Abstract:
This paper presents nonvolatile memory characteristics of a quantum dot gate floating gate nonvolatile memory
(QDNVM) that employs SiOx-cladded silicon quantum dots as
discrete charge storage nodes of the floating gate. The cladding
of Si quantum dots and control of their size are shown to result
in a faster access and improved retention time. The floating gate
is formed by site-specific self-assembly of SiOx-Si quantum dots
on the tunnel oxide layer over the p-region between source and
drain of an n-channel field-effect transistor (FET). Experimental
data on fabricated long channel devices show threshold voltage
shift as a function of duration and magnitude of the electrical
stress applied during the “Write” operation. Current–voltage
characteristics (ID–VD and ID–VG) are presented before and
after stress. The electrical characteristics are explained using
a quantum dot gate FET model which includes the threshold
voltage shift (VTH) as a function of charge on the floating gate
quantum dots due to applied electrical stress.
