In practice, even an engineer rather abstract physical concepts can make a big difference.For example, the electron work function of metal - a standard value for the developer of electronics systems.Of course, it requires more in-depth specialist knowledge, depending on the materials with which to work.This value is not only metals, but any solids, including semiconductors.If we consider a pair of two semiconductors, typically used Anderson.But if the said material is joined to the metal, it is generally useful to the Schottky-Mott.However, the calculations will be inaccurate, and the main role in this is to stabilize the Fermi energy levels.
definition
In physics, solid work function - the minimum thermodynamic effect (it is the same energy) required to detach an electron from a solid and place in a point outside its surface.All generalized calculations made under the assumption that around the body - a vacuum.This point is far enough on the scale of atomic dimensions, but close enough to be under the influence of an electric field in a vacuum.The work function - it is not a characteristic of the material composition, but rather the quality of its surface.It is connected with the peculiarities of the crystal face and the degree of contamination.
theoretical formula
work function is numerically equal to the sum of the two energies.Firstly, the amount needed to remove an electron from an atom system.Secondly, the amount of energy required to place an electron in an atom is the surface of the solid.
Caution
Some physical phenomena are very sensitive to the numerical value of the indicator "work function".That formula, as discussed above, is used to construct the simplified theoretical models, not more.In the experiments, the values of this index can be quite different from the formula calculations obtained without experience.If the surface is not smooth, not homogenous, the exact value calculations themselves, to obtain the empirical data, it becomes almost impossible.
measurement methods Groups
electron work function is calculated by several methods, and based on completely different physical phenomena.Total distinguish between two groups of experimental methods.Absolute use of electron emission from the sample, provoked by photoemission, high temperature, or field release of tunneling electrons.Relative methods are used the contact potential difference between the test sample and the reference electrode.
It is difficult to predict the magnitude of the work function with a high accuracy without conducting a pilot study.But there are certain trends that scientists have found over the years with this phenomenon.Almost always less than the value of metals with an open lattice.For the stupid faces of the crystal is higher than for acute.The explanation of these phenomena are quite obvious.In an open lattice of the electron weaker, and at an acute angle of external influences on the atom are made easier.
