Contact reactions in Pd/GaAs junctions

Journal Article · Thu Feb 01 04:00:00 EST 1979 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.326018· OSTI ID:6565529

Olowolafe, J O; Ho, P S; Hovel, H J; Lewis, J E; Woodall, J M

The solid-state reaction of thin Pd films with GaAs substrates has been investigated using Auger sputter profiling, x-ray diffraction, He-ion backscattering, and sheet-resistivity measurements. Fast diffusion and dissolution were observed for both As and Ga into Pd, which slowed down after distinct compound layers were formed. The kinetics of Pd penetration into GaAs was found to be controlled by diffusion with an activation energy of 1.4 eV. The As and Ga compounds formed as a result of contact reactions were identified to be PdAs/sub 2/ and PdGa at 250 /sup 0/C; PdAs/sub 2/, PdGa, and Pd/sub 2/Ga at 350 /sup 0/C; and PdGa at 500 /sup 0/C. For each annealing temperature a ''steady-state'' time is reached when there is no measurable change in the backscattering spectra. The sheet resistivity of the contact was found to increase with time under isothermal annealing and eventually reached a saturation value. The saturation time of resistivity change is well correlated to the steady-state time. To determine the effect of the contact reaction on device performance, p-n junction solar cells fabricated by diffusing Zn into an n-type GaAs wafer with Pd and Ag contact layers have been tested. An onset of shunting was observed on the solar devices after heat treatments above 200 /sup 0/C. Results indicated that shunting is most probably due to Pd penetration through localized defects in the p layer of GaAs.

• Research Organization: IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598
• OSTI ID: 6565529
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 50:2; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
ACTIVATION ENERGY
ALLOYS
ANNEALING
ARSENIC ALLOYS
ARSENIC COMPOUNDS
ARSENIDES
CHEMICAL REACTION KINETICS
COMPATIBILITY
DIFFUSION
DIRECT ENERGY CONVERTERS
ELECTRIC CONDUCTIVITY
ELECTRIC CONTACTS
ELECTRICAL EQUIPMENT
ELECTRICAL PROPERTIES
ELEMENTS
ENERGY
EQUIPMENT
GALLIUM ALLOYS
GALLIUM ARSENIDE SOLAR CELLS
GALLIUM ARSENIDES
GALLIUM COMPOUNDS
HEAT TREATMENTS
JUNCTIONS
KINETICS
METALS
P-N JUNCTIONS
PALLADIUM
PALLADIUM ALLOYS
PERFORMANCE
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PHYSICAL PROPERTIES
PLATINUM METAL ALLOYS
PLATINUM METALS
PNICTIDES
REACTION KINETICS
SEMICONDUCTOR JUNCTIONS
SOLAR CELLS
TRANSITION ELEMENTS