ABSTRACT
The Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) is a device consisting of a channel with two reservoirs of mobile charges (i.e., free carriers with either negative or positive charge) at its ends. Both nMOSFETs and pMOSFETs are used and needed for complementary metal-oxide-semiconductor (CMOS) circuits. In the case of an enhancement pMOSFET, negative gate voltage has to be applied to make the channel conductive and turn on the device. The metal-oxide-semiconductor structure is the heart of the MOSFET. MOSFETs operated in the off-state under zero gate voltage are called enhancement or normally-off transistors. The great majority of commercial MOS circuits are still designed based on bulk MOSFETs. Silicon-on-Insulator MOSFETs constitute another important class of MOSFETs. While the technology of multiple-gate MOSFETs is more complicated compared to that of single-gate bulk and SOI MOSFETs, the multiple-gate devices do offer the advantage of improved scalability. Depending on the thickness of the Si body, SOI MOSFETs are categorized as partially depleted and fully depleted transistors.
