Fabrication and characterization of single bismuth nanowire

This thesis discusses the fabrication and transport study of single bismuth (Bi) nanowire. It covers low energy electron beam lithography for fabricating Bi nanowires and transport measurements of single Bi nanowire.; In the nanometer-scale lithography, low energy electron beam lithography with silver (Ag) nanocrystal wires and silicon (Si) nanowires is demonstrated. The Langmuir technique was utilized to form high aspect ratio lamellae or wire patterns, of Ag nanocrystals at the air/water interface, and these patterns were transferred onto resist-coated single crystal Bi/CdTe substrates as a Langmuir-Schaeffer film and as a shadowmask. The wire patterns were transferred to the photoresist material by spatially selective electron beam exposure on the Ag nanocrystal wire shadowmask. Similarly, Si nanowires prepared by VLS (Vapor-Liquid-Solid) process were also used as a shadowmask. 50 nm and 30 nm widths of Bi nanowires were successfully fabricated with a subsequent reactive ion etching (RIE) process.; In the transport study of Bi single nanowire, measurements of the electrical conductivity of single Bi nanowire, were made. Submicron-size metal contacts on the Bi single nanowire could be prepared by in-situ Focused Ion Beam (FEB) ion induced metal deposition. The examined nanowires have characteristic dimensions slightly below the critical diameter D (∼50nm) at which a phase transition semimetal to semiconductor was predicted to occur. The results revealed that semiconductor-like temperature dependence of the electrical conductivity of a Bi nanowire, which is strikingly different from its bulk dependence. A theoretical model was also developed to describe the dependence of the electrical conductivity and energy band gap on the diameter of Bi nanowires. Overlap energy of semiconducting Bi nanowire as estimated by the results of the measurements on the single nanowire corresponds to the theoretical model.; Demonstrated new lithography technique may be a good candidate as a low-cost fabrication technique for semiconductor nanometer-scale structures and presented experimental data of Bi nanowires may be crucial for suggested thermoelectric application of Bi nanowires.