| The role of the background gas in pulsed-laser ablation of high quality indium-tin-oxide (ITO) films at room temperature is not totally understood, despite its technological attractiveness. In general, the interaction between the ablated species in the plume and the background gas at a specific pressure is a complex process that may involve chemical reactions at the same time as collisions. In the case of ITO fabricated by pulsed-laser deposition (PLD), oxygen has been, by far, the preferred background gas for no significant reason. This dissertation deepens the understanding of the collision and chemical mechanisms between the species in the plume and different background gases, when ITO films are obtained by PLD. Detailed stoichiometric and electrical properties in the films, supported by optical transmission and x-ray diffraction experiments, have been measured and analyzed to conclude that only reactive scattering in the plume can produce high-quality ITO by PLD at room temperature. Thus, oxygen and nitrogen produce high-quality ITO films by these means; inert gases such as helium, neon, and argon do not. A model of equilibration of ablated species by elastic collisions is developed to partially explain the conductivity in the films. We then find evidence of incorporation of the background gas into the films via chemical reactions (∼5% for nitrogen and ∼30% for oxygen in the most conductive films). In the case of oxygen as the background gas, we depict the chemical mechanisms involved in its incorporation into the ITO films by separating the oxygen contributions between the target and the background gas. Furthermore, a strong correlation of one of these chemical mechanisms with the main conduction mechanism in ITO is observed. These findings reveal the interaction between the background gas and the plume in such a way as to individually control the electronic quantities which define the conductivity. |
