Schottky and Ohmic Au contacts on GaAs: Microscopic and electrical investigation

Journal Article · Tue Jul 01 04:00:00 EDT 1986 · J. Vac. Sci. Technol., B; (United States)

DOI:https://doi.org/10.1116/1.583536· OSTI ID:5531124

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

We report here a systematic study which uses electrical device measurements and transmission electron microscopy (TEM) methods to investigate the electrical, morphological, and structural properties of Au/GaAs Schottky diodes. The electrical characteristics of Au diodes formed on atomically clean and air-exposed GaAs(110) surfaces are found to change from rectifying to Ohmic behavior after annealing above the Au--Ga eutectic temperature (360 /sup 0/C). This change is shown to be due to an Ohmic-like contact at the periphery of the device. TEM studies of these structures 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. Further evidence of the correlation of the Ohmic electrical characteristics with the morphology of the periphery comes from data which indicate that the removal of these Au crystallites by mesa etching is also accompanied with the elimination of the Ohmic current. The morphology of the overlayer was found to depend strongly on annealing and surface treatment. TEM indicates that 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. For comparison to practical structures, 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.

• Research Organization: Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5531124
• Journal Information: J. Vac. Sci. Technol., B; (United States), Journal Name: J. Vac. Sci. Technol., B; (United States) Vol. 4:4; ISSN JVTBD
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420800* -- Engineering-- Electronic Circuits & Devices-- (-1989)
ARSENIC COMPOUNDS
ARSENIDES
ATOM TRANSPORT
CRYSTAL STRUCTURE
DIFFUSION
ELECTRICAL PROPERTIES
ELEMENTS
GALLIUM ARSENIDES
GALLIUM COMPOUNDS
GOLD
INTERFACES
METALS
MORPHOLOGY
NEUTRAL-PARTICLE TRANSPORT
PHYSICAL PROPERTIES
PNICTIDES
RADIATION TRANSPORT
SCHOTTKY BARRIER DIODES
SEMICONDUCTOR DEVICES
SEMICONDUCTOR DIODES
TRANSITION ELEMENTS