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..
What are the flags used in 8086, In 8086 Carry flag, Parity flag, Auxiliar...
In 8086 Carry flag, Parity flag, Auxiliary carry flag, Zero flag, Overflow flag, Trace flag, Direction flag Interrupt flag and Sign flag. Mainly there ae two types of int
Circuit used in window air conditioning, circuit used in window air condi...
circuit used in window air conditioning
Composition of mosfet, Composition of MOSFET In a test pattern the P...
Composition of MOSFET In a test pattern the Photomicrograph of two metal-gate MOSFETs. Probe pads for two gates and three source or drain nodes are entitled.Generally the se
Show that the force exerted on each charge, Q. Consider two 1-C charges sep...
Q. Consider two 1-C charges separated by 1 min free space. Show that the force exerted on each is about one million tons.
Security alarm system, In this Project you will simulate a Security Alarm s...
In this Project you will simulate a Security Alarm system using the Quick flash board. A switch is placed as shown in the figure below. The main goal of this project is: Task 1:
Drawing, #question what are the types of lines used there and their applica...
#question what are the types of lines used there and their application ..
Voltage regulator, voltage regulator using ic 741
voltage regulator using ic 741
Microprocessors, Memory location 2000H has the word 5000H stored in it. Wha...
Memory location 2000H has the word 5000H stored in it. What does each location contain after DEC WORD PTR [2000H].
Present and future trends in power systems, Q. Present and Future Trends in...
Q. Present and Future Trends in power systems? According to the Edison Electric Institute, electricity's share of U.S. primary energy was almost 36% in 1989, and it is likely t
Mathematics, The two sides of a triangle are 17 cm and 28 cm long, and the ...
The two sides of a triangle are 17 cm and 28 cm long, and the length of the median drawn to the third side is equal to 19.5 cm. Find the distance from an endpoint of this median to
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
Terms & Conditions
Copyright by ExpertsMind IT Educational Pvt. Ltd.