A low power 77 K nano-memory with single electron nano-crystal storage

Abstract

We present experimental results of a threshold-shifting nano-memory. The observations are consistent with single electron storage in nano-crystals and offer possible evidence of Coulomb blockade at 77 K. The nano-memory consists of a silicon field-effect transistor with nano-crystals of silicon placed in the gate oxide in close proximity of the inversion surface. Electron charge is stored in these isolated 5-10 nm size nano-crystals which are separated from each other by >5 nm of SiO/sub 2/ and from the inversion layer on the substrate surface by sub-2 nm of SiO/sub 2/. Charge is injected from the inversion layer and its storage in the nano-crystals causes a shift in the threshold voltage which is sensed via current. The magnitude of this threshold shift is relatable to the charge in the nano-crystals, oxide thicknesses, and other device parameters. The uniqueness of this work is that this is the first memory utilizing single electron storage in a mainstream silicon technology which operates at low powers and yet does not sacrifice the drive current, reproducibility, and noise margin needs of a practical memory technology. It should also be possible to extend the concept to room temperature by utilizing the suspected Coulomb blockade behavior in nanocrystals of 3 nm size.