Thermally stable ohmic contacts to n -type GaAs. VI. InW contact metal

Journal Article · Tue May 01 04:00:00 EDT 1990 · Journal of Applied Physics; (USA)

DOI:https://doi.org/10.1063/1.344955· OSTI ID:6906466

Kim, H; Murakami, M; Price, W H; Norcott, M ^[1]

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1. IBM Research Division, T. J. Watson Research Center, Yorktown Heights, New York 10598 (USA)

The electrical properties and thermal stability of In/W Ohmic contacts in {ital n}-type GaAs were studied by analyzing interfacial microstructure using cross-sectional transmission electron microscopy and measuring the contact resistances by transmission line method. Indium layers with various thicknesses were deposited directly on GaAs substrates, which were kept at room or liquid-nitrogen temperature. The lower contact resistances ({ital R}{sub {ital c}}) were obtained when the contacts were prepared at liquid-nitrogen temperature. These low {ital R}{sub {ital c}} values were due to formation of large-areal In{sub {ital x}}Ga{sub 1{minus}{ital x}}As phases on the GaAs substrate after annealing at temperatures higher than 600 {degree}C. The In layer thicknesses of the In/W contacts prepared at liquid-nitrogen temperature strongly affected the contact resistances as well as the thermal stability after contact formation. The optimum In layer thickness which provided the best electrical properties and thermal stability was determined to be 3 nm. The In(3 nm)/W contacts yielded {ital R}{sub {ital c}} values less than 0.2 {Omega} mm and the {ital R}{sub {ital c}} values did not deteriorate after annealing at 400 {degree}C for more than 20 h. The contacts with In layer thicknesses thinner than 3 nm resulted in higher {ital R}{sub {ital c}} values due to insufficient In{sub {ital x}}Ga{sub 1{minus}{ital x}}As phases at the metal/GaAs interfaces. The contacts with In layer thicknesses thicker than 3 nm resulted in poor thermal stability due to formation of large amounts of In-rich In(Ga,As) phases with low melting points. The present In(3 nm)/W Ohmic contacts are believed to be the simplest metallurgy with excellent electrical properties and thermal stability among In-based Ohmic contacts.

• OSTI ID: 6906466
• Journal Information: Journal of Applied Physics; (USA), Journal Name: Journal of Applied Physics; (USA) Vol. 67:9; ISSN 0021-8979; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ARSENIC COMPOUNDS
ARSENIDES
CRYSTAL STRUCTURE
ELECTRICAL PROPERTIES
ELECTRON MICROSCOPY
ELEMENTS
GALLIUM ARSENIDES
GALLIUM COMPOUNDS
INDIUM
INTERFACES
LAYERS
LOW TEMPERATURE
MATERIALS
MEDIUM TEMPERATURE
METALS
MICROSCOPY
MICROSTRUCTURE
N-TYPE CONDUCTORS
PHYSICAL PROPERTIES
PNICTIDES
SEMICONDUCTOR MATERIALS
STABILITY
TRANSITION ELEMENTS
TRANSMISSION ELECTRON MICROSCOPY
TUNGSTEN