Hostname: page-component-586b7cd67f-dlnhk Total loading time: 0 Render date: 2024-11-25T17:28:05.670Z Has data issue: false hasContentIssue false
  • English
  • Français

In-Situ Annealing Transmission Electron Microscopy Study of Pd/Ge/Pd/GaAs Interfacial Reactions

Published online by Cambridge University Press:  10 February 2011

F. Radulescu ,
J.M. Mccarthy  and
E. A. Stach
F. Radulescu
Affiliation:
Department of Materials Science and Engineering, Oregon Graduate Institute of Science and Technology, P.O. Box 91000, Portland, Oregon, 97291
J.M. Mccarthy
Affiliation:
Department of Materials Science and Engineering, Oregon Graduate Institute of Science and Technology, P.O. Box 91000, Portland, Oregon, 97291
E. A. Stach
Affiliation:
National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California, 94720
Get access

Abstract

In-situ TEM annealing experiments on the Pd (20 nm) / a-Ge (150 nm) / Pd (50 nm) GaAs ohmic contact system have permitted real time determination of the evolution of contact microstructure. As-deposited cross-sectional samples of equal thickness were prepared using a focused ion beam (FIB) method and then subjected to in-situ annealing at temperatures between 130-400 °C. Excluding Pd-GaAs interactions, four sequential solid state reactions were observed during annealing of the Pd:Ge thin films. First, interdiffusion of the Pd and Ge layers occurred, followed by formation of the hexagonal Pd2Ge phase. This hexagonal phase then transformed into orthorhombic PdGe, followed by solid state epitaxial growth of Ge at the contact / GaAs interface. The kinetics of the solid state reactions, which occur during ohmic contact formation, were determined by measuring the grain growth rates associated with each phase from the videotape observations. These data agreed with a previous study that measured the activation energies through a differential scanning calorimetry (DSC) method. We established that the Ge transport to the GaAs interface was dependent upon the grain size of the PdGe phase. The nucleation and growth of this phase was demonstrated to have a significant effect on the solid phase epitaxial growth of Ge on GaAs. These findings allowed us to engineer an improved two step annealing procedure that would control the shape and size of the PdGe grains. Based on these results, we have established the suitability of combining FIB sample preparation with in-situ cross-sectional transmission electron microscopy (TEM) annealing for studying thin film solid-state reactions.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 589 , 1999 , 179
Copyright
Copyright © Materials Research Society 2001

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1.Marshall, E. D., Zhang, B., Wang, L. C., Jiao, P. F., Chen, W. X., Sawada, T., Lau, S. S., Kavanagh, K. L. and Kuech, T. F., J. Appl. Phys. 62, 942 (1987)Google Scholar
2.Sands, T., Keramidas, V. G., Yu, A. J., Yu, K-M., Gronsky, R. and Washburn, J., J. Mater. Res. 2, 262 (1987)Google Scholar
3.Ottaviani, G., Canali, C., Ferrari, G., Majni, G., Prudenziati, M. and Lau, S. S., Thin Solid Films 47, 187 (1977)Google Scholar
4.Marshall, E.D., Lau, S.S., Palmstrom, C.J., Sands, T., Schwartz, C.L., Schwarz, S.A., Harbison, J.P., and Florez, L.T., Mater. Res. Soc. Symp. Proc. 148, 163 (1989)Google Scholar
5.Radulescu, F. and McCarthy, J.M., J. Appl. Phys. 86, 995 (1999)Google Scholar
6.Basile, D.P., Boylan, R., Baker, B., Hayes, K. and Soza, D., Mat. Res. Soc. Symp. Proc. 254, 23 (1992)Google Scholar
7.Scott, D. M., Pai, C. S. and Lau, S. S., SPIE Conf. Proc. 463, 40 (1984)Google Scholar
8.Palmstrom, C.J. et al. , J. Appl. Phys. 67, 334 (1990)Google Scholar