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

Obtain an expression for the induced emf, Q. Consider a conducting loop of ...

Q. Consider a conducting loop of length l and width w, as shown in Figure, rotated about its axis (shown by the broken line) at a speed of ωm rad/s under the influence of a magneti

Calculate the voltage regulation, The per-phase synchronous reactance of a ...

The per-phase synchronous reactance of a three-phase, wye-connected, 2.5-MVA, 6.6-kV, 60-Hz turboalternator is 10. Neglect the armature resistance and saturation. Calculate the vo

Explain electric flux density, Electric flux density (D): Electric flux...

Electric flux density (D): Electric flux density is a measurement of electric flux that pass through a unit of plate's area with a coincide angle, that is an area of 1 meter 2

Video graphics array and colour graphics adapter, What are the differences ...

What are the differences between Colour Graphics Adapter and Video Graphics Array graphics adapters? The Colour Graphics Adapter (CGA), originally also termed as the Colour/G

Ive some applications of hall effect, Give some applications of Hall Effect...

Give some applications of Hall Effect. Applications of Hall Effect: 1. This is used for finding whether a semi-conductor is N-type or P-type. 2. This is used in finding

Explain by using a circuit diagram a darlington pair, Q. Explain by using a...

Q. Explain by using a circuit diagram, a ‘Darlington Pair'. Mention its advantages? THE DARLINGTON PAIR : This is a very special way of direct coupling of two transistors. The

Radio hardware, Filters 1. You need to design a lowpass filter with cutoff ...

Filters 1. You need to design a lowpass filter with cutoff frequency Fc= 1MHz. a. What is the minimum filter order required for 30 dB rejection (-30 dB gain) of 10 MHz? b. What is

Find the turns ratio of the ideal transformer, Q. Consider an amplifier as ...

Q. Consider an amplifier as a voltage source with an internal resistance of 72 . Find the turns ratio of the ideal transformer such that maximum power is delivered when the amplif

Show the amenability to computer processing, Q. Show the Amenability to com...

Q. Show the Amenability to computer processing? Due to the digital data collected and stored in the form of a matrix, the same becomes amenable to processing on computers. By f

What is the difference between a tem mode and a te mode, Q. (a) What is the...

Q. (a) What is the difference between a TEM mode and a TE mode? (b) Explain the terms "cutoff wavelength" and "dominant mode" as applied to waveguides. Find the cutoff wavelengt

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