Plume expansion and stoichiometry in the growth of multi-component thin films using dual-laser ablation

The application of dual-laser ablation for the growth of ZnO and multi-component films of CuIn0.75.Ca0.25Se2 is presented. Comparison of the optical emission from the ZnO plume under dual-laser and single excimer laser ablation reveals that the coupling of the CO2 laser into the excimer laser-ablated plume causes both significant ionic excitation as well as lateral plume expansion. The cos(21)(theta) thickness profile of the single laser film transforms to a more uniform cos(6)(theta) for dual-laser ablation. A comparison of the enhancement of film uniformity at different CO2 laser fluences shows that increasing the CO2 laser energy leads to greater film uniformity in dual-laser ablation. The advantages of the growth of multi-component materials using dual-laser ablation are demonstrated by optical plume analysis and the deposition of CuIn0.75Ga0.25Se2 films. (C) 1998 Elsevier Science B.V.