Effect of UV irradiation on the structural, optical and electrical properties of platinum

Abstract

Investigations are performed on thermal, optical and electrical response of UV laser-irradiated platinum (Pt). 4N pure, annealed and fine polished samples are exposed to the KrF Excimer laser (248 nm, 20 ns, 50 mJ) under vacuum ∼10⁻⁶ torr at different laser fluences (0.5–2.5 J/cm²). Space-resolved plasma plume dynamics is studied by analyzing the captured plume images with the help of a computer controlled image-grabbing system. The irradiated targets are characterized for surface morphology, structural, optical and electrical investigations using the diagnostics; scanning electron microscopy, X-ray diffraction, rotating compensator auto-aligned ellipsometer and four-point probe, respectively. The value of maximum intensity emitted by Pt plasma plume is 250 grey scales. Surfaces of the target metals are modified by craters, moltens and redeposited material. Laser-induced periodic surface structures are produced at low laser fluence. Irradiation of Pt causes changes in diffracted X-rays intensity and grain sizes, dislocation in line densities and strain in the target materials. Considerable changes occur in optical parameters as well. A decrease in electrical conductivity of the irradiated targets also takes place in an exponential way with the change in laser fluence.

Keywords:

• plasma plume
• surface morphology
• structural analysis
• optical parameters
• electrical conductivity