Laser deposition of diamondlike carbon films at high intensities

Abstract

Unhydrogenated diamondlike carbon ͑DLC͒ thin films have been deposited by laser ablation of graphite, using a high power Ti: sapphire solid state laser system. DLC films were deposited onto silicon substrates at room temperature with subpicosecond laser pulses, at peak intensities in the 4ϫ10 14-5ϫ10 15 W/cm 2 range. A variety of techniques, including scanning and transmission electron microscopy ͑SEM and TEM͒, Raman spectroscopy, spectroscopic ellipsometry ͑SE͒, and electron energy loss spectroscopy ͑EELS͒ have been used to analyze the film quality. Smooth, partially transparent films were produced, distinct from the graphite target. Sp 3 volume fractions were found to be in the 50%-60% range, with Tauc band gaps ranging from 0.6 to 1.2 eV, depending on laser intensity. Kinetic energies carried by the carbon ions in the laser induced plasma were measured through time-of-flight ͑TOF͒ spectroscopy. Their most probable kinetic energies were found to be in the 700-1000 eV range, increasing with laser intensity.

Correlation between <I>I</I><SUB>D</SUB>&frasl;<I>I</I><SUB>G</SUB> Ratio from Visible Raman Spectra and sp<SUP>2</SUP>/sp<SUP>3</SUP> Ratio from XPS Spectra of Annealed Hydrogenated DLC Film

“…[4][5][6] In finding the correlation between I D =I G ratio and sp 2 /sp 3 ratio of non-hydrogenated Diamond-Like Carbon film (DLC) film, some studies have used Raman spectra associated with EELS or XPS. [7][8][9][10][11][12] But for DLCH film, due to the spectrum of visible Raman contains a much larger scattering cross section of sp 2 than that of sp 3 up to 50-230 times, 13) it is very difficult to detect the sp 3 content when the sp 3 content in DLCH film is small. As a result, visible Raman can't be directly applied to probe sp 2 /sp 3 ratio.…”

Influence of Heat Treatment on Mechanical Properties of DLC Deposited by FIB-CVD

“…In many area of engineering applications, DLC have found as coatings for cutting tools, hard disks, metal molds and optical windows (1), (2) . Therefore, production of DLC has been investigated by a number of different methods such as vacuum evaporation (3) , laser ablation (4), (5) , magnetron sputtering (6) - (8) , chemical vapor deposition methods (9) - (11) . Recently, focused ion beam assisted CVD (FIB-CVD) method is developed as a new technique for producing of micro-and/or nano-DLC structures.…”

High spatial and temporal resolution measurement of mechanical properties in hydrogels by non-contact laser excitation

“…The momentum of the plasma plume becomes the impulse or the excitation force for the irradiated material. LA has various applications, including plasma growth, 23 LA shockwave in air, 24 LA in water, 25 cavitation bubble, 26 laser propulsion, 27,28 laser micromachining, 29 laser deposition, 30 laser peening, 31 and vibration tests and acoustic tests using LA or laser-induced breakdown (LIB). [32][33][34][35][36][37][38][39][40][41] Although multiple stress waves in silica glass generated by femtosecond LA 20 have been visualized using the shadowgraph technique, using LA as an excitation force for gels has yet to be investigated.…”