We report on a continuously emitting electroluminescent device fabricated b
y Si+-ion implantation and subsequent annealing of a SiO2 layer on a silico
n substrate. The SiO2 layer with a thickness of 250 nm was prepared by the
sol-gel technique. Four different Si+-ion energies and implantation doses w
ere applied in order to obtain a flat Si+-ion profile across the SiO2 film
thickness with an atomic Si excess of 5%. Electroluminescence (EL) occurs a
bove a low-voltage threshold (similar to5 V, 1 A/cm(2)) at one bias polarit
y only even if the device in fact does not exhibit rectifying properties. E
L microscopy reveals that EL at 295 K is emitted from a small number of bri
ght spots with diffraction-limited size. EL spectra of individual bright sp
ots were measured using an imaging spectrometer. The wide EL emission band
(situated in the red region similar to 750 nm) obtained with spatial averag
ing over the semitransparent indium-tin-oxide contact represents the envelo
pe of these individual contributions. We suggest that the EL is due to elec
tron-hole injection into Si nanocrystals which create several conductive pe
rcolation paths across the SiO2 film. Shunting current paths due to defects
exist in parallel and are probably the main factor responsible for low EL
efficiency (10(-5)%). (C) 2000 American Institute of Physics. [S0003-6951(0
0)01545-X].