Customer Service Chat
Get quote & make Payment
Extrinsic material, Electrical Engineering
In addition to thermally generated carriers, it is possible to create carriers in the semiconductor by purposely introducing impurities into the crystal => doping.
Most common technique for varying the conductivity of semiconductors.
By doping, the crystal can be made to have predominantly electrons (n-type) or holes (p- type).
When a crystal is doped such that the equilibrium concentrations of electrons (n0) and holes (p0) are different from the intrinsic carrier concentration (ni), the material is said to be extrinsic.
Doping creates additional levels within the band gap.
In Si, column V elements of the periodic table (e.g., P, As, Sb) introduce energy levels very near (commonly 0.03-0.06 eV) the conduction band.
At 0 K, these levels are filled with electrons, and very little thermal energy (50 K to 100 K) is required for these electrons to get excited to the conduction band.
Since these levels donate electrons to the conduction band, they are referred to as the donor levels.
Thus, Si doped with donor impurities can have a significant number of electrons in the conduction band even when the temperature is not sufficiently high enough for the intrinsic carriers to dominate, i.e., n
=> n-type material, with electrons as majority carriers and holes as minority carriers.
In Si, column III elements of the periodic table (for example, B, Al, Ga, In) introduce energy levels very near (commonly 0.03-0.06 eV) the valence band.
At 0 K, these levels are empty, and very little thermal energy (50 K to 100 K) is required for electrons in the valence band to get excited to these levels, and leave behind holes in the valence band.
Since these levels accept electrons from the valence band, they are referred to as the acceptor levels.
Thus, Si doped with acceptor impurities can have a significant number of holes in the valence band even at a very low temperature, i.e., p
=>, p-type material, along with holes as majority carriers and electrons as minority carriers.
The extra electron for column V elements is loosely bound and it can be liberated very Easily => ionization; thus, it is free to participate in current conduction.
Similarly, column III elements create holes in the valence band, and they can also participate in current conduction.
Rough calculation of the ionization energy can be made based on the Bohr's model for H
atoms, considering the loosely bound electron orbiting around the tightly bound core electrons. Thus,
is the relative permittivity of Si.
Posted Date: 1/11/2013 4:44:09 AM | Location : United States
Ask an Expert
Extrinsic material, Assignment Help, Ask Question on Extrinsic material, Get Answer, Expert's Help, Extrinsic material Discussions
Write discussion on Extrinsic material
Your posts are moderated
Write your message here..
Diffrentiate between Brass and Bronze, Explain Brass and Bronze. Brass...
Explain Brass and Bronze. Brass - It is an alloy of copper and zinc with 60 percent copper and 40 percent zinc. Its electrical resistivity of Brass is 7.0 X 10 -8 ohm-m th
Control system., how does Proportional band affect the performance of contr...
how does Proportional band affect the performance of control system?
First generation 1946- 1654 - history of computer, First Generation (1946- ...
First Generation (1946- 1654) In the first generation computer vacuum tubes and valves were used. These computer were very large in size ( thousands of square feet on the fl
Read-and-write memory, Q. Read-and-write memory? Writing is the same as...
Q. Read-and-write memory? Writing is the same as storing data intomemory and reading is the same as retrieving the data later. RAM is said to be volatile because its contents a
Determine the flux, Q. Consider themagnetic circuit of Figure. Let the cros...
Q. Consider themagnetic circuit of Figure. Let the cross-sectional area AC of the core, be 16 cm 2 , the average length of the magnetic path in the core lC be 40 cm, the number
Explain microprocessor development system, Explain Microprocessor developme...
Explain Microprocessor development system. Microprocessor development system: Computer systems consist of undergone many changes lately. Machines which once filled large area
Wire-line and fiber-optic channel, Q. Wire-line and Fiber-optic channel? ...
Q. Wire-line and Fiber-optic channel? Wire-line channels are used extensively by the telephone network for voice, data, and video transmission. Twisted-pair wire lines (with
Determine the value of resistance, Determine the value of Resistance: ...
Determine the value of Resistance: Determine the value of R, so that the condition for resonance is fulfilled Figure Solution Admittance of first branch
Determine the equivalent impedance, Q. A 75-kVA, 230/115-V, 60-Hz transform...
Q. A 75-kVA, 230/115-V, 60-Hz transformer was tested with these results: • Open-circuit test: 115 V, 16.3 A, 750 W • Short-circuit test: 9.5 V, 326 A, 1200 W Determine:
#title.superposition theorem, .coments on the limitation of the superpositi...
.coments on the limitation of the superposition theorem
Accounting Assignment Help
Economics Assignment Help
Finance Assignment Help
Statistics Assignment Help
Physics Assignment Help
Chemistry Assignment Help
Math Assignment Help
Biology Assignment Help
English Assignment Help
Management Assignment Help
Engineering Assignment Help
Programming Assignment Help
Computer Science Assignment Help
Why Us ?
~24x7 hrs Support
~Quality of Work
~Time on Delivery
~Privacy of Work
Human Resource Management
Literature Review Writing Help
Follow Us |
T & C
Copyright by ExpertsMind IT Educational Pvt. Ltd.