ICMCTF2008 Session B4: Laser and Ion Beam Surface Engineering

The use of lasers for processing materials in thin film form has been the subject of intense study over the past 20 years. From its early applications in high temperature superconductivity, pulsed laser deposition or PLD, was recognized as an excellent technique for the fast and reproducible growth of thin films of complex oxides. Since then, PLD and other laser-based techniques have been used in the deposition of insulators, semiconductors, metals, superconductors, polymers and biological materials. At the Naval Research Laboratory, we have employed various of these techniques to fabricate structures capable of transmitting both electricity and light such as transparent semiconductive oxides, store energy such as microbatteries, and laser print patterns in non-lithographic ways such as interconnects for microelectronics. All these structures share in common the ability to be finely tuned by adjusting the parameters of the laser processing conditions, thus allowing their adaptation to a specific application. This presentation will provide an overview of recent results at the Naval Research Laboratory in laser deposition of materials in thin film form as well as laser processing of 3-dimensional patterns of nanoparticles. Examples of the various types of devices fabricated from theses structures will be presented and their performance will be discussed.

This work was supported by the Office of Naval Research.

Thin-film coatings such as MoS₂ have been been studied for a number of years as a self-lubricating wear-resistant film for a number of applications. We are exploring the addition of Ti to both MoS₂ and WS₂ films in order to improve their friction behavior under humid conditions. The films are formed by ablation of alternating Ti and WS₂ or MoS₂ targets by high-power pulsed ion beams from the 750 kV RHEPP-1 facility at Sandia National Laboratories. The individual deposited layers from each pulse are between 5-20 nm in thickness. The beam fluence of up to 10 J/cm² is used to ablate either a composite Ti/metalS₂ target, or ablate alternately two discrete targets. The depositional substrate is either at room temperature, or heated to 350° C. Although Ti is the primary admixed metal, other metals such as Ni may be investigated. When MoS₂/Ti interlayered films are deposited with a substrate temperature of 350° C, an array of 100 nm-sized single crystal Mo spheres are observed to be formed. Such films demonstrate low wear and good friction behavior under conditions of 50% relative humidity. Films made at room temperature, or from a composite MoS₂-Ti ablation target do not demonstrate this low-wear/friction behavior. Further Pin-on-disk testing, SEM, and XTEM of these films is planned to determine the cause for the difference in performance. Films of WS₂/Ti are planned as a comparison.

¹Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Co., under US DOE Contract DE-AC04-94AL85000.