Schottky and ''ohmic'' Au contacts on GaAs, microscopic and electrical investigation

Conference · Sat Feb 01 04:00:00 EST 1986

OSTI ID:6112778

Liliental-Weber, Z; Gronsky, R; Washburn, J; Newman, N; Spicer, W E; Weber, E R

Electrical device measurements and transmission electron microscopy (TEM) methods were used to investigate the electrical, morphological and structural properties of Au/GaAs Schottky diodes. The electrical charcteristics of Au diodes formed on automically clean and air-exposed GaAs (110) surfaces change from rectifying to ohmic behavior after annealing above the Au-Ga eutectic temperature (360/sup 0/C), owing to an ohmic-like contact at the periphery of the device. TEM indicate that the ohmic peripheral current pathway can be correlated with the formation of near-surface Ga-rich Au crystallites at the diode circumference upon annealing. Removal of these Au crystallites by mesa-etching is also accompanied by the elimination of the ohmic current. The morphology of the overlayer depends strongly on annealing and surface treatment. The interface is flat and abrupt for all unannealed diodes, as well as for annealed diodes formed on atomically clean surfaces. For annealed diodes formed on the air-exposed surfaces, the metal-semiconductor interface contains large metallic protrusions extending up to several hundred Angstroms into the semiconductor. The morphology of annealed diodes formed using typical commercial processing technology (i.e. formed on chemically prepared (100) surfaces annealed in forming gas) was also investigated using TEM. The interface for these structures is more complex than interfaces formed on the atomically clean and air-exposed cleaved (110) surfaces. Au diffuses through the interfacial native oxide layer and forms islands in intimate contact with the semiconductor.

• Research Organization: Lawrence Berkeley Lab., CA (USA); Stanford Univ., CA (USA). Stanford Electronics Labs.
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6112778
• Report Number(s): LBL-21010; CONF-860159-1; ON: DE86007610
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603 -- Materials-- Properties
42 ENGINEERING
420800* -- Engineering-- Electronic Circuits & Devices-- (-1989)
ANNEALING
ARSENIC COMPOUNDS
ARSENIDES
CORRELATIONS
CRYSTAL STRUCTURE
ELECTRIC CONTACTS
ELECTRICAL EQUIPMENT
ELECTRICAL PROPERTIES
ELECTRON MICROSCOPY
ELEMENTS
EQUIPMENT
GALLIUM ARSENIDES
GALLIUM COMPOUNDS
GOLD
HEAT TREATMENTS
INTERFACES
MATERIALS
METALS
MICROSCOPY
MICROSTRUCTURE
N-TYPE CONDUCTORS
PHYSICAL PROPERTIES
PNICTIDES
SCHOTTKY BARRIER DIODES
SEMICONDUCTOR DEVICES
SEMICONDUCTOR DIODES
SEMICONDUCTOR MATERIALS
TRANSITION ELEMENTS
TRANSMISSION ELECTRON MICROSCOPY