(a) The experimental setup of the dc biased PLD experiments; (b) schematic representation of the conventional PLD experiments: the laser beam produces various ions and clusters of the form ( depending on laser wavelength and fluence) and , which move toward the substrate; (c) the dc voltage prevents the electron radiation of the substrate and orients and accelerates the ions to the desired kinetic energy toward the substrate.
(a) Representative experimental XRR scans, in the form of , from two ta-C films grown by PLD with (open circles, indicated as dc PLD) and without (solid squares) static electric field. (b) The inset shows details around the critical angles; the difference in critical angle corresponds to a density difference of .
Representative experimental XRR scan (EXP) from a ta-C film grown by PLD and the respective simulated curve (SIM) (this curve is shifted to lower values to better illustrate its features) using Parrat’s formulation determining density .
The variation of the film density with the dc voltage for the Nd:YAG: (a) first, (b) second, and (b) third harmonics of the Nd:YAG laser. The plasmon energies of selected samples are also shown as open triangles.
The density of and ta-C films grown by PLD vs the wavelength used for the ablation. Data from Ref. 29 and for lower fluence are shown for comparison. The dotted horizontal lines indicate the density of crystalline graphite and diamond.
The growth rate vs the applied voltage for the three sets of and ta-C films.
The variation of surface roughness vs the applied voltage for the three sets of and ta-C films.
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