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 the dominance of silicon in microelectronics well into the 21st century. This momentum stimulates development of new materia Is which should further enhance the performance of silicon microelectronic circuitry. Such materials must, however, be compatible with silicon processing technologies. Major advances in silicon technology are now in prospect due to breakthroughs in molecular beam epitaxy (MBE) growth which have occurred over the last decade and which have enabled silicon to be alloyed to its nearest neighbours in the periodic table - Ge, C, and Sn. The Si/Si1-xGex heteroepitaxial material system in particular is emerging as a strong candidate to form a silicon-based heterojunction technology. The incorporation of thin, strained, (pseudomorphic) layers of Si1-xGex in silicon allows significant valence band and conduction band edge misalignments to be realized along with appreciable reductions in bandgap energies. Bandgap engineering-such a powerful tool for modifying semiconducting properties (and previously the reserve of compound semiconductors) - thus becomes accessible to the mainstream microelectronics material. This review considers the dramatic impact SiGe could have on future silicon microelectronics.