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PMOS uses p-channel (+) metal-oxide-semiconductor field effect transistors (MOSFETs) to implement logic gates and other digital circuits. PMOS transistors operate by creating an inversion layer in an n-type transistor body. This inversion layer, called the p-channel, can conduct holes between p-type "source" and "drain" terminals.
In PMOS, the polarities are reversed. The mode can be determined by the sign of the threshold voltage (gate voltage relative to source voltage at the point where an inversion layer just forms in the channel): for an N-type FET, enhancement-mode devices have positive thresholds, and depletion-mode devices have negative thresholds; for a P-type ...
In NMOS-type devices, the zone beneath the gate oxide is a thin n-type inversion layer on the surface of the p-type semiconductor substrate. It is induced by the oxide electric field from the applied gate voltage V G. This is known as the inversion channel. It is the conduction channel that allows the electrons to flow from the source to the ...
The inversion layer confines the flow of minority carriers, increasing modulation and conductivity, although its electron transport depends on the gate's insulator or quality of oxide if used as an insulator, deposited above the inversion layer. Bardeen's patent as well as the concept of an inversion layer forms the basis of CMOS technology today.
This is known as inversion. The threshold voltage at which this conversion happens is one of the most important parameters in a MOSFET. In the case of a p-type MOSFET, bulk inversion happens when the intrinsic energy level at the surface becomes smaller than the Fermi level at the surface. This can be seen on a band diagram.
In semiconductor physics, the depletion region, also called depletion layer, depletion zone, junction region, space charge region, or space charge layer, is an insulating region within a conductive, doped semiconductor material where the mobile charge carriers have diffused away, or been forced away by an electric field. The only elements left ...
Basically the accumulation of the (+)ve charged Donor ions (N D) on the polysilicon enhances the Formation of the inversion channel and when V gs > V th an inversion layer is formed, which can be seen in the figure 1(b) where the inversion channel is formed of acceptor ions (N A) (minority carriers). [3]
In 1948, Bardeen and Brattain patented an insulated-gate transistor (IGFET) with an inversion layer. Their concept forms the basis of CMOS technology today. [16] In 1957 Frosch and Derick were able to manufacture PMOS and NMOS planar gates. [17] Later a team at Bell Labs demonstrated a working MOS with PMOS and NMOS gates. [18]