The correct answer is B. Polysilicon.
Polysilicon is a semiconductor material that is used as the gate material in nMOS devices. It is a thin film of silicon that is deposited on the surface of the substrate. The gate material is responsible for controlling the flow of current through the device.
Silicon is a semiconductor material that is used as the substrate in nMOS devices. It is a thin layer of silicon that is deposited on the surface of the wafer. The substrate is the foundation of the
device and provides the support for the other layers.Boron is a dopant that is used to create n-type regions in nMOS devices. It is a small amount
of boron that is added to the silicon substrate. The boron atoms replace some of the silicon atoms in the crystal lattice. This creates a region of the substrate that has a higher electron concentration than the surrounding region.Phosphorus is a dopant that is used to create p-type regions in nMOS devices. It is a small amount of phosphorus that is added to the silicon substrate. The phosphorus atoms replace some of the silicon atoms in the crystal lattice. This creates a region of the substrate that has a higher hole concentration than the surrounding region.
In conclusion, the correct answer is B. Polysilicon.