Hybrid integration of nanowire resonator arrays

This thesis describes the development and demonstration of a new hybrid integration method to fabricate nanomechanical resonator arrays using nanowires. This integration method combined techniques in off-chip synthesis and on-chip assembly of the nanowire materials. By combining AC electric-field assisted assembly of nanowire arrays, photolithographic patterning, and electrodeposition, this method enabled the parallel placement and secure clamping of individual nanowires on a pre-patterned substrate to create the nanoresonator arrays. Importantly, this method was compatible with probe-molecule (e.g., peptide nucleic acid) functionalized nanowires and it will therefore facilitate the development of chip-based multiple-target biosensor arrays.;The performance of the resonators fabricated by this new hybrid integration method was studied by measuring single silicon (Si), rhodium (Rh), and gold (Au) nanowire resonators at room temperature as a function of pressure. The resonators were characterized by using either the piezo-disk or electrostatic actuation to drive and the optical method to detect the displacement of the nanowire. The measurements in vacuum were used to investigate the mechanical properties of nanowire materials and the uniformity of the new clamping method as well. Resonators of all three materials could be described as linear oscillators with high quality (Q-) factors of 3500--5400 for Si, 1000--1300 for Rh, and 600--950 for Au nanowires. Nanowire resonators of these three materials with diameters of ∼300 nm yielded Young's modulus values of 152 +/- 6 GPa for Si, 222 +/- 70 GPa for Rh and 44 +/- 12 GPa for Au, which are all lower than the corresponding values obtained from bulk materials.;Another aspect of this thesis research was the investigation of the AC electric-field assisted assembly of nanowires that was conducted through experimental and modeling studies to understand the fundamental parameters of the nanowire array assembly and to increase on-chip nanowire assembly control and yield. These studies included describing the uniform separation observed between adjacent nanowires assembled on pairs of biased electrodes, the self-centering of nanowires across these electrodes, and the end-to-end chaining of nanowires at high concentrations. Two methods were investigated to control the precise position of single nanowires on a chip over large area (>1 cm2) with high yield (>80%). An extension to this basic AC electric-field assisted assembly process for selective placement of different types of nanowires in different and predefined locations on the chip was also demonstrated.;The research described in this thesis is general and capable to be used for a variety of off-chip synthesized materials, which will extend the scope of on-chip nanowire device applications.