In the previous chapters, it has been demonstrated that the ETM as well as the LSM cannot explain charge trapping in NBTI. In particular the ETM, suggested by Huard et al. [58], suffers from several weaknesses, such as a too weak field dependence or a too short relaxation phase (see Section 4.2.9). However, the most severe deficiency is the lack of an appreciable temperature activation. As a result, there must exist an additional temperature-activated process coupled to elastic tunneling. Both subprocesses constitute a common trapping mechanism capturing the field as well as the temperature dependence.
The SRH equations (2.74) and (2.75) form the basis for the inelastic tunneling
transitions mentioned before. They describe charge carrier transitions via an
undefined temperature-activated process, which has not to be specified within the
general framework of the standard SRH. Besides NBTI, the underlying concept has
also been employed as a description for other charge trapping phenomena, such as
random telegraph noise (RTN). The latter has been intensively investigated by means
of time constant plots, which show 
and 
as a function of the oxide field
or the gate voltage [56, 55, 124, 125]. Recently, they have been used as
one way to tackle the NBTI phenomenon experimentally [53, 51]. Since
these plots reveal the behavior of single defects, they provide an insight
into the microscopic processes behind a charge capture or emission event.
Therefore, they will be used to evaluate the NBTI models presented in this
chapter.