ABSTRACT
Silicon is the most important semiconductor material in the microelectronic industry. There have been
several attempts to increase the material variety that is compatible with Si technologies. Silicon-
germanium alloys and heterojunctions will extend the performance of future Si-based devices. However,
the Si1xGex on Si(0 0 1) system exhibits severe limitations. Examples include the existence of a critical thickness for perfect pseudomorphic growth, which depends on the amount of germanium (the
introduced strain). In addition, the main band offset between Si and strained SiGe is located in the
valence band, that is, this system is much better suited for hole channel than for electron channel
devices.
