Papers by Author: Kee Suk Nahm

Abstract: We demonstrate the fabrication and the electrical transport properties of single crystalline 3C silicon carbide nanowires (SiC NWs). The growth of SiC NWs was carried out in a chemical vapor deposition (CVD) furnace. Methyltrichlorosilane (MTS, CH3SiCl3) was chosen as a source precursor. SiC NWs had diameters of less than 100 nm and lengths of several μm. For electrical transport measurements, as-gown SiC NWs were prepared on a highly doped silicon wafer, pre-patterned by a photo-lithography process, with a 400 nm thick SiO2 layer. Source and drain electrodes were defined by e-beam lithography (EBL). Prior to the metal deposition (Ti/Au : 40 nm/70 nm) by thermal evaporation, the native oxide on SiC NWs was removed by buffered HF. The estimated mobility of carriers is 15 cm2/(Vs) for a source-drain voltage (VSD) of 0.02 V. It is very low compared to that expected in bulk and/or thin film 3C-SiC. The electrical measurements from nanowire-based field effect transistor (FET) structures illustrate that SiC NWs are weak n-type semiconductor. We have also demonstrated a powerful technique, a standard UV photo-lithography process, for fabrication of SiC nanowires instead of using EBL process.

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.