I prepare porous silicon with conditions used before with the same properties of silicon substrate, but usually i get pore diameter lower than the one previously obtained. Could anyone tell me what is the problem?
Thanks for attention.
The reproducibility of porous silica (aluminosilica) is not a simple problem. Every little detail could affect on synthesis like 3-5 оС overheat, more rapid mixing of reagents and so on. I recommend you to show the exact paper (synthesis) you followed.
Hi Evgeny Naranov
Thanks for the reply, you can find the followed paper here.
If all the parameters are fixed like concentration of electrolyte, current density, silicon resistivity etc then i would suggest check the temperature of solution. Also, the thickness of the ohmic contact could have an effect. If it is n-type, then backside illumination could have an effect on the pore size. Hope this helps.
Thank you very much for your reply Sivakumar, it is really helpful.
Please, could you give me more explanation about the effect of the thickness of the ohmic contact. It is Al and the authers in the followed paper did not mention the value of its thickness. is it better to use small thickness to get larger pore diameter to avoid the illumination of the backside?
In the attached picture you can find the structure of the holder of the silicon sample. Do you think the backside cause any illumination, although it is hidden?
if you are using p-type silicon, you don't require backside illumination as there are electronic holes in p-type silicon. when you mentioned about the conditions were all same, i was wondering about the effect of ohmic contact. you could try with different thickness of Al and check the results. just a suggestion.
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