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

Combinational-sequential, Design combinational-sequential electronic logic ...

Design combinational-sequential electronic logic gate circuit for a car wash....

What are tightly coupled systems, What are tightly coupled systems or close...

What are tightly coupled systems or closely coupled systems? In a tightly coupled systems the microprocessor (either coprocessor or independent processors) might be share a com

Illustration of embedded web technology, Illustration of embedded web techn...

Illustration of embedded web technology An oven comprise an embedded processor. Owner can use a web ready mobile phone anywhere to control the oven remotely. By accessing a

Sr flip-flop, SR FLIP-FLOP (SRFF) The symbol for the SRFF is shown in F...

SR FLIP-FLOP (SRFF) The symbol for the SRFF is shown in Figure (a), in which S stands for "set," R stands for "reset" on the input side, and there are two outputs, the normal o

Explain the operation of the counter, Q. Figure shows the mod-8 counter whi...

Q. Figure shows the mod-8 counter which counts from 010 to 710 before resetting. Explain the operation of the counter and sketch the timing diagram.

Junctions and diodes, An intrinsic semiconductor at room temperature has fr...

An intrinsic semiconductor at room temperature has free electrons

What do you mean by pipelining in an 8086 processor, What do you mean by pi...

What do you mean by pipelining in an 8086 processor? The computer is composed of two kinds that operate  asynchronously single part called a BIU in the 8086,fetches instruction

Diode, #quetunnel diode stion..

#quetunnel diode stion..

Evaluate the transfer function, Since dc motors of various types are used e...

Since dc motors of various types are used extensively in control systems, it is essential for analytical purposes that we establish a mathematical model for the dc motor. Let us co

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