nanowires in FETs and to make similar measurements to determine the mechanical as well as electromechanical properties of nanotubes and nanowires. We will be investigating the compatibility of PECVD with previous techniques for measuring CVD-grown tubes by first fabricating and then measuring nanotube devices. In parallel, we will explore techniques to suspend nanowires in FETs, which has not yet been accomplished. AFM cantilever deflection and I-V g curves will be used to obtain results.