Papers by Author: Eun Kyung Suh

Abstract: We report on investigation of the AC dielectrophoresis aligned assembly deposition (DAAD) of gallium nitride nanowires (GaN NWs) with both the variation of the electric field and the frequency. Our DAAD methods were used to align and manipulate GaN nanowires as well as to extract the electrical properties of semiconducting nanowires. We observed that the ability of the alignment strongly depends on the magnitude of the AC electric field and frequencies. For the higher AC peak-to-peak electric fields (up to 20 Vp-p), the GaN nanowires have a better alignment across the patterned Ti / Au electrodes with a high yield rate of ~ 90% over the entire arrays (in our case, 20 arrays) in the chip at the 20 kHz. From the transport measurements of our AC aligned GaN nanowires using conventional three-probe schemes in field-effect transistor structures, we found that the conductance of the GaN NWs increased for gating voltage greater than zero and decreased for gating voltage less than zero, indicating these GaN nanowires have n-type dopants.

Abstract: We report on simple techniques for extracting the electrical properties of 1-dimensional semiconductor nanowires using standard ultraviolet (UV) photo-lithography instead of e-beam lithography (EBL), which is a commonly used technique for the fabrication of nanoscale electrical devices. For electrical transport measurement the gallium nitride nanowires (GaN NWs) were prepared by a horizontal hot-wall chemical vapor deposition (CVD) with metallic Ga and NH3 gas for Ga and N sources, and GaN nanowire field effect transistor (FET) structures on a 8×8 mm2 silicon wafer were fabricated by ordinary 2-mask photo-lithography processes. The estimated carrier mobility from the gate-modulation characteristics is on the order of 60 ∼ 70 cm2/V⋅s. We found that our approach is a powerful and simple technique to extract the electrical properties of semiconductor nanowires. The material characteristics of GaN nanowires are also discussed.