Characterisation of laser-treated Ag, Al, and Al/Ag metal thin films deposited by DC sputtering

Abstract

Structural, optical and electrical properties of Nd:YAG pulsed laser-treated silver (Ag), Aluminium (Al) and Al/Ag bi-layer metal thin films deposited by Direct Current (DC) sputtering technique is investigated. Laser-metal interaction treatment as an alternative to temperature annealing was used to treat the surface of the metal thin films. Measurements from X-ray Diffraction (XRD) indicated an enhanced grain growth and crystallisation for the laser-treated thin films with strong and dominant Ag diffraction peaks at (111) and (200) crystal planes from Ag and Al/Ag films. The surface roughness of Ag and Al thin films increased when exposed to 120 mJ laser energy as measured by Atomic Force Microscopy (AFM). However, smooth surface and reduction in surface roughness were observed when under-layer Al film was deposited below the Ag thin films (Al/Ag bi-layer). The bi-layer Al/Ag film shows a reduced reflectance in most of the visible range as determined by UV-vis spectrophotometer. Surface to volume atomic ratio of the laser-treated films increased with a decrease in resistivity as examined by four-point probes. All the Nd:YAG laser-treated metal films show a significant decrease in resistivity, sheet resistance and optical reflectance indicating possible application as intermediate layer in transparent conductive oxide (TCO/Metal/TCO) electrode for solar cell devices.