Visible light emissions and single-electron tunneling from silicon quantum dots embedded in Si-rich ${\mathrm{SiO}}_2$ deposited in plasma phase

Visible photoluminescence at room temperature was observed in silicon-rich oxide films deposited by an electron cyclotron resonance plasma with a mixture of silane and oxygen. The photocurrent measurement also exhibits evidence of stable luminescence at 3.0- and 2.2-eV bands from the silicon-enriched parts of oxide films. The emission energy range corresponds to a crystallite size of 10–35 Å. A model of the quantum dot is suggested from an infrared spectroscopic measurement of the chemical bond structures of oxide films. The stable light emissions from both the as-deposited and the rapid thermal annealed samples are related to the oxygen passivation of grain boundaries in the Si nanocrystallites. The current-voltage measurement for Si-rich oxides shows discontinuous currents around zero voltage at room temperature. The jump of the conductance relates to the Coulomb blockade in the array of Si quantum dots.