1. W. Hansen, J. P. Kotthaus, and U. Merkt, in Semiconductors and Semimetals. edited by M. Reed (Academic, London, 1992), Vol, 35, p. 279
2. see also P. Bönsck, D. Wüllner, T. Schrimpf, A. Schlachetzki, and R. Lacmann, J. Electrochem. Soc. 145, 1273 (1998)
3. and J. Wang, D. A. Thompson, and J. G. Simmons, J. Electrochem. Soc. 145, 2931 (1998).
4. D. W. L. Tolfree, Rep. Prog. Phys. 61, 313 (1998).
5. Y. Xia and G.M. Whitesides, Annu. Rev. Mater. Sci. 28, 153 (1998)