Ohmic, superconducting, shallow AuGe/Nb contacts to GaAs

Journal Article · Sat Nov 01 04:00:00 EST 1986 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.337738· OSTI ID:5186527

Gurvitch, M; Kastalsky, A; Schwarz, S; Hwang, D M; Butherus, D; Pearton, S; Gardner, C R

An emerging new class of superconductor-semiconductor devices requires Ohmic superconducting contacts which do not diffuse deeply into a semiconductor. We developed a contact to GaAs based on --150 A of AuGe covered with --2000 A of Nb annealed in reducing atmosphere at 390-420 /sup 0/C for 1-5 s. The resulting contact has linear I-V characteristics at all temperatures down to 4.2 K, resistivity of --2 x 10/sup -6/ ..cap omega.. cm/sup 2/ (--0.1 ..cap omega.. mm), and superconducting transition temperature T/sub c/ approx. >8 K. Secondary ion mass spectroscopy (SIMS) and transmission electron microscopy (TEM) studies revealed very shallow penetration of the active dopant Ge into GaAs; the upper limit for the thickness of the doped layer with Ge concentration over 10/sup 17/ cm/sup -3/ is estimated as 200-300 A. Gold, a nonactive dopant (deep level) drops to below 10/sup 18/ cm/sup -3/ within the same distance, with the possible tail extending further. Morphology and uniformity of a contact, as revealed in TEM and optical microscopy, is good, owing to the Nb overlayer which prevents AuGe from ''balling up'' upon melting. These contacts can be used in low-temperature devices and conventional devices based on GaAs.

• Research Organization: ATandT Bell Laboratories, Murray Hill, New Jersey 07974
• OSTI ID: 5186527
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 60:9; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

420201* -- Engineering-- Cryogenic Equipment & Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALLOYS
ARSENIC COMPOUNDS
ARSENIDES
ELECTRIC CONDUCTIVITY
ELECTRIC CONTACTS
ELECTRICAL EQUIPMENT
ELECTRICAL PROPERTIES
ELECTRON MICROSCOPY
ELEMENTS
EQUIPMENT
FABRICATION
GALLIUM ARSENIDES
GALLIUM COMPOUNDS
GERMANIUM ALLOYS
GOLD ALLOYS
JUNCTIONS
MASS SPECTROSCOPY
METALS
MICROSCOPY
MORPHOLOGY
NIOBIUM
PHYSICAL PROPERTIES
PNICTIDES
SPECTROSCOPY
SUPERCONDUCTING JUNCTIONS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS
TRANSITION TEMPERATURE
TRANSMISSION ELECTRON MICROSCOPY