NOVEL MATERIALS APPLICATIONS OF PULSED LASER DEPOSITION

The four groups of materials discussed in this article illustrate that even widely disparate physical/chemical natures and applications can readily benefit from pulsed laser deposition to form thin films. Ferroelectrics, bioceramics, and ferrites are all complex, multicomponent oxides equivalent in structure or complexity to the oxide superconductors. As such, they benefit from the same advantages PLD offers to the growth of high-temperature superconducting films. While tribological materials, in general, are not complex oxides, PLD has produced improved properties for these films, too. A notable example is the production of epitaxial c-BN on Si by PLD. Perhaps the most useful feature of PLD is the congruent nature of the laser evaporation process that leads to the ability to reproduce complex target stoichiometries. Also important is the ability to deposit films in reactive gas environments. This feature enables deposited films to retain the correct stoichiometry and crystal structure during growth. Conventional thin film deposition methods that require a heated filament cannot tolerate such high pressures of reactive gases. Additional important features of PLD include: high film purity (due to the small spot focus of the laser on target which limits chamber heating), a relatively simple and inexpensive deposition apparatus, and a high instantaneous rate of deposition (as high as 106 A/s). Since 1987, when high Tc superconductors focused attention on PLD, there has been dramatic growth in the number of materials deposited using the technique and the number of laboratories becoming involved in PLD process development. These trends are resulting in the application of PLD to an ever-broadening spectrum of materials. Continued improvements to the process (e.g., substrate biasing and the use of filaments or ion sources) can be expected as new and more complex materials present challenges to push the limits of the PLD technique. © 1992, Materials Research Society. All rights reserved.