Ion-Implanted Evaporated Germaniun Layers as n+ Contacts to GaAs.

摘要

A method of forming a single, reliable n plus contact for discrete GaAs devices. A film of p-type Ge is deposited uniformly over the surface of a n-type GaAs substrate. Ions of phosphorous or arsenic are implanted to 5 times 10 to the 18th power ions/cc at a depth of 1500 Angstrom. The ends and the sides of the substrate and Ge layer are capped by a CVD oxide and annealed at 450 - 500 degrees for about one hour. This process over-compensates the initial p-type layers which results in the Ge layer becoming n plus. The oxide is removed by an etch process and the n plus Ge is etched to form two separate contact sections of n plus Ge. The n plus Ge is then metalized to form ohmic contacts by use of NiAu. A CVD oxide overcoat may again be applied and annealed at about 500 degrees to drive a shallow 200 - 500 angstroms, n plus germanium diffusion into the substrate. (Author)