Electrostatic charge vs. Electric current: Effect on electron density of states

[uby]

I am having difficulty ascertaining the difference between an electrostatic charge present on the surface of a conductor and the flow of an electron current (or holes, if you prefer) along the surface of a conductor with respect to their effects on the electron density of states (and, more specifically, the fermi level of the conductor). Let's assume that the conductor is a pure metal for sake of discussion.

When an electrostatic charge is present on the surface of the conductor, it is no longer electrically neutral. The conduction band will have extra electrons or be deficient of electrons, depending on the charge. Static charges naturally tend to be high voltage (though they are not required to be!). I would suspect that a negative charge would raise the fermi level while a positive charge would lower it.

On the other hand, a metal remains electrically neutral while a current run through it. Nevertheless, the potential difference applied across the metal will cause surface electrons to modify their energies, and, again, the fermi level should shift. However, I cannot easily distinguish this from the previous case.

Shouldn't the net electric charge have a notable effect on the electron density of states? Has there been any treatment of these effects in metals (not much interested in the behavior of semiconductors in this particular case) to which you can direct me for further reading?

Thanks!

 

[BigJDubs]

Yes, the net electric charge will affect the electron density of states, and this has been studied extensively in metals. In fact, when an electric current is passed through a metal, it can induce what is known as a "surface electric field" that alters the electron density of states near the surface of the metal. This effect is known as "electron accumulation," and it is usually studied using a technique called scanning tunneling microscopy (STM).In addition, the electric field generated by static charges can also induce a shift in the electron density of states near the surface of the metal. This effect is known as the "image force," and it is usually studied using a technique called angle-resolved photoemission spectroscopy (ARPES).Both of these effects can influence the Fermi level in the conductor, but their exact effects depend on the type of metal, the magnitude of the electric field, and other factors. For further reading, you may want to look up papers on electron accumulation, image force, and related phenomena in metals.