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

Solar energy, can i use the direct solar energy from solar plate to charge ...

can i use the direct solar energy from solar plate to charge my laptop without a battery

Ramp type dvm, use of ranging and attenuator circuit

use of ranging and attenuator circuit

Compute the number of electrons that pass a given point, Q A wire with n = ...

Q A wire with n = 10 30 electrons/m 3 has an area of cross section A = 1mm 2 and carries a current i = 50 mA. Compute the number of electrons that pass a given point in 1 s, and

What do you mean by internal data bus, What do you mean by internal data bu...

What do you mean by internal data bus? Internal Data Bus: A bus which operates only in the internal circuitry of the CPU, communicating between the internal caches of memory

Common-base configuration, Common-base configuration:  The common-bas...

Common-base configuration:  The common-base that is abbreviated as CB transistor configuration, which is as well termed as the 'grounded base' configuration, is displayed in

Program description , Program Description In the above  program  any t...

Program Description In the above  program  any two  numbers can be stored in register A and B ( by  replacing XX  and YY). Contents  of B are  compared with A. If  B CY = 0

3phase unbalanced load flow, under three phase 4 wire load unbalanced distr...

under three phase 4 wire load unbalanced distribution network how to calacualte the voltage across the load when no load resistance is specified, however the real and reactive powe

Obtain the time domain functions, Let ω = 2π × 60 rad/s corresponding to a ...

Let ω = 2π × 60 rad/s corresponding to a frequency of 60 Hz. (a) Consider v(t) = 100 √2 cos(ωt + 30°) V and i(t) = 10 √2 sin(ωt + 30°) A. Find the corresponding phasors ¯V and ¯

Inductor, What will I write in Inductor conclusion

What will I write in Inductor conclusion

What is meant by blanking, a. Explain the following terms: (6) (i) Persi...

a. Explain the following terms: (6) (i) Persistence of vision (ii) Flicker in motion pictures b. What is meant by blanking? What is the need of blanking pulses? Compare th

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