Description:

A single-electron memory, in which a bit of information is stored by one electron, has been demonstrated at room temperature. The memory is a floating gate metal-oxide-semiconductor transistor in silicon with a channel width (~10 nanometers) smaller than the Debye screening length of a single electron and a nanoscale polysilicon dot (~7 nanometers by 7 nanometers) as the floating gate embedded between the channel and the control gate. Storing one electron on the floating gate screens the entire channel from the potential on the control gate and leads to (i) a discrete shift in the threshold voltage, (ii) a staircase relation between the charging voltage and the shift, and (iii) a self-limiting charging process. The structure and fabrication of the memory should be compatible with future ultralarge-scale integrated circuits.

Above is an SEM image of the narrow silicon channel with the polysilicon dot on top, before size reduction by thermal oxidation. The width of the channel and the size of the dot are both 50 nm. The lines in the buried oxide, included for easy alignment, come from the second-level EBL and have no effect on device behavior.

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