Interfacial microstructure of tungsten silicide Schottky contacts to n-type GaAs
To investigate the effects of microstructure of the Schottky characteristics of WSi/sub x/ contacts to n-type GaAs, cross-sectional transmission electron microscopy, x-ray diffraction, and secondary-ion mass spectrometry have been used to study the interfacial and bulk film microstructures. The barrier heights and ideality factors of WSi/sub 0.1/ and WSi/sub 0.6/ contacts were obtained by forward current-voltage and capacitance-voltage measurements. These Schottky characteristics were found to be unrelated to the bulk film microstructure, but closely related to the interfacial microstructure at the WSi/sub x//GaAs interfaces. Both the WSi/sub 0.1//GaAs and WSi/sub 0.6//GaAs interface morphologies were observed to be stable and remain smooth during annealing at 800 /sup 0/C for 10 min, while a rough interface with W protrusions and Ga and As out-diffusion was observed in two-layer W/WSi/sub 0.6/ contacts. The stability of the WSi/sub x/ interfacial microstructure is suggested to depend on both the chemical stability of the WSi/sub x/ films with GaAs and the intervening oxides between WSi/sub x/ and GaAs. Nontrivial amounts of W and Si were observed to diffuse from the WSi/sub 0.1/ film into the GaAs substrate during annealing at 800 /sup 0/C for 10 min. Although these in-diffused impurities in the GaAs substrate do not seem to affect the Schottky characteristics after the 800 /sup 0/C annealing, they could be a potential problem in long-term stability. Of the three WSi/sub x/ film compositions, the single-layer WSi/sub 0.6/ films were found to have the least W and Si in-diffusion and thus the best thermal stability.
- Research Organization:
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598
- OSTI ID:
- 7204446
- Journal Information:
- J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 64:4; ISSN JAPIA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360102* -- Metals & Alloys-- Structure & Phase Studies
360602 -- Other Materials-- Structure & Phase Studies
ANNEALING
ARSENIC COMPOUNDS
ARSENIDES
COHERENT SCATTERING
CRYSTAL STRUCTURE
DIFFRACTION
ELECTRON MICROSCOPY
GALLIUM ARSENIDES
GALLIUM COMPOUNDS
HEAT TREATMENTS
HIGH TEMPERATURE
INTERFACES
LAYERS
MASS SPECTROSCOPY
MATERIALS
MICROSCOPY
MICROSTRUCTURE
N-TYPE CONDUCTORS
PNICTIDES
REFRACTORY METAL COMPOUNDS
SCATTERING
SCHOTTKY EFFECT
SEMICONDUCTOR MATERIALS
SILICIDES
SILICON COMPOUNDS
SPECTROSCOPY
TRANSITION ELEMENT COMPOUNDS
TRANSMISSION ELECTRON MICROSCOPY
TUNGSTEN COMPOUNDS
TUNGSTEN SILICIDES
X-RAY DIFFRACTION