Dear Shivaram Arun,

You don`t need to roughen the surface to improve adhesion between the nanotubes and Al . But, you HEAT the substrate while Al deposition (100 to 200 C would be enough).

1) See if the swurface roughens by depositing the films at a higher

pressure. Normally thermall evaporation is done at 10-6 , try to

evaporate the film at 10-5 to 10-3 vacuum level quickly. You can first evacuate the chamber down to 10-6 Torr, and then back fill with argon to raise the pressure. There will be more scattering at higher pressures, and there is every chance that you can roughen the film.

2) you can try checking the roughness of the film using AFM (atomic force microscopy).

2) or alternately take an already roughened glass substrate. This can be done by ethching the glass by buffered HF (hydrofluoric acid.) and vary the etching time, you will get a roughened glass substrate. and then coat your aluminum film with should stick to it.

The roughened film has nothing to do with adhesion. How have you determined that there exists an adhesion issue? Is it because (a) you don't see many nanotubes following their growth, or (b) because they are easily removed due to some physical contact you are making? Or are you just drop-casting nanotubes onto a surface? It is difficult to answer you question without knowing what you are actually doing.

If it is really necessary to roughen the surface, it can be done by dipping in dilute aluminum etchant for few seconds. A standard etchant of Al contains 80wt% Phosphoric Acid, 5% Nitric Acid, 5% Acetic Acid, and 10% DI Water. Increase the water content in the etchant and dip for few seconds. But this is not a controllable process.

Thanks,

Jose