Pulsed laser deposition for functional optical films

Abstract

Pulsed laser deposition is a versatile technique with high capabilities to produce complex oxide films. Several parameters must be controlled and optimised in order to achieve the desired film quality or structure, since there is a narrow range of laser energy density values, gas pressures and target-substrate distances that lead to optimum deposition conditions. The goal to reach is the control of the kinetic energy of the species arriving to the substrate to avoid undesired processes (such as surface damage or sputtering), while keeping a value high enough to enhance beneficial processes at the substrate (such as film density enhancement, surface mobility and reactivity and, in some cases, even implantation). Additionally, PLD has a high potential to produce complex glassy films for integrated optical applications with improved optical performances. The main advantages of PLD when compared to other deposition methods are the capability of producing glassy films in an extended compositional range with respect to bulk materials and the possibility of avoiding oxygen deficiencies in the glass network by using an oxygen pressure during deposition. Finally, PLD has a high potential to produce complex nanostructured films formed by layers with thicknesses ranging from submonolayers (1013 atoms cm-2 level) that can be associated to atomic doping to clusters and nanoparticles (up to 1016 atoms cm-2). The main advantages of PLD in these cases when compared to other deposition methods are the capability of producing complex oxide hosts and the possibility of structuring the distribution of the dopant in the nanometer scale in a single step process. Copyright 2007 Springer Science+Business Media LLC.