Intrinsic material, Electrical Engineering

Assignment Help:

Intrinsic Material

  1. A perfect semiconductor crystal with no impurities or lattice defects.
  2. No carriers at 0 K, since the valence band is completely full and the conduction band is completely empty.
  3. For T > 0 K, electrons are thermally excited from the valence band to the conduction band (EHP generation).
  4. EHP generation takes place due to breaking of covalent bonds => required energy = Eg.
  5. The excited electron becomes free and leaves behind an empty state (hole).
  6. Since these carriers are created in pairs, the electron concentration (n/cm3) is always equal to the hole concentration (p/cm3), and each of these is commonly referred to as the intrinsic carrier concentration (ni).
  7. Thus, for intrinsic material n = p = ni.
  8. These carriers are not localized in the lattice; instead they spread out over several lattice spacings, and are given by quantum mechanical probability distributions.
  9. Note: ni = f (T).
  10. To maintain a steady-state carrier concentration, the carriers must also recombine at the same rate at which they are generated.
  11. Recombination occurs when an electron from the conduction band makes a transition (direct or indirect) to an empty state in the valence band, thus annihilating the pair.
  12. At equilibrium, ri =gi, where gi and ri are the generation and recombination rates respectively, and both of these are temperature dependent.
  13. gi(T) increases with temperature, and a new carrier concentration ni is established, such that the higher recombination rate ri(T) just balances generation.
  14. At any temperature, the rate of recombination is proportional to the equilibrium concentration of electrons and holes, and can be given by ri= αrn0p0 = αrni2=gi(5) where αris a constant of proportionality (depends on the mechanism by which recombination takes place).

Related Discussions:- Intrinsic material

Explain ferrites and its uses in high frequency devices, Explain ferrites a...

Explain ferrites and its uses in high frequency devices. A group of magnetic alloys show the property of magnetisation that change, with percentage of various constituent atoms

Calculate area of heating surface, Question: An evaporator is a device ...

Question: An evaporator is a device in which a feed stream is concentrated by boiling a solution. A combination of heating and reduced pressure are used to induce the boiling.

Assigment, what is p-n junction and how its work

what is p-n junction and how its work

Explain basic control systems, Q. Explain Basic Control Systems? Electr...

Q. Explain Basic Control Systems? Electric energy is widely used in practice, because of the ease with which the system and device performance can be reliably controlled. One o

Find the diameter of a circular waveguide, Q Find the diameter of a circula...

Q Find the diameter of a circular waveguide that will have a lower cutoff frequency of 10 GHz and also specify its largest usable frequency.

Determine the resistivity of the wire, The resistance of 1.5 km of wire of ...

The resistance of 1.5 km of wire of cross-sectional area 0.17 mm 2 is 150Ω. Determine the resistivity of the wire.

Research publication, i need research publication help. The topic is PHASED...

i need research publication help. The topic is PHASED ARRAY ANTENNA DESIGN for KU-band. I want a research paper that can be published in some conference.

Reversibility principle, The reversibility principle of electrical machines...

The reversibility principle of electrical machines states that an electrical machine can be used to operate either as a motor, converting electrical to mechanical energy, or as a g

Actual voltage reading in decimal, Prepare the assembly code to make a Digi...

Prepare the assembly code to make a Digital Volt Meter that shows the message and the correct voltage on the LCD. Once you managed to display the hex value for the conversion you w

Explain transfer of risk, Q. Explain Transfer of Risk? In case of this ...

Q. Explain Transfer of Risk? In case of this method, risk is transferred to some other person or organization. In other words, under this method, a person who is subject to ris

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd