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

Calculate the guage pressure, Questions: Part (a) A compressor inst...

Questions: Part (a) A compressor installed at a wharf (for loading container ships) is able to provide 6 bar.g pressure into the pressure receiver. The compressor is moved

Explain the construction and working of calomel electrode , 1.  Explain the...

1.  Explain the construction and working of Calomel electrode 2.  Derive an expression for the electrode potential of a glass electrode. 3.  What are ion selective electrodes

Obtain the value of rs, Consider and obtain the values for R S , R 2 , R 1 ...

Consider and obtain the values for R S , R 2 , R 1 , and R D . Apply the rule-of-thumb dc design procedure outlined in this section for a JFET with V P = 3V, I DSS = 20 mA, and a

Variable capacitors, how can I simulate air variable capacitors in cst simu...

how can I simulate air variable capacitors in cst simulator?

Show advantages and disadvantages of a r-c couple amplifier, Q. What are th...

Q. What are the advantages and disadvantages of a R-C coupled amplifier. Advantages · It has excellent frequency response. The gain is constant over the audio frequency ra

Explain about register marker, Q. Explain about Register marker? Regist...

Q. Explain about Register marker? Register marker: Stronger selectors perform searching and counting . Though, the crossbar switch has no ‘intelligence'. Something external to

Explain the alphanumeric coding - bcd to decimal conversion, Explain the Al...

Explain the Alphanumeric Coding - bcd to decimal conversion? For the inherently binary world of computer, it is necessary to put all symbols, letters, numbers, and so on into bin

Discuss the essentials of an oscillator, Q. Discuss the essentials of an os...

Q. Discuss the essentials of an oscillator? The essential components of an oscillator are (i) Tank Circuit: It consists of inductance coil(L) connected in parallel with ca

Use delta-wye transformation for network reduction, Use delta-wye transform...

Use delta-wye transformation for network reduction and determine the current through the 12- resistor in the circuit of Figure(a).

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