A silicon nanocrystals based memory

TLDR

The limited size and capacitance of silicon nanocrystals (~5 nm) restrict the number of stored electrons, and while Coulomb blockade may play a role, it is not essential for operation. The authors propose a memory structure that shifts its threshold voltage by storing charge in silicon nanocrystals. The device operates via direct tunneling and electron storage in the nanocrystals. Experiments show threshold shifts of 0.2–0.4 V, sub‑100‑ns read/write times at voltages below 2.5 V, retention over days to weeks, and over 10⁹ cycles without degradation, demonstrating high‑density, low‑power performance.

Abstract

A new memory structure using threshold shifting from charge stored in nanocrystals of silicon (≊5nm in size) is described. The devices utilize direct tunneling and storage of electrons in the nanocrystals. The limited size and capacitance of the nanocrystals limit the numbers of stored electrons. Coulomb blockade effects may be important in these structures but are not necessary for their operation. The threshold shifts of 0.2–0.4 V with read and write times less than 100’s of a nanosecond at operating voltages below 2.5 V have been obtained experimentally. The retention times are measured in days and weeks, and the structures have been operated in an excess of 109 cycles without degradation in performance. This nanomemory exhibits characteristics necessary for high density and low power.