There are three related questions: 1] Consider the junction between two metals of differing work functions. The bands will need to bend to make the fermi-levels match and charge will transfer (in analogy to a metal-semiconductor junction). However, due to the density of charge carriers, there will be no "depletion zone" and no rectification, correct? Is there anyway to electronically notice this electric field at the junction? 2] A semimetal can be thought of as having both positive and negative charge carriers, and usually of low density, because of having a "negative" indirect gap. If we have a contact between a metal and semimetal of unequal work functions, can the bands be bent to cause a "depletion zone" for one charge carrier type, but not the other? Is there anyway to electronically notice this? 3] If the semimetal discussion above is correct, then can the junction be made p-type, and thus have n-p-n ... no current flow in either direction. This seems to suggest one could make a "field effect" like transistor out of just metals! Is there something wrong with this ideas? If not, then I assume it has already been tried. Does anyone know what it is called so I can read up on it? EDIT: By "electronically notice" I mean measurements done by including such a junction in an electronic circuit. Basically, I'm not interested in any "direct probe" type spectroscopic measurements.