Characteristic features of laser-produced plasmas for thin film deposition

Abstract

Peculiarities of the pulsed laser plasma method for the deposition of thin films are demonstrated. The interaction between the laser beam and the solid target results in the generation of a plasma. The features of the laser plasma depend on the laser power density and the kind of incident laser light. The model investigations considered contain low and high temperature plasmas, which permit the evaporation threshold as well as the electron temperature and density of an absorbing laser plasma to be estimated. The change in crater depth on the target with variation of the laser flux gives information on the plasma generation and its characteristics, particle flow and energy. A set of Saha equations defines the average charge of the ions and the degree of ionization. The freezing length of particles in the laser plasma depends on their energy and can be larger than the radius of the laser spot. Deposition and growth rates on the substrate during the laser pulse are calculated and turn out to be very high in comparison with those of other deposition methods. Both the high deposition rate and the particle energy, which is transformed into lateral mobility of particles and local heating on the substrate, are the relevant parameters for a two-dimensional layer growth mode of homogeneous dense films.