"Semiconductors transmit electronic information. Gate dielectrics are insulators for this electron transmission, and as Professor Ma explains, "the insulator is like a wall upon which electrons are thrown, some electrons will seep through if the wall is too thin." The task for Professor Ma was to strengthen the silicon dioxide gate dielectric with minimum quantities of nitrogen, allowing information to be most efficiently transmitted, without electrons leaking in the process."
"Think of water flowing through a pipe, an insulator is like a pipe that's frozen: electrons can't get through. Semiconductors are materials that change from free-flowing conductor to a frozen insulator and back again, simply by zapping them with an electric current."
A very good link this is....