I have to repeat sputtering and flashing several times to see the herringbone reconstruction of gold surface in STM . I use E= 1keV and flashing at 500degC. Specially, if I load Au(111) in UHV after air exposure, cleaning is a many hours procedure. I donot anneal for long time after sputtering. Is there anyway to clean it in less time?
Alas, it's normal that it takes very long to get a really clean sample. That's the thing with UHV: you set up for hours for a 90 second experiment, then you set up for hours again.
But one thing might help: is your heater capable of going beyond 500°C? Of course you don't want to melt your sample, but going higher is definitely possible, maybe you can save one or two sweeps that way.
... and what is actually the sample: A thin film, a single crystal, and how is it prepared? If you employed polishing with diamond or SiC or alumina polishing paste, it might happen that your sample appears shiny and clean after heating, but the surface will entirely be made of Carbon (or Silicon or Alumina) - check the clean state with additional tools such as XPS, UPS, ... Good luck, Dirk
What Dirk Luetzenkirchen-Hecht said is a pretty valuable hint: maybe you're already doing it, but your first step should be a sputtering step, not an annealing step. If you start with the annealing, you may bake carbon impurities into the sample and the number of cycles you will require in order to get to an atomically clean surface will take much longer.
Hi Jurgen, Dirk and Artur,
My Au(111) substrate is single crystal. I first do sputtering and then flashing but not annealing.
Once I went beyond 600degC just for few minutes and then it created a hole in Au(111). So, I avoided annealing and just doing flashing(heating sample to 550deg for 2 minutes). But, I have to repeat these cycles several times. Does annealing in oxygen at 500deg or 600deg help?
Yeah, OK, my anneals back when I was using gold were also quite "flashy".
However, if 600°C cause a hole in the crystal, I would complain to the crystal manufacturer, that's definitely a temperature it should survive.
Hi Manischa,
maybe, I am naive and overlooking essentials of your work.
If your contaminant is airborne hydrocarbon stuff from the lab, you can combust it in some mild reactive plasma, mabe oxygen or air, in some few minutes. However, you need to do have some load lock from the plasma apparatus into your UHV system to avoid recontamination of your sample after the plasma process.
Best wishes,
Heinrich
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