Contact Fermi energy equilization

[Moreno]

When two dissimilar metals come into contact the Fermi energy equalizes. Electrons flow from metal with higher Fermi energy to the lower one. But then they create charge difference and electron flow stops. But what happens when two intrinsic (non-doped) semiconductors come in contact? If electrons and holes in these materials have the same mobility, will holes flow from one material to another as well?

[Enthalpy]

Hi Moreno,

 

the mobility plays no role here. It's just a matter of Fermi energy and of electron work function. And yes, you can expect some charge movement.

 

"Come in contact" is a source of complications, because surfaces and contacts are so imperfect that simple models with Fermi, work function, carrier densities give very wrong results. But with one single crystal, with different dopings or different but compatible semiconductors stacked by epitaxy, such models do apply - very well for silicon PN junctions, more or less for differing materials depending on the epitaxy quality.