Surface charge
From Wikipedia, the free encyclopedia
Surface charges is the electric charge present at an interface, for instance on the surface of a semiconductor material, or for example, on the surface of a protein.
In semiconductors, surface charge originates from a disrupted lattice structure. The presence of surface charge also alters the distribution of charge in the near-surface region of the semiconductor. In conductors of uniform resistivity at equilibrium, there can be no free charges in the bulk, instead all the charge density is on the surface.
To measure the surface charge surface charge analyzers are utilized, although electrostatic fieldmeters or voltmeters can also be used.
The average surface charge density σ over an area A is calculated by the following formula:
where σ is the surface charge density and q is the amount of charge.
The measurement of surface charge density has applications in:
- Electrical engineering. Electrostatic potentials and fields for systems of conducting electrodes may be obtained from the surface charge density.
- Biology. Maturation of cytokine secretion in dentrific cells may be determined by their surface charge
