I have purchased 20x25cm gold sputter coated PET sheets from a commercial supplier. The thickness of gold layer is 10-20nm thickness and it is very smooth by AFM. The resistance of the sheets across of the diagonal corner is ~35 to 40 Ohms. I have produced 1mm and 2mm width tracks of varying lengths from 25mm to 100mm by laser ablation method. All of them showed infinite resistance (> Mega Ohms). For comparison, I have prepared few lines of (roughly)1 and 2mm width and lengths from 25mm to 200mm using scalpel. All of them showed very good conductance.
I am looking for your suggestions, why gold microstructures prepared by laser ablation method shows very high resistance?
Have you tried to check the structure after ablation? thin gold layers tend, at heating, to coagulate into small islands, and naturally such system does not conduct well.
I retain the hope that the article will help find the answer. All our experts in this area of expertise are now available vacation.
What is the pulse duration of your laser? With nanosecond pulsed lasers gold melts around the spot, in your case substrate too. This may lead to mechanical stresses and correspondingly delamination and/or fractures of gold film. There is also a sound wave. One will probably need at least picosecond or maybe even femtosecond pulsed lasers to alleviate these problems. Playing with pulse energy and repetition may also help.
Agree with Shavkat that you may need to optimize the laser parameters but the pulse duration is not necessary the limit, with the local power density regulated by external focusing usually being the primary control. Nanocrystalline gold.will show higher resistivity than quoted for polycrystalline films. Annealing may also help if permitted by applications.
Have you tried to check the structure after ablation? thin gold layers tend, at heating, to coagulate into small islands, and naturally such system does not conduct well.
Thank you Dr Yuri Paskover.
Observed the track by optical microscope. Didn't find any noticeable change.
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