chapter  2
41 Pages


Silicon-based heterostructures have come a long way from the use of strain as a parameter for bandgap engineering, to the present state of devices/circuits with enhanced performance compared to those obtained in bulk-Si and competing III-V compound semiconductors. Apart from the inherent performance enhancement, undoubtedly the main attraction of high mobility Si/SiGe, SiGe/strained-Si and Si/SiGeC heterostructures is their basic compatibility with standard Si processing. For any material, issues important to the device designer include bandgap difference, band alignments and mobility. The first two properties determine the class of devices that can be fabricated. For example, quantum confinement of electrons cannot occur without a conduction band discontinuity.