Specifically, I am working on the electrodeposition of semiconductors (CIGS films). At times, I end up getting poor adhesion between the thin-film and substrate. Use of complexing agents has been previously reported to improve adhesion. However, I want to avoid the use of complexing agents. Can somebody suggest a way to achieve good adhesion?
Hello,
It would be much easier to give you a precice answer if, you would share the information of what substarte and what semiconductormaterial you are using. But in general, a thin (5-10 nm) layer of Ti or Cr will increase the adhesion of most layers. As long as those materials are not interakting with you semiconductor i would just try those.
That's a very complex question without knowing the substrate and precursor chemicals. It could be a simple as micro-roughening your substrate, most likely with an acid dip. For that matter, ensuring that your substrate is free of unwanted oxy(hydr)oxide phases and other contaminants is very important. Especially if the adhesion problem isn't constant, with suggests surface contamination or variance in dissolved species. There are also methods of "pre-activating" substrates with an electrochemical potential/current poise or a sonicated dip in organic solvents.
Thank you Dr. Shawn. I am depositing CuInGaSe2 (CIGS) thin-films on Mo substrate. Do you know any precise idea for this system to improve adhesion. Thanks in advance.
Regards,
Sreekanth
Hi Sreekanth,
I don't have much experience with metallic Mo substrates, but if there's native oxide formation a good bet is a dilute HF dip. Other acids will work but HF will be the quickest way to dissolve native metal oxides. Concentrated acids are more likely to pit the metal, though that could also allow better deposit adhesion.
Sreekanth,
Cleaning is very important for refractory materials (e.g. Mo, W, Ni-Cr alloys) before deposition. A powerful acid mix for removing oxide scales is Nitric (50-70 vol%) and hydrofluoric (5-10 vol%) mix. It is commonly used to remove heat treat oxide scales on W and Ni-Cr, SS alloys. It will removal Mo oxide scales and provide rough surface for adherent CIGS deposition. Please check on composition from a reference book and beware of safety while working with this acid mix.
Thiru
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