During the last 25 years (after the growth of the first pseudomorphic GeSi strained layers on Si by Erich Kasper in Germany) we have seen a steady accu mulation of new materials and devices with enhanced performance made pos sible by strain. 1989-1999 have been very good years for the strained-Iayer devices. Several breakthroughs were made in the growth and doping technology of strained layers. New devices were fabricated as a results of these break throughs. Before the advent of strain layer epitaxy short wavelength (violet to green) and mid-IR (2 to 5 f. Lm) regions of the spectrum were not...