Difference between revisions of "TF EIM Chapt3"

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The above images are suppose to represent the distribution of electrons in the crystal lattice cell.
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To understand this structure more let's consider the structure of a 1-D crystal of atoms
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A single free atom will have electrons bound to the atom due to the coulomb force.  The bound electrons are found in various energy levels.
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There are 14 different Bravais lattice configurations
 
There are 14 different Bravais lattice configurations
  

Revision as of 04:59, 15 February 2011

Semiconductor physics

There are 5 states of matter: Solid, liquid, gas, plasma (ionized gas) , and a Bose-Einstein condensate (quantum effects on a macroscopic scale).

Crystal Lattice

Semiconductor physics focuses on the solid state of matter in the form of crystals.

Crystals are formed when atoms are arranged in repeating structures called the crystal lattice. The recurrent structure which forms the crystal lattice is referred to a a cell.

Some popular cell names are


TF EIM SimpleCubic.jpeg TF EIM BodyCentereCubic.jpeg TF EIM FaceCentereCubic.jpeg
(SC) Simple Cubic (BCC) Body Centered Cubic (FCC) Face Centered Cubic

The above images are suppose to represent the distribution of electrons in the crystal lattice cell.


To understand this structure more let's consider the structure of a 1-D crystal of atoms


A single free atom will have electrons bound to the atom due to the coulomb force. The bound electrons are found in various energy levels.



There are 14 different Bravais lattice configurations

Crystal System Lattice type
Cubic Simple, Face Centered, Body Centered
Tetragonal Simple, Body Centered
Orthorhombic Simple, Face Centered, Body Centered, End Centered
Monoclinic Simple, End Centered
Rhombohedral Simple
Triclinic Simple
Hexagonal Simple

Most Semiconductors are made from Silicon and GaAs.


Silicon is a Face Centered Cubic cell

Silicon is an insulator if in pure form with 4 weakly bound (valence) electrons.

If you replace silicon atoms in the lattice with atoms that have either 3 valance or 5 valence electrons (doping) your can create sites with either a deficient number of electrons (a missing bond) or extra electrons (complete bond with a free electron)

TF EIM SiliconLattice np junction.jpg

By Doping silicon you can create sites with extra electrons (n-type) or sites with a deficient number of electrons (vacancies or holes ) (P-type)




Forest_Electronic_Instrumentation_and_Measurement