Contribution of high-velocity particles to stress of thin film produced by laser ablation

The origin of stress in thin CuInSe2 films produced by laser ablation is investigated by the observation of the laser plume using the multichannel spectrometer and the laser transmittance method. As the laser energy density on the target increases above 1J/cm(2), the fraction of fast particles (atoms and ions) decreases and that of slow particles (droplets) increases. The stress in the thin film is the greatest at 1 J/cm(2), and decreases below and above 1J/cm(2). From these results it is clear that the compressive stress of the thin film is caused by the peening effect due to the incidence of fast atoms and ions, and the slow, heavy species contribute to the relaxation of stress.