Towards single-trap spectroscopy : Generation-recombination noise in UTBOX SOI nMOSFETs
Résumé
An overview is given on the possibilities of using generation-
recombination (GR) noise as a tool for defect spectroscopy
in semiconductor materials and devices. The
method is illustrated by n-channel MOSFETs fabricated
on silicon-on-insulator (SOI) substrates with an ultra-thin
buried oxide (UTBOX). As will be shown, the use of fully
depleted (FD) UTBOX devices offers some unique
opportunities and challenges. In the first instance, one
can apply the standard GR noise spectroscopy in function
of the temperature to derive the relevant deep-level parameters
like the activation energy, the capture cross section
and the concentration. In addition, some new type of
spectroscopy can be applied to defects in the silicon film
by exploiting the front- and/or back-gate bias dependence
of the Lorentzian noise parameters. Finally, it is shown
that for small geometry transistors the GR noise is generated
by one or only a few centres. This becomes obvious
in the time domain, where the channel current exhibits
random telegraph signal (RTS) fluctuations. The up and
down time constants and the relative RTS amplitude can
be used to derive the GR centre parameters and, moreover,
its spatial location, when combined with numerical
device simulations.