Metal Semiconductor Contacts: Ohmic and Rectifying

摘要

The characteristics of contacts between metals and semiconductors are discussed on their energy band diagrams. Depending upon the relative magnitudes of their work functions, ideally the contact can either be rectifying (Schottky barrier) or ohmic. The experimental methods of fabricating Schottky barrier diodes and contacts to semiconductors and their current voltage characteristics are given. Junction capacitance of the diode is found to decrease with the reverse bias on the diode and the experimental results for a typical GaAs diode are presented. Values of barrier heights for the diodes using different metals on Si and GaAs are tabulated alongwith the various methods of making ohmic contacts.