A comparative study of laser- and electric-field-induced effects on the crystallinity, surface morphology and plasmon resonance of indium and gold thin films

Abstract

The effects of post-deposition treatment of In and Au thin films by excimer laser and electric field are reported. The films were subjected to an electric field in the range of 0.1-3.3 kV/cm and laser irradiation in the range from 0.01 to 0.1 J/cm 2. The effect of this treatment on the morphology and crystallinity of indium and gold thin films (10-100 nm thickness) is investigated. Indium films exhibited a three-fold grain growth at an electric field of 3.3 kV/cm. Gold thin film, on the other hand, showed significant grain growthatamuch lowerfieldof 0.6 kV/cm. The as-deposited thin films of indium and gold were amorphous but turned nanocrystalline with average crystallite sizes of 57 nm at 3.33 kV/cm and 35nm at 0.66 kV/cm, respectively. When indium thin films were laser irradiated, flat disc-shaped grains for as-deposited thin films were transformed to spherical grains at a laser fluence of 0.02 J/cm 2 and cubical grains at 0.05 J/cm 2. At 0.05 J/cm 2, as-deposited amorphous indium and gold thin films turned nanocrystalline with crystallite sizes of 50 nm and 10 nm, respectively. Significantly, laser treatment causes the grain-size distribution to become narrower with a shift in mean size to larger values. Electric-field treatment on the other hand leads to a shifting of the mean grain size to larger values without affecting the distribution. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.