Macropore-formation on p-type-silicon
Introdution
Propst and Kohl showed 1994 that macropores on p-type-silicon can be etched. They used HF in acetonitril and moderatly doped p-type-wafers.
Stable macropore-growth on p-type-silicon
As shown in an paper from Christophersen et al. we showed that large (up to 300 micrometer), small diameters and very stabile macropores
in p-type-silicon can be etched.
Figure 1 - Macropores in p-type silicon
"Designing of an electrolyte" gives new grades of freedom for the pore etching system. We studied the influence of additives in the electrolyte for macropores in p-type silicon.
The important parameters are availability of H and oxidizing compontents for the electrochemical reaction.
Figure 2 - Influence of the electrolyte
Influence of the substrate-orientation
The macropore-growth is anisotropic in <100> and <113>-direction (the same direction were found in n-type-silicon). The growth direction depends on the surface-orientation. The macropore-walls consists of (111)-facettes -
shown by TEM-mircographs. Pore-formation is an anisotropic process
Figure 3 - Pores on a (111)-substrate
Figure 4 - Pores on a (511)-substrate
Conclusions
It is possible to get very stable pore formation in p-type silicon with organic electrolytes.
Publications:
-
Pore Formation Mechanisms for the Si-HF System
J. Carstensen, M. Christophersen, H. Föll, Mat. Sci. Eng. B, 69-70, 23 (2000)
- Crystal Orientation and Electrolyte dependence fore Macropore Nucleation and satbele Growth on p-tye-silicon
M. Christophersen, J. Carstensen, A. Feuerhake, H. Föll, Mat. Sci. Eng. B, 69-70, 194 (2000
- Properties of organic electrolytes and their influence on macropore formation in p-type silicon
M. Christophersen, J. Carstensen, K. Voigt, H. Föll, submitted to Phys. Stat. Sol. (a)
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Last modified: 08/16/02
URL: http://www.marc-christophersen.de