1 J.B. Casady and R.W. Johnson, Solid-State Electronics 39(10) (1996) 1409. 2 H. Matsunami. S. Nishino and H. Ono, IEEE Trans., Electron Devices ED-28, (1981) 1235. 3 Y. Sun and T. Miyasato, J. Appl. Phys. 82(5) (1997) 2334. 4 S. Kerdiles. R. Rizk, A. Pereg-Rodrigues, B. Garrido, O. Gonzalez-Varona, L. Calvo-Barrio and T.R.Morante, Solid-State Electronics 42(12) (1998) 2315. 5 Q. Wahab, M.R. Sardela, Jr, L. Hultman. A. Henry, M. Willander, E. Janzen and J.-E. Sundgren,Appl. Phys. Lett. 65(6) (1994) 725. 6 H. Okumura, E. Sakuma, J.H. Lee, H. Mukaida, S. Misawa, K. Endo and S. Yoshida, J. Appl. Phys.61(3) (1987) 1134. 7 Y. Sun and T. Miyasato. J. Appl. Phys. 64(11) (1998) 6451.