During Pulse Laser deposition of Pt thin film, I observe the XRD intensity continuously increasing. The number pulses are same for each deposition (which means rate of ablation is same for all deposition). If the ablation rate is same Intensity should be same for every deposited thin film but it was not. I was changing the substrate temperature form RT to 600C for each deposition. Is this question is justified by crystallinity of the thin films because i Observe that FWHM decreasing at 600C?
Hi Ali,
you gave the anwer by yourself.
The amount of deposited material should be the same as you stated. Thus you should observe about the same amount of counts in your XRD peaks. You observe decreasing peaks width vs increase of deposition temperature. You are right; crystallinity is increased due to higher deposition temperature (annealing during deposition and afterwards); what else should the XRD peak height other do then increasing in order to maintain total integral counts under the peak.
Hi Ali
i agree about what Gerhald told you, but you also can increase the peak intensities when you increase the voltage, or is increased the film thickness there are many factors, the relative intensity of the peaks and the thickness of the peak are a more interesting data.
Thanks Gerhard .. and @Iker Rodrigo If the deposition rate of material is same for each temperature then thickness should remain same. it should not change. then how can you say that the thickness is the factor in my case.??
Hi Ali, you are right : the thickness should be the same.
I did not say that the film thickness is the factor.
You deposited your material at different temperatures. Thus due to the elevated temperature your sample will show increased crystallinity. You have seen this by the decrease of peaks width with increasing temperature.
But when peak width decreases the peak height increases for the XRD peaks because the total/integral counts of an XRD peak are (in a wide range) independent on the degree of crystallinity.
It is not clear to me that the same number of pulses will lead to the same amount of deposited material. It is well known that when one starts with a fresh target surface the deposition rate is very high compared to a used target of the same material. The particles ejected from a fresh surface are also significantly lower. So unless this target has been used pretty consistently and the surface has reached a steady state morphology the deposition rate and final thickness may not be the same for each run.
Thanks James Greer .. its a one good reason But if we are taking large number of laser pulses around 40K , then how much it could effect the rate of ablation. ... it will become the same at the end.
My experience with PLD is mostly with large targets and large area PLD. The smallest targets we typically use are 2" OD. We always find that the deposition rate for a new target (or target that has been repoloished) starts out high and drops off. The deposition rate then drops in an exponential way to some steady state value. The time to reach the steady state value depends on target size, spot size, fluence, and total number of pulses as well as target material. If you use small 1" targets you also typically end up with having to resurface the target very often which is an expensive thing to do with Pt. If you don't resurface the target the 1" target will usually form a trench and the plume direction will change as the gross morphology of the target changes - not the surface of the target. All this must be taken into account when you want to grow multiple films with small targets of the same thickness and quality.
Thanks alot James , you have a reasonable justification. I used 1" diameter target with thickness around 0.01" . 6.6 gm weight.
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