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

Find the characteristic impedance, (a) Now consider a typical open-wire tra...

(a) Now consider a typical open-wire transmission line with parameters of R = 14 /mi, L = 4.6 mH/mi, C = 0.01 µF/mi, and G = 0.3×10 -6 S/mi. If the line operates at 1 kHz, find t

Compute efficiency of transformer in power factor lagging, Q. A 10-kVA, 200...

Q. A 10-kVA, 200:400-V, single-phase transformer gave these test results: • Open-circuit test (LVwinding supplied): 200V, 3.2 A, 450 W • Short-circuit test (HV winding suppli

Find the rotor copper loss, A three-phase, 50-hp, 440-V, 60-Hz, four-pole, ...

A three-phase, 50-hp, 440-V, 60-Hz, four-pole, wound-rotor inductionmotor operates at a slip of 0.03 at full load,with its slip rings short-circuited. The motor is capable of devel

What is use of co-processor in a typical microprocessor, What is use of co-...

What is use of co-processor in a typical microprocessor based system. This is a processor that works in parallel with the major processor. This has its own set of specialized i

Network analysis, expain how to do proper initial approximatio for the give...

expain how to do proper initial approximatio for the given cct....... by a example

Electromechanical and electronic switching system, Q. Compare electromechan...

Q. Compare electromechanical switching system with electronic switching system. Sr. No Electromechanical switching System Electroni

What do you mean by insurance, Q. What do you mean by Insurance? This i...

Q. What do you mean by Insurance? This is done by creating a common fund out of the contribution (known as premium) from several persons who are equally exposed to the same los

Calculate the v number and the number of guided modes, A multimode step ind...

A multimode step index fibre along with a core diameter of 80µm and a associative refractive index difference of 1.5% is operating at a wavelength of 0.85µm. If the core refractive

Explain and draw hysteresis loop for soft magnetic material, Draw the hyste...

Draw the hysteresis loop for a soft magnetic material and compare it with the hysteresis loop of hard magnetic material. Give two examples of each. Soft and hard magnetic mate

What is a co-processor, What is a co-processor? 8087 NDP (numerical da...

What is a co-processor? 8087 NDP (numerical data processor) is also termed as math co-processor that is used in parallel with the major processor for number crunching applicat

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