1. R. A. Vaia and E. P. Giannelis, MRS Bulletin, 26, 394 (2001).
2. C. Kittel, Introduction to Solid State Physics (Wiley, New York, 1996) Chapter 6.
3. L. Esaki, in Synthetic Modulated Structures, L. L. Chang and B. C. Geissen, eds. (Academic, Orlando, 1985) Chapter 1.
4. G. Burns, Solid State Physics (Academic, San Diego, 1985) Chapter 18.
5. D. A. B. Miller, Opt. Photon. News, February, 257 (1990).