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Semiconductor

A semiconductor is a material which has electrical conductivity between that of a metal and an insulator. Semiconductors have a number of unique properties. They can change the conductivity by the addition of impurities (doping) or by the application of electric fields or light. This ability makes semiconductors very useful for devices that amplify, switch or convert electrical energy. The study of semiconductors and their properties relies on quantum physics to explain the motion of electrons inside a lattice of atoms.

Semiconductors are the foundation of modern solid state electronics. This includes radios, computers and telephones. Semiconductor-based electronic components include transistors, solar cells, light-emitting diodes and digital and analog integrated circuits. The increase in understanding of semiconductor materials has allowed the continuing increase in the complexity and speed of semiconductor devices.

A pure semiconductor is a poor electrical conductor as a consequence of having just the right number of electrons to completely fill its valence bonds. Through different techniques, the semiconductor can be modified to have excess of electrons or a deficiency of electrons. In both cases the semiconductor will become more conductive.

When the semiconductors are doped they join to metals, different semiconductors, and to the same semiconductor with different doping. The result of this junction often strips the electron excess or deficiency out from the semiconductor near the junction. The depletion region is rectifying and used to further shape electrical currents in semiconductor devices.

Electrons can be excited across the energy band gap of a semiconductor by various methods. These electrons carry their excess energy over a distance before dissipating their energy into heat. This effect is essential to the operation of bipolar junction transistors.

Electrons in semiconductors will absorb light and retain the energy from the light for a long enough time to be useful for producing electrical work instead of heat. This effect is used in the photovoltaic cell. Semiconductors can use thermoelectric generators to convert temperature differences into electrical power and vice versa. Peltier coolers use semiconductors for this reason.

Analysis of unbiased PN junction and physics

see attachment please please, please, please I need help to solve this Q I solved parts a,b, and c still need help in other parts the reference book I am using ( the physics of solar cell (nelson) ) Ch6 Here is some website can help http://ecee.colorado.edu/~bart/book/book/chapter4/ch4_3.htm http://my.ece.msstat

Estimate of power output of crystalline Si Boule photovoltaic

You have a 150 mm diameter boule of Si that is 1 meter long. What is the electrical power output you might expect to achieve if this material were made into solar cells - explain all assumptions. Most silicon monocrystals are grown by the Czochralski process into ingots of up to 2 meters in length and weighing several hundred

Plot of the Fermi distribution function for different temperatures

plot the fermi distribution function at 200,300 and 400k(all on grah) and discuss the results in comparison to question 4. http://lyle.smu.edu/ee/smuphotonics/Gain/CoursePresentationFall03/CarrierConcentration_0822.pdf http://ecee.colorado.edu/~bart/book/distrib.htm (2.4.3) these webs may help to plot the Fermi Function

Calculating Conductivity in Compound Semiconductor

Please explain to me how to solve part (b) of the following question Suppose 2.490 kg of Ga are combined with 2.510 kg As to produce 5.000 kg GaAs. (a) Will this produce a p-type or an n-type semiconductor? (b) Calculate the number of extrinsic charge carriers per cubic cm using a lattice constant a0 = 0.563 nm. (c) Calcul

Evaluating Conductivity of Doped Semionductors

A piece of Si is doped with Phosphorus to 1x1018 [1/cm3] Please calculate: (a) the electron concentration? (b) the hole concentration? (c) he conductivity of this piece of Si (d) Assume the thickness of the Si is 0.5µm, what is the Sheet Resistance (e) If the thickness of the Si is still 0:5µm, R1 with 1µm wide and 4µ

Nanotechnology - chiral vector

** Please see attached files for the complete problem description ** On the array of carbon atoms in figure 1, there is shown a chiral vector B and two unit vectors a_1 and a_2 (i) If the equation used to construct this chiral vector is B = na_1 + ma_2, state the values of n and m. (ii) State the chiral angle of the resul

Energy Bands for Continuous Distributions

Please provide explanations. 1. True or False: Energy bands represent continuous distributions of allowable electron energies in materials. 2. The electrical resistivity of copper is 1.68E-8 ï-m. Calculate the electrical current flowing through 20m of copper wire with an applied voltage of 120V. Assume the wire has a di

Depletion width of a pn junction

Depletion region is the layer formed between the p and n junction of a semi conductor diode due to the migration of charge carriers ie: electrons and holes across the junction, The charctereristics, ie the current-voltage relationship of a pn junction is very much depends on the width and properties of the depletion layer. The m

Physics: Batteries, Resistance and Current; Resistance in a Wire

Batteries, Resistance and Current Prelab: 1. What is the resistivity () of a resistor? What characteristics of a resistor affect the resistivity? Write a formula for this relationship, label each variable and indicate the units used to measure each. Would resistivity be constant for a specific resistor? 2.

Current Electricity: A rod with variable resistivity.

The resistivity of a semiconductor can be modified by adding different amounts of impurities. A rod of semiconducting material of length L and cross-sectional area A lies along the x-axis between x=0 and x=L. The material obeys Ohm's law, and its resistivity varies along the rod according to p(x)= p0exp(-x/L). The end of the rod

Semiconductor Light Detectors

A p-n photodiode acts as a photocell, the circuit is shown in this document. Outline the band profile of the diode for infinitely large RL for different levels of illumination.

Flatband and threshold voltages

An Al-silicon dioxide-silicon MOS capacitor has an oxide thickness of 450Angstroms and a doping of Na=10^15 cm^-3. The oxide charge density is Q'ss=3x10^11cm^-2. Calculate (a) the flat-band voltage and (b) the threshold voltage. Sketch the electric field through the structure at the onset of inversion.

Fixed Oxide Charge

Consider an aluminum gate-silicon dioxide p type silicon MOS structure with tox=450 angstroms. The silicon doping is Na=2x10^11cm^-3 and the flat-band voltage is Vfb=-1.0V. Determine the fixed oxide charge Q'ss.