# Is there a material that changes local conductivity

I hope this is the right forum to ask this question. Is there a material (preferably thin, like a membrane) that changes its local conductivity (by that I mean the permeability for an electric field; I hope it's the right term) upon excitation with light or heat? I have no idea where to start my search for something like that.

Thanks a lot.

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Any semiconductor will do this. –  John Rennie Apr 4 '13 at 7:19
Who would have thought that the answer is that easy. Just to make sure that I understand you correctly, I can have a sheet of semi-conducting material, locally shine a laser onto it and it will change its conductivity properties? –  fabee Apr 4 '13 at 7:41
–  John Rennie Apr 4 '13 at 8:43
Thanks a lot. Since I cannot accept your answer, I can at least upvote your comment. –  fabee Apr 4 '13 at 9:16
You should probably accept Manish's answer since he at least put in the effort to write one :-) Accepting an answer flags the question as "answered" otherwise it sits in the "Unanswered questions" queue forever. –  John Rennie Apr 4 '13 at 11:27