BY ITSELF, silicon is not an effective conductor. It does not leave its electrons free for smooth flow of information. To make it less rigid, impurities are introduced into a pure silicon chip. The impurities free an electron or two and make the element a better conductor. This is called doping
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/doped-and-deadly
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/down-earth
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/science-and-technology
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/nano-technology
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/united-states-america-us
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/computers