Ohmic Contracts to Gallium Aluminum Arsenide for High Temperature Applications.
Annual technical rept. 1 Jul 85-30 Jun 86,
ROCKWELL INTERNATIONAL THOUSAND OAKS CA SCIENCE CENTER
Pagination or Media Count:
A method of modifying the Gallium Arsenides 100 interface Fermi level position EF has been investigated. For tunnel ohmic contacts the contact resistance depends exponentially on the energy difference between the conduction band minimum and EF thus, stable contacts with small values of this energy difference large values of EF could be important in designing nonalloyed ohmic contacts. Very thin approx. 10A epitaxial layers of Gallium that incorporate Arsenic have been found to produce exceptionally large values of EF, 1.0-1.2 eV relative to the valence band maximum as determined by x-ray photoelectron spectroscopy. Thick model contacts that include layered structures of Au, Ge, and Ni in various combinations have been used to establish conditions under which these large EF values can be preserved as determined by current-voltage measurements. The results question the usual assumption of a near mid-gap EiF position for the widely used alloyed AuGeNi ohmic contact and offer an alternative explanation for the mechanism of ohmic contact formation.
- Electrical and Electronic Equipment
- Inorganic Chemistry