Tuesday, 12 October 2004 - 4:20 PM

This presentation is part of : Sub-wavelength Nanostructuring I

Laser-assisted local coating of DLC films on W-tips from benzene solution

Jing Shi1, Yongfeng Lu2, Ravi Shankar Cherukuri1, Kiran K Mendu2, David W. Doerr3, and Dennis R. Alexander3. (1) University of nebraska -Lincoln, 209N Walter Scott Engineering Center, P.O. Box 880511, Lincoln, NE 68588-0511, (2) University of Nebraska-Lincoln, Lincoln, NE 68502, (3) Dept. of Electrical Engineering and Center for Electro-Optics, 209N WSEC, Lincoln, NE 68588-0511

Diamond-like carbon (DLC) films were deposited on tungsten tips under KrF excimer laser irradiation in benzene solution. The deposition process was found to be highly dependent on tip sharpness. Tips with larger curvature radii and smaller aspect ratios could not be coated with DLC films under the same condition as that for sharp tips. Raman spectra showed that more sp3 tetrahedral structures were present in the DLC films on a tip with a smaller curvature radius. Simulation results showed that the tip-sharpness-dependent local optical enhancement played an important role in the DLC deposition process. An optical-field gradient from apex to tip body was also found in the simulation. We suggest that there are two modes in the process of DLC deposition on nanotips under different laser fluences, i.e. local apex DLC deposition under low laser fluences and phase-graded DLC deposition under high laser fluences. Currently, DLC coated tips are under characterization by scanning tunneling spectroscopy (STS) and transmission electron microscopy (TEM).

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