Semiconductors and Superconductors Ashley Heady 510 Advanced Inorganic

Band Theory  What happens when 2 atoms combine?  Huheey, James E., Keiter, Ellen A., and Kieter, Richard L., Inorganic Chemistry: Principles of Structure and Reactivity. 4th ed. Harper Collins: NY, pg

Band Theory  What happens when 8 atoms combine?  Huheey, James E., Keiter, Ellen A., and Kieter, Richard L., Inorganic Chemistry: Principles of Structure and Reactivity. 4th ed. Harper Collins: NY, pg

Band Theory  What happens when a mole of metal atoms combine?  Huheey, James E., Keiter, Ellen A., and Kieter, Richard L., Inorganic Chemistry: Principles of Structure and Reactivity. 4th ed. Harper Collins: NY, pg

Band Theory  When the number of atoms is large, the orbitals and energy levels will be close.  This forms a band of orbitals.  Show figure of a band with labeled valence band and conductance band and fermi level.

Band Theory  Monovalent metals  Divalent metals  Semiconductors  Insulators  Miessler, Gary L. and Tarr, Donald A., Inorganic Chemistry. 3rd ed. Prentice Hall: New Jersey, pg  White, Mary Anne., Properties of Materials. 1st ed. Oxford: New York: NY, 1999.

Band Theory  Density of State is the concentration of energy levels within bands.  Miessler, Gary L. and Tarr, Donald A., Inorganic Chemistry. 3rd ed. Prentice Hall: New Jersey, pg

Semiconductors  Two Types  Pure Intrinsic  Si or Ge  Doped  n-type  p-type

Intrinsic Semiconductors  Pure metal semiconductors  Miessler, Gary L. and Tarr, Donald A., Inorganic Chemistry. 3rd ed. Prentice Hall: New Jersey, pg

Doped Semiconductors  n-type  If the added material has more electrons in the valence shell than the host material.  n is for negative, adding electrons.  White, Mary Anne., Properties of Materials. 1st ed. Oxford: New York: NY, 1999.

Doped Semiconductors Each figure is showing more electrons in the host material and a promotion into conductance band of n-type.  Miessler, Gary L. and Tarr, Donald A., Inorganic Chemistry. 3rd ed. Prentice Hall: New Jersey, pg  White, Mary Anne., Properties of Materials. 1st ed. Oxford: New York: NY, 1999.

Doped Semiconductors  p-typed  If the added material has fewer valence electrons than the host.  Results in a positive hole.  White, Mary Anne., Properties of Materials. 1st ed. Oxford: New York: NY, 1999.

Doped Semiconductors Band diagrams for a p-type showing positive hole and accepting level  Miessler, Gary L. and Tarr, Donald A., Inorganic Chemistry. 3rd ed. Prentice Hall: New Jersey, pg  White, Mary Anne., Properties of Materials. 1st ed. Oxford: New York: NY, 1999.

 Huheey, James E., Keiter, Ellen A., and Kieter, Richard L., Inorganic Chemistry: Principles of Structure and Reactivity. 4th ed. Harper Collins: NY, pg

Superconductors  Superconductivity was discovered in  Mercury Metal was first used  At temperatures below 4.2K the resistance of Hg drops to zero.  Two types  Low temperature  High temperature

Low Temperature Superconductors  Type I  Meissner Effect  The property of expelling all magnetic flux when cooled below the critical temperature.  Miessler, Gary L. and Tarr, Donald A., Inorganic Chemistry. 3rd ed. Prentice Hall: New Jersey, pg

High Temperature Superconductors  Type II  Superconductor  Miessler, Gary L. and Tarr, Donald A., Inorganic Chemistry. 3rd ed. Prentice Hall: New Jersey, pg

References  Huheey, James E., Keiter, Ellen A., and Kieter, Richard L., Inorganic Chemistry: Principles of Structure and Reactivity. 4 th ed. Harper Collins: NY, pg  Miessler, Gary L. and Tarr, Donald A., Inorganic Chemistry. 3 rd ed. Prentice Hall: New Jersey, pg  White, Mary Anne., Properties of Materials. 1 st ed. Oxford: New York: NY, 1999.