Solid State Electronic Devices, 7th Edition

5.7 Metal–Semiconductor Junctions

Many of the useful properties of a p-n junction can be achieved by simply forming an appropriate metal–semiconductor contact. This approach is obviously attractive because of its simplicity of fabrication; also, as we shall see in this section, metal–semiconductor junctions are particularly useful when high-speed rectification is required. On the other hand, we also must be able to form nonrectifying (ohmic) contacts to semiconductors. Therefore, this section deals with both rectifying and ohmic contacts.

5.7.1 Schottky Barriers

In Section 2.2.1 we discussed the work function qΦ_m of a metal in a vacuum. An energy of qΦ_m is required to remove an electron at the Fermi level to the vacuum outside the metal. Typical ...