Correct Answer : Option (D) : Silicon dioxide
Explanation : A MOSFET is a field-effect transistor. It depends on the presence of an electric field to control the characteristics of the conductive channel. In the MOSFET, the gate is insulated from the substrate by a layer of silicon dioxide, which is basically glass. The charges accumulate on the gate to create the electric field instead of just having them flow out. So, while silicon is the main constituent of the conductive channel, a thin layer of silicon dioxide is used to insulate the gate.
