Silicon 2 : A chemical element (Si), atomic number 14, semi-metallic in nature, dark gray, that is an excellent semiconducting material and is the most common semiconducting material used in making photovoltaic devices
Young & Company Electric Power Products and Related Engineering Services, Glossary of Electrical Terms, http://www.youngco.com/young2.asp?ID=4&Type=3, CA., USA 2001. (Electr Sfty - Amer) {514}