SILICON-GERMANIUM HETEROSTRUCTURES - ADVANCED MATERIALS AND DEVICES FOR SILICON TECHNOLOGY - REVIEW

The continuing massive investment in silicon technology and the unique physical and chemical properties of the Si-SiO2 system will ensure th e dominance of silicon in microelectronics well into the 21st century. This momentum stimulates development of new materia Is which should f urther enhance the performance of silicon microelectronic circuitry. S uch materials must, however, be compatible with silicon processing tec hnologies. Major advances in silicon technology are now in prospect du e to breakthroughs in molecular beam epitaxy (MBE) growth which have o ccurred over the last decade and which have enabled silicon to be allo yed to its nearest neighbours in the periodic table - Ge, C, and Sn. T he Si/Si1-xGex heteroepitaxial material system in particular is emergi ng as a strong candidate to form a silicon-based heterojunction techno logy. The incorporation of thin, strained, (pseudomorphic) layers of S i1-xGex in silicon allows significant valence band and conduction band edge misalignments to be realized along with appreciable reductions i n bandgap energies. Bandgap engineering-such a powerful tool for modif ying semiconducting properties (and previously the reserve of compound semiconductors) - thus becomes accessible to the mainstream microelec tronics material. This review considers the dramatic impact SiGe could have on future silicon microelectronics.