ionized impurity scattering

In quantum mechanics, ionized impurity scattering is the scattering of charge carriers by ionization in the lattice. The most primitive models can be conceptually understood as a particle responding to unbalanced local charge that arises near a crystal impurity; similar to an electron encountering an electric field.{{cite web | url=http://www.superstrate.net/pv/mobility/impurity-scattering.html | title=Ionized impurity scattering | accessdate=September 26, 2011}} This effect is the mechanism by which doping decreases mobility.

In the current quantum mechanical picture of conductivity the ease with which electrons traverse a crystal lattice is dependent on the near perfectly regular spacing of ions in that lattice. Only when a lattice contains perfectly regular spacing can the ion-lattice interaction (scattering) lead to almost transparent behavior of the lattice. Impurity atoms in a crystal have an effect similar to thermal vibrations where conductivity has a direct relationship with temperature.

A crystal with impurities is less regular than a pure crystal, and a reduction in electron mean free paths occurs. Impure crystals have lower conductivity than pure crystals with less temperature sensitivity in that lattice.{{cite book

|author=Kip, Arthur F.

|title=Fundamentals of Electricity and Magnetism

|year=1969

|url=https://archive.org/details/fundamentalselec00kipa

|url-access=limited

|pages=[https://archive.org/details/fundamentalselec00kipa/page/n233 211]–213|publisher=McGraw-Hill

|isbn=0-07-034780-8}}