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Interfacial Diffusion/Reaction and Electrical Properties of Pd Ultra-Thin Film on Sic at Different Annealing Temperatures

Published online by Cambridge University Press:  10 February 2011

W. Lu ,
D. T. Shi ,
W. E. Collins ,
H. Chen  and
A. Burger
W. Lu
Affiliation:
Dept. of Physics, and Center for Photonic Materials and Devices Fisk University, Nashville, TN 37208
D. T. Shi
Affiliation:
Dept. of Physics, and Center for Photonic Materials and Devices Fisk University, Nashville, TN 37208
W. E. Collins
Affiliation:
Dept. of Physics, and Center for Photonic Materials and Devices Fisk University, Nashville, TN 37208
H. Chen
Affiliation:
Dept. of Physics, and Center for Photonic Materials and Devices Fisk University, Nashville, TN 37208
A. Burger
Affiliation:
Dept. of Physics, and Center for Photonic Materials and Devices Fisk University, Nashville, TN 37208
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Abstract

Pd/SiC has been used as a high temperature hydrocarbon and hydrogen gas sensor in environmental and aeronautical applications. In this work, the relationships between diffusion, reaction, and interfacial chemical composition with electrical properties for Pd ultra-thin films on 6H-SiC (∼< 30Å) are studied at different annealing temperatures.

Ultra-thin film Pd on 6H-SiC has been prepared by the RF sputtering method. The Schottky barrier heights are measured by XPS for an unannealed sample and samples annealed from 100°C to 400°C for 30 minutes, respectively. No significant change in the Schottky barrier height of the Pd/SiC contact was found in the temperature range. The morphology from UHV-STM and AFM show that the unannealed Pd thin film had good uniformity across the SiC substrate, and the Pd has dispersed, and then partially aggregated into rounded shaped precipitates with increasing annealing temperatures. At 400°C, all Pd metal has reacted and formed to silicides. From XPS, Pd2Si was found on the surface after annealing, and almost all Pd has reacted to become Pd2Si after annealing at 400°C. No other silicide was found. The intensity of Pd on XPS decreases enormously at 400°C. This is explained if Pd has diffused into SiC. The Pd diffusion and the formation of Pd silicides do not significantly affect the Schottky barrier height. The SiO2 was found at the top of surface after annealing, and increased in amount with increasing annealing temperature. The SiO2 formation was accelerated by the presence of Pd. Pd may play a role in absorbing oxygen, and activating Si from SiC to form SiO2.

Key Words: Pd thin film, SiC, X-ray photoelectron spectroscopy, scanning tunneling microscopy, and atomic force microscopy.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 512: Symposium F – Wide Bandgap Semiconductors for High Power, High Frequency , 1998 , 339
Copyright
Copyright © Materials Research Society 1998

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References

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