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

General, a single phase 120 volts, 60hertz supply is connected to a coil of...

a single phase 120 volts, 60hertz supply is connected to a coil of 200 turns wound round a toroidal magnetic core with a mean length 100cm and cross section 20cm square &relative p

Develop an analog computer simulation diagram, Q. Develop an analog compute...

Q. Develop an analog computer simulation diagram to solve the differential equation with y(0) = 2 and ? y(0) = 0.

Discuss how wavelet transform is suitable, Q. Discuss how Wavelet Transform...

Q. Discuss how Wavelet Transform is suitable for each application below. You can give examples  if you need to. a) multi-resolution analysis of signals and images b) space-fr

FET, shockely equation?

shockely equation?

Estimate the change in hysteresis loss, (a) Estimate the hysteresis loss at...

(a) Estimate the hysteresis loss at 60 Hz for a toroidal (doughnut-shaped) core of 300-mm mean diameter and a square cross section of 50mmby 50mm. The symmetrical hysteresis loop f

Segment assembler directive, What do you understand by SEGMENT assemble...

What do you understand by SEGMENT assembler directive? SEGMENT: This directive explains to the assembler the start of a segment along with name segment-name. The segment

What is the function performed by sim instruction in 8085, What is  the fu...

What is  the function performed by SIM instruction in 8085? SIM -Set Interrupt Mask. This instruction masks the interrupts as desired .it also sends out serial data by the seri

Hysteresis results in a dissipation of energy, Hysteresis results in a diss...

Hysteresis results in a dissipation of energy Hysteresis results in a dissipation of energy which appears as a heating of the magnetic material. The energy loss associated wit

Operation of an integrating circuit, Q. What is the principle of operation ...

Q. What is the principle of operation of an integrating circuit? The RC integrator is typically a series RC circuit that uses the capacitor to develop its output. Since voltage

Explain the working of elecro static precipitator, With the help of neat an...

With the help of neat and clean diagram illustrate the working of Elecro Static Precipitator (ESP). Describe the following: (a) Coal Handling Systems (b) Coal Storage

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