In this chapter, a general description of the main MOSFET degradation mechanisms considered in this work is given. The proposed dissertation, while not aiming to give a complete coverage of the wide literature available on the treated topics, is meant to provide the reader with a sufficient basis to follow the discussion of the original experimental work presented in the following chapters.Most of the chapter is devoted to the Negative Bias Temperature Instability (NBTI) since this degradation mechanism pertains to most of the original experimental work on SiGe and Ge channel devices presented later in the Chaps. 4 Recent modeling attempts are focused on the central role of hole trapping mechanisms in NBTI degradation. However, the standard Shockley-Read-Hall models for carrier generation-recombination have been proven to be incapable of correctly capturing the properties of hole trapping into bulk oxide defects (Sect. 2.2.7). A physically more accurate description of the trapping mechanism, including vibrational motion of the atoms at the defect sites, is needed for reproducing the observed trapping behavior (Sect. 2.2.8). Based on these insights, a defect model compatible with a wide range of NBTI degradation observations J. Franco et al., Reliability of High Mobility SiGe Channel MOSFETs for Future