The effects of UV laser irradiation on the filament-assisted deposition of diamond

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Abstract
The effects of 193 and 308 nm excimer laser radiation on the filament-assisted chemical vapor deposition (CVD) of diamond were investigated, in attempts to reproduce and quantify the reported mechanism of laser-enhanced diamond deposition. The deposited materials were analyzed using optical microscopy, SEM, scanning Auger microprobe, and micro-Raman scattering. With fluence levels of >50 mJ · cm−2, UV laser irradiation was found to suppress rather than enhance the quantity of diamond deposition. The size, morphology, and Raman spectra of crystallites in the irradiated regions were nearly identical to those in adjacent unirradiated regions of the same sample. An additional laser-induced effect was a region of enhanced etching on the Si substrate, which appeared as a “shadowing” of the diamond crystallites. The results are interpreted in terms of a laser-induced depletion of diamond nucleation sites, and suggest a new method for patterning of CVD films.