Single electron nonvolatile memory devices are fabricated using a narrow and short channel transistor and silicon nanocrystals as a floating gate. The silicon nanocrystals are deposited by very-high-frequency plasma processing. This deposition technique offers not only control of the dot size but also promises precise control of the tunnel oxide thickness. A single electron charging effect is observed for such devices at 77 K.

A study of the electrical properties of multiple tunnel junctions (MTJs) formed in a quasi one-dimensional array of randomly deposited silicon nanocrystals is presented. Nanocrystals are deposited by very-high-frequency (VHF) plasma decomposition of silane. The average dot diameter is 8 nm. The source-drain electrode separation is 30 nm. A gate electrode is employed so that the charge states in quantum dots can be controlled. A study of the source-drain current–voltage (I–V) characteristics with various gate voltages is performed. Coulomb blockade, a Coulomb staircase and Coulomb oscillations are observed at temperatures ranging from 40 K to 150 K. Single electron trapping is observed at 40 K.

A simple but potent method for electron-beam (EB) direct writing is introduced. This method is based on the use of negative electron-beam resist RD2000N. The resist offers high sensitivity to EB exposure and high resistance to halide plasma etching conditions, which is ideal for application in Si/SiO2 based nanodevice fabrication. Dot exposure shows that dots of a minimum diameter of 16 nm could be patterned using this resist. Linear arrays of dots, connected to each other by very narrow constrictions, are patterned using this resist. When transferred to a thin silicon-on-insulator layer, by reactive ion etching, this structure forms a multiple tunnel junction. Memory devices based on this multiple tunnel junction are fabricated. Memory operation is observed at 20 K.

We investigated a size fluctuation of 50 nm periodic wire pattern of GaInAsP/InP structure with a typical wire width of around 30 nm, which was fabricated by an electron beam lithography followed by wet chemical etching. The size fluctuation of the ZEP-520 positive resist pattern was reduced from 2.7 nm to 1.4 nm by using a corrected dose profile taking the proximity effect into account, and that of the quantum-wire structure after wet etching was reduced from 3.8 nm to 2.9 nm.

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