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

Determine the line-to-line voltage at the load terminal, Q. A balanced delt...

Q. A balanced delta-connected load has a per-phase impedance of 45 60° . It is connected to a three-phase, 208-V, 60-Hz supply by a three- phase feeder that has a per-phase impeda

Determine the upper limit of tdm signal, A TDM signal of the type is formed...

A TDM signal of the type is formed by samplingM voice signals at fs = 8 kHz. If the TDM signal then modulates the amplitude of a 4-MHz carrier for radio transmission, determine the

Determine the nyquist sampling interval - radar system, Consider an S band ...

Consider an S band (3 GHz) radar with a rotating aperture antenna with a width of 3 m.  Suppose the antenna rotates at a rate of one rotation every 10 seconds.  Assume the 3 dB bea

Microcontroller, What are usue and all the details of 8051 microcontroller ...

What are usue and all the details of 8051 microcontroller with its block diagram pin diagram and all other details

Single sinusoid, Power up the "TIMS" unit by using the switch at the back. ...

Power up the "TIMS" unit by using the switch at the back. Connect the Pico Virtual Instrument (PicoScope) to the PC as per Appendix 1 On the "TIMS" unit, connect the 2 kHz (s

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

Blind equalization using constant modulus approach, please i need to prepar...

please i need to prepare thesis proposal based on the title above. analysis of recently exixting algorithm and propose an improved one. UGENTLY!!

3rd year electrical/electronics project, I`m a 3rd year electrical engineer...

I`m a 3rd year electrical engineering student studying in Canada, and there is a new course they added in my university for 3rd year students called Engineering Project. from the

Draw the differentiator circuit, Q. Draw the differentiator circuit. Explai...

Q. Draw the differentiator circuit. Explain its principle of operation with necessary waveforms ? A circuit in which the output voltage is directly proportional to the derivati

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