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

Handshaking receiver system, You should document each step of each iteratio...

You should document each step of each iteration of your design. 1. You should include the following items from your preparation. a. A state diagram of the handshaking receive

Name 5 different addressing modes, The five addressing modes are given belo...

The five addressing modes are given below: Immediate, Register, Direct, Implied addressing modes           Register indirect,

What are the features used mode 2 in 8255, What are the features used mode ...

What are the features used mode 2 in 8255? The single 8-bit port in-group A is available. 1. The 8-bit port is bi-directional and additionally a 5-bit control port is availa

Ac link chopper - power supplies , AC Link Chopper This copper  has two...

AC Link Chopper This copper  has two  stage conversion. First DC is converted into AC  by the  use of inverter. The  magnitude of AC voltage is  varied  by the  transformer and

Explain the working of asynchronous (ripple) counters, Explain the Working ...

Explain the Working of Asynchronous (Ripple) Counters? An external clock is connected to the clock input of the first flip-flop (FF0) only. Thus FF0 changes state at the falli

Explain basic working of transport layer, Q. Explain basic working of Trans...

Q. Explain basic working of Transport Layer? It is responsible for establishing a network independent communication path appropriate for the specific terminal equipments (for exa

Op-amp amplifier, A voltage signal generated by a sensor conditioning circu...

A voltage signal generated by a sensor conditioning circuit varies from -0.5V to +0.5V . The signal from the sensor is to be connected to the analog to digital  converter which onl

What is absolute permittivity, Absolute permittivity (ε):  Permittivity ...

Absolute permittivity (ε):  Permittivity is a capacitance or ability to kept energy of a capacitor.  A force was also generated, called as electric force and the symbol. It d

Find the change in energy received by the charge, Q Acharge of 0.1Cpasses t...

Q Acharge of 0.1Cpasses through an electric source of 6 V from its negative to its positive terminals. Find the change in energy received by the charge. Comment onwhether the charg

Dielectric heating - stepper motor , Dielectric Heating Dielectric  l...

Dielectric Heating Dielectric  losses  occur in  insulating materials. These are same  as hysteresis losses  in magnetic materials. When  an alternating  electric  field  is 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