ABSTRACT
High-mobility channels will typically be used for high-performance applications, while silicon (Si) devices will be required for low power thereby highlighting the need for integration on a Si-based platform. The low bandgap of germanium (Ge) is a concern for keeping the off-state leakage in the devices under control. The off-state leakage is basically the sum of the subthreshold leakage, gate leakage, and junction leakage. Apart from the off-state leakage reduction, the challenges of Ge based high-mobility channels are significant: the growth of high-quality Ge layers on Si substrates, gate stack with low interface and high-κ dielectric defects, source/drain engineering, and the introduction of efficient strain booster technologies. The use of SiGe and Ge layers opens up the possibility not only to introduce strain into the devices but also to engineer the bandgap and more importantly the conduction and/or the valence band offsets in the structures.
