How to clean a ZnSe surface that contains an ultrahin layer (ca. 10 nm) of adsorbed organic material? 1. Polishing, sure, but it turns out that ZnSe is uncomfortably sticky, and the toxicity is also not so easy to handle in a polishing tool. 2. Solvents should be ideal, but they do not work (adhesion too strong). 3. Oxidation (in solution, or by plasma) removes the material, but also damages the ZnSe. Reduction would presumably remove Se and hence again damage the surface. 4. Any experience with other plasmas, e.g. argon? Or glow discharge? Ion milling/sputtering?
You may (first) try desorption of the organic contaminant from the zinc selenide surface by selecting some compatible solvent(s) of polarity close to what might be that of the adsorbed organic contaminant, being preferably also a suitable extractant for such kind of organics. Solvents such as acetone, isopropanol, hexane, diethyl ether, or chloroform; can be considered. You may gently swab the contaminated surface with a polishing microfiber cloth impregnated with the selected solvent(s). If that fails, you may still try warm water and soap.
If you think that etch-polishing is still required; you may consider alkalinized potassium ferricyanide aq. sol.: K3Fe(CN)6 (≤ 30 g) + KOH (0.57 g) + H2O (100 cm3); 1―2 min at room temperature.
Hello Alexander,
I would try to use a sticky tape to get a clean surface. Certain van der Waals planes can be splitted by this method. You fix a tape on the surface and pull it off.
To avoid atmospheric contamination you fix a lever on the surface and pull off in vacuum.
With regard
R. Mitdank
?? ZnSe can IMHO not be a vdW compound. It has (usually?!) wurtzite or zincblende structure, and is thus based on cubic and hex dense packaging. Can they be cleaved? The interactions between the densely packed layers are ionic and partially covalent, no?
I then assume that cleavage with a sticky tape is not possible. You must try it. But cleavage using a tool could be possible. This gives then clean surfaces.
R. Mitdank
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