If I know the thickness of the film (15nm). How I can justify about the deposition rate of the material ? Which formula or which method??
Please help
The easiest estimation is of couse a time averaged deposition rate, where you calculate the deposition rate per pulse (e.g. in Angstrom/pulse) and then you multiply that by the laser repetition rate (in pulses/second). But what you are after at is probably the instantaneous deposition rate within an individual pulse. This is of couse much larger as the individual laser pulse is typically only several 10 ns short. As most of the material ablates during the duration of the laser pulse a very rough upper limit for the instantaneous deposition rate is given by dividing the deposition rate per pulse by the duration of the laser pulse. A more precise estimate, however, needs to take into account the time evolution of the temperature profile at the taget and the velocity distribution of the plasma ions during their path to the substrate. The latter can, e.g. be obtained by time-of-flight (TOF) measurements. A good publication dealing with this subject is Fähler&Krebs, Appl. Surf. Science 96 (1996) 61.
film thickness is the integration of deposition rate with respect time. if you use the PLD for depositing nanofilm, I think the rate is constant due to low thickness and short time or number of pulses.
Thanks to both... @ Volker can you please explain how to make a rough estimation if thicknes is 15nm , and number of pulses are 20,000. with pulse duration of 20ns.
i mean i need some calculation about deposition rate per pulse..?
Dear Ali,
obviously, your deposition per pulse is 15nm/20000pulses = 0.0075 Angstrom/pulse. This is actually a rather low value for PLD, which could mean that your energy density in the laser spot does hardly exceed the ablation threshold or that the imaging conditions are not well chosen. You may want to look into the attached publication for more information. Anyway, if you are interested in the time averaged deposition rate you can muliply this number with the repetition rate of your laser (e.g. if you use 10 Hz = 10 /s, then the averaged deposition rate is 0.075 Angstrom/s).
If you are asking for the instantaneous deposition rate (within a pulse) it is of the order of 1E3 Angstrom/s, assuming that the material of one pulse arrives at the substrate in a time interval of some tenth of a millisecond (which is a more appropriate number than using 20 ns).
Article Pulsed laser deposition of metals: Consequences of the energ...
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