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Field Effect Transistors

by Editor1 last modified March 07, 2007 - 11:31

In the 1970s, to reduce manufacturing costs and increase integration capability, industry moved away from bipolar [transistors] and toward metal-oxide-semiconductor field effect transistor (MOSFET) structures.


PHOTO with the above

For MOSFET device operation, voltage applied to the gate electrode produces an electric field in the semiconductor, attracting charge to the silicon/dielectric interface. 

A separate voltage applied between the source and drain then enables current to flow to the drain in a direction perpendicular to the applied gate field. Device geometry is determined by the need for the field in the channel to be determined primarily by the gate voltage and not by the voltage between the source and drain. In this structure, current flow to or from the gate electrode is limited by leakage through the gate dielectric.

MOS devices can be either NMOS or PMOS, depending on the channel doping type (p- or n-type, respectively) and the charge type (electrons or holes, respectively) flowing in the inversion layer channel. Pairing of individual NMOS and PMOS transistors results in a complementary MOS (CMOS) circuit.

            Handbook of Nanoscience, Engineering, & Technology
            Gregory N. Parsons
 


Chapter 2: Nanotechnologies
LOGIC DESIGN OF NANO ICs
Svetlana N. Yanushkevich, Vlad P. Shmerko and Sergey Edward Lyshevski

There are fundamental and technological differences between nanoelectronic devices versus microelectronic (even possibly nanometers in size) devices, e.g., nanoICs vs. integrated circuits (ICs). Even though field-effect transistors can possibly reach 100 nm dimensions for a complete microdevice, they still cannot be called nanoelectronic devices. Novel physics, integrated with design methods and nanotechnology, leads to far-reaching revolutionary progress. For example, multiterminal 1 × 1 × 1 nm electronic nanodevices (endohedral fullerenes, doped fullerenes, functional carbon molecules, etc.) are not submicron microelectronic devices.