Reach-Through Contact for Heterojunction Structures
Original Publication Date: 1986-Oct-01
Included in the Prior Art Database: 2005-Mar-09
The contact is formed using an alloy of a metal with a small percentage of an impurity ingredient that, when the alloy is fused with semiconductor material of the heterojunction structure, the metal forms an alloy with one ingredient thereof and the impurity diffuses in snowplow fashion into the heterojunction structure. As an illustration, this is accomplished using, for example, a Pd-Mg alloy in which the Mg concentration is 2% or less. When a thin film of this alloy is deposited on GaAs and heated to 500ŒC, it is converted to PdGa. The Mg diffuses/snowplows into GaAs at the interface, producing a p+ doped layer of GaAs. Since PdGa is a nearly stoichiometric compound, this reaction is very controllable.