Metal–oxide–semiconductor structure, Electrical Engineering

Metal-Oxide-Semiconductor Structure

A traditional metal-oxide-semiconductor abbreviated as MOS structure is acquired by growing a layer of silicon dioxide (SiO2) on top of a silicon substrate and depositing a layer of metal or polycrystalline silicon (the latter is typically used). Since the silicon dioxide is a dielectric material, its structure is equal to a planar capacitor, along with one of the electrodes replaced by a semiconductor.

While a voltage is applied across a MOS structure, it changes the distribution of charges in the semiconductor. If we refer a P-type semiconductor (along with NA the density of acceptors, p the density of holes; p = NA in neutral bulk), a positive (+ive) voltage, VGB, from gate to body (see figure) forms a depletion layer by forcing the positively charged holes away from the gate-insulator or semiconductor interface, leaving exposed a carrier-free region of immobile, negatively charged acceptor ion. If VGB is sufficiently high, a high concentration of negative charge carriers forms in an inversion layer situated in a thin layer next to the interface in between the semiconductor and the insulator. Not like the MOSFET, in which the inversion layer electrons are supplied fast from the source or drain electrodes, in the MOS capacitor they are generated much more slowly by thermal generation by carrier generation and recombination centers in the depletion region.

145_Metal–oxide–semiconductor structure.png

                                      Figure: MOSFET structure and channel formation

Usually, the gate voltage at which the volume density of electrons in the inversion layer is similar as the volume density of holes in the body is called the threshold voltage. This structure along with p-type body is the basis of the N-type MOSFET that needs the addition of an N-type source and drain regions.

Posted Date: 1/11/2013 1:13:56 AM | Location : United States







Related Discussions:- Metal–oxide–semiconductor structure, Assignment Help, Ask Question on Metal–oxide–semiconductor structure, Get Answer, Expert's Help, Metal–oxide–semiconductor structure Discussions

Write discussion on Metal–oxide–semiconductor structure
Your posts are moderated
Related Questions
Explain Bimetals. Bimetals : It is made of two metallic strips of not like metal alloys with various coefficients of thermal expansion. At a specific temperature the strip wil

Q. A 100-kW, 230-V, dc shunt generator, with R a = 0.05 , and R f = 57.5  has no-load rotational loss (friction, windage, and core loss) of 1.8 kW. Compute: (a) The generato

Q. Illustrate procedure of Hex to Binary Conversion? It is also simple to convert from an integer hex number to binary. This is achieved by: Convert the Hex number t

Digital Systems 1. Describe the working of Binary comparator (Magnitude comparator) a. Define Binary comparator b. Binary comparator working process with logical diagrams 2.

Q. Explain the three-line cable Residential wiring? The three-line cable coming out of the secondaries of the distribution transformer on the utility pole passes through the el

Consider the RL circuit of Figure with R = 2, L = 5H, and v(t) = V = 20 V (a dc voltage source). Find the expressions for the inductor current i L (t) and the inductor voltage v L

Considering the circuit shown in Figure (a), find the state of operation and operating point if the BJT has β = 80 and other typical values of a silicon BJT at room temperature.

Q.9 What are the main differences between VGA and CGA graphics adapters? Ans: Colour Graphics Adapter (CGA), initially also known as Colour/Graphics Adapter or IBM Colo

applications of heterodyne wave analyzer

Q. What do you mean by Dearness Allowance? Ans: Dearness Allowance is in the type of compensation for Established increase in the cost of living and comprised of Dearness All