Analysis of diamond film creation by pulsed optical lattices Ryan P. Jansen a , Sergey F. Gimelshein a, ⁎, Mikhail N. Shneider b a University of Southern California, Los Angeles, CA 90089, United States b Princeton University, Princeton, NJ 08544, United States abstract article info Article history: Received 12 May 2009 Received in revised form 7 October 2009 Accepted 22 October 2009 Available online 10 November 2009 Keywords: Diamond film DSMC Molecular beam Fullerene The ability of a chirped pulsed optical lattice to create diamond films using a molecular beam of fullerene molecules is numerically investigated. Two cases, high and low density, are considered. In both cases, the molecular beam was found to impact the substrate at velocities between 10 and 14 km/s. The proposed scenario for the diamond coating stems from the generation of high velocity beams of fullerene particles, bombardment of the substrate surface by these beams, successive dissipation of kinetic energy at the surface and drastic increase of pressure and temperature in the interaction region and finally, formation of diamond crystal structure from deposited fullerenes. A possible setup for the film deposition is proposed. It is shown that that such a system could possibly achieve diamond film growth rates in excess of 1.4 mm/s. © 2009 Elsevier B.V. All rights reserved. 1. Introduction High thermal conductivity and exceptional hardness are the characteristics of diamond that make it desirable for a number of industrial and optical applications. The use of graphite for diamond production is problematic since the phase change occurs at extremely large pressures and temperatures. Adding fullerenes to graphite allows one to reduce the pressures required for diamond production, but they are still high. Over 4.5 GPa pressures were used in [1]. Direct conversion of fullerenes to diamond has also been observed at room temperature, but even higher pressures of about 25 GPa are necessary [2]. These methods do not allow for the production of precise diamond films needed in many applications. One of the most widely used and studied approaches for creating diamond films is chemical vapor deposition (CVD) [3]. In a CVD process, gas-phase carbon- containing precursor molecules are thermally or plasma activated. Diamond nucleation and growth on the substrate is maintained at gas pressures about or below 1 atm and surface temperatures on the order of 1000 °C [4]. A slightly lower substrate temperature was used by [5], around 750 °C, at very low pressures around 30 Torr. However, this process involved an intensive substrate preparation process. The activation process therefore allows one to avoid the extremely large pressures that would otherwise be required to convert graphite to diamond. However, the diamond growth rates in CVD processes are still relatively slow. For high quality films, growth rates of up to 8 μm/h have been reported [6]. For low quality films produced with combustion methods, growth rates are between 100 and 1000 μm/h [3]. Molecular beams may present an alternative approach to deposit high quality films at relatively high rates [7]. Generally, there are several techniques to create molecular beams. First is ion-plasma deposition, where a film coating is produced by sputtering a target material in an inert gas plasma when a negative electric potential is applied to the target. Another deposition technology is reactive ion- plasma deposition: films are formed through chemical interaction of the sputtered material and the reactive gas, usually on the target surface. The principal drawbacks of plasma chemical material depositions are inherent surface charging, undesirable decomposition of molecules of material, large operating volumes, low selectivity, relatively low directionality, and limited energy control. Gasdynamic generation of high-energy molecular beams avoid some of the above drawbacks, primarily surface charging and decomposition. In gasdynamic beam generation, the beam is formed by high velocity neutrals. There are a number of gasdynamics techniques being used, the most important of which are effusion, nozzle plumes with skimmers, and impulse gasdynamic sources with various activation mechanisms. The main disadvantage of the gasdynamic methods of beam generation is relatively low energy of carrier molecules, usually less than 1 eV for continuous sources, and less than 3 eV for pulsed sources. These energies are too low to be used for the creation of diamond films. A way to create a neutral molecular beam with a higher energy is to use a pulsed optical lattice. An optical lattice is created by two intersecting counter-propagating laser fields, and is characterized by an interaction between polarizable particles and the field of the optical interference pattern. A moving lattice is made by a frequency Diamond & Related Materials 19 (2010) 50–55 ⁎ Corresponding author. E-mail address: gimelshe@usc.edu (S.F. Gimelshein). 0925-9635/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.diamond.2009.10.022 Contents lists available at ScienceDirect Diamond & Related Materials journal homepage: www.elsevier.com/locate/diamond