When it comes to electrical characteristics, solid matter falls into one of three categories: it is either a conductor, an insulator, or a semiconductor, depending on whether or how well it conducts electricity.
When p-type semiconductor and n-type semiconductor materials are placed in physical contact, the area around the contact (known as the junction) behaves differently than either of the two source materials.
The characteristic response of a solid state diode to an external electrical potential or to an energy source such as light forms the basis for devices such as bipolar junction transistors, solar cells, LEDs, lasers and photodiodes.
MOSFETs are planar surface devices that are the most commonly used variant of Field Effect Transistors (FETs);including Junction Gate Field Effect Transistors (JFETs) and Insulated Gate Field Effect Transistors (IGFETs).
It can be seen that all of the familiar components of a MOS device are present in the FinFET (drain, source, gate, gate dielectric) and that the device more effectively separates the source and drain from the substrate silicon.
Polysilicon thin films are produced using a process known as chemical vapor deposition or CVD. Heavily doped polysilicon and poly-silicide films have been used as gate electrodes and interconnects in MOS devices.