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Browse Prior Art Database

SILICIDE OHMIC CONTACT TO P-TYPE GAAS

IP.com Disclosure Number: IPCOM000041987D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Jackson, TN: AUTHOR [+2]

Abstract

An improved thermal stability ohmic contact for p-type GaAs is a co-evaporated layer of Si and a base metal that reacts strongly with the dopant element in the layer and the group V element of the GaAs. There will be a large amount of As vacancies in GaAs near the metal/GaAs interface, and a p+ layer will be formed when the dopant atoms diffuse across the interface and occupy these As vacant sites. The resulting p+ layer is essential for a low resistance ohmic contact. Satisfactory metals are, for example, Ni and Pt, with Ni preferred.

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SILICIDE OHMIC CONTACT TO P-TYPE GAAS

An improved thermal stability ohmic contact for p-type GaAs is a co- evaporated layer of Si and a base metal that reacts strongly with the dopant element in the layer and the group V element of the GaAs. There will be a large amount of As vacancies in GaAs near the metal/GaAs interface, and a p+ layer will be formed when the dopant atoms diffuse across the interface and occupy these As vacant sites. The resulting p+ layer is essential for a low resistance ohmic contact. Satisfactory metals are, for example, Ni and Pt, with Ni preferred. Since Ni is known to react only with As in GaAs to form the hexagonal NiAs phase, and is also quite reactive to Si, the contact using a co- evaporated (or co-sputtered) Ni-Si layer will provide the following advantages: (a) Since the NiSi (hexagonal) phase is a stable phase between Ni and Si at temperatures 300-700OEC, and the NiAs (hexagonal) is the only stable phase between Ni and As, the contact will be stable in the temperature range 300- 700OEC. (b) No second metal is needed to ensure the uniformity of the contact.
(c) The contact behavior can be controlled by the Ni/Si mass ratio.

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