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

Dc machine, why very high resistance wire is used is field windind and low ...

why very high resistance wire is used is field windind and low resistance wire is used in armature winding in DC shunt machine?

Electronics circuits 1, Explain and drive the expression for fixed bias and...

Explain and drive the expression for fixed bias and potential divider.

ADC and DAC design, I''m trying to design ADC using MAX1198 and DAC using I...

I''m trying to design ADC using MAX1198 and DAC using IDAC in Multisim 12 but none of them are working. I need some help in this regard

Transformer, how back emf is produced in transformer?

how back emf is produced in transformer?

Explain internal data bus, Q. Explain Internal Data Bus? Internal Data ...

Q. Explain Internal Data Bus? Internal Data Bus: A bus which operates only within internal circuitry of the CPU, communicating among internal caches of memory which are part of

Pnp bipolar junction transistor, PNP The other kind of BJT is the PNP ...

PNP The other kind of BJT is the PNP with the letters "P" and "N" standing for the majority charge carriers inside the dissimilar regions of the transistor. Figure:

Explain about synchronous machines, Q. Explain about Synchronous machines? ...

Q. Explain about Synchronous machines? Large ac power networks operating at a constant frequency of 60 Hz in the United States (50 Hz in Europe) rely almost exclusively on sync

Characteristics of stepper motors - stepper motor , Characteristics of Ste...

Characteristics of Stepper Motors The main  characteristic of stepper  motors is torque  versus stepping or  pulse  rate. It give the  variation  of torque as a function of pu

Potentiometer, how can yuo calculate voltage,curent basing on the meter bri...

how can yuo calculate voltage,curent basing on the meter bridge?

What are the performance measures of oscillator circuits, Q. What are the p...

Q. What are the performance measures of oscillator circuits? 1. Stability: This is determined by the passive components. R, C and L determine frequency of oscillations. If R ch

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