Ultrahigh and microwave frequency nanomechanical systems

Nanodevices that operate with fundamental frequencies in the previously inaccessible microwave range (greater than 1 gigahertz) have been constructed. Two advances have been crucial to breaking the 1-GHz barrier in nanoelectromechanical systems (NEMS): the use of 3C-silicon carbide epilayers, and the development of balanced, high frequency displacement transducers. This achievement represents a significant advance in the quest for extremely high frequency nanoelectromechanical systems.; However, silicon carbide nanomechanical resonators with fundamental frequencies in the ultrahigh frequency and microwave range have exhibited deteriorating quality factors compared to devices at lower frequencies. Our experiments have established a strong correlation between silicon carbide surface roughness and deteriorating quality factor. Also, dissipation in such devices increases as the aspect ratio of the doubly clamped beams is reduced. Further, we have demonstrated that the SiC free-free beam nanomechanical resonators offer significant improvement in quality factor compared to doubly clamped beam design operating at similar frequencies.; Apart from 3C-SiC epilayers on silicon, polished 6H-SiC bulk material based NEMS are also made possible by our invention. A tilted Electron Cyclotron Resonance (ECR) etching technique has been developed to fabricate suspended nanomechanical structures from bulk 6H-SiC wafers.; Magnetomotive transduction has been used extensively in the above achievements. Silicon carbide material is used to create a dummy nanotube, and in turn being used to investigate the role of eddy current damping in magnetomotive transduction in the context of studying nanotube mechanical motion.; Another nanotube-based novel device structure, using a nanotube carrying a single domain nanomagnet paddle, forming a torsional mechanical resonator, has been designed and analyzed. This device design appears capable of force sensing in zeptoNewton/Hz1/2 range at room temperature.; As we cool down GHz nanomechanical resonators to low temperatures, the devices approach their quantum regime of operation. A structure designed to enable observation of quantum jumps in nanomechamcal devices is described. A prototype device demonstrating a frequency shift transduction scheme is fabricated and tested in the classical domain.