Abstract
Microwatt light emission from a metal–oxide–semiconductor
light-emitting diode (MOSLED) made by using ${\hbox {SiO}}_{\rm x}$ film with buried Si nanocrystals
on Si nano-pillar array is demonstrated. The Si nano-pillar array obtained
by drying the rapidly self-aggregated Ni nano-dot-masked Si substrate exhibit
size, aspect ratio, and density of 30 nm, 10, and 2.8$\,\times 10 ^{10}~{\hbox {cm}}^{-2}$, respectively.
These high-aspect-ratio Si nano-pillar array helps to enhance the Fowler–Nordheim
tunneling-based carrier injection and to facilitate the complete relaxation
on total internal reflection, thus increasing the quantum efficiency by one
order of magnitude and improving the light extraction from the nano-roughened
device surface by three times at least. The light-emission intensity, turn-on
current and power-current slope of the MOSLED are 0.2 $~{\hbox {mW/cm}}^{2}$, 20-30 $\mu {\hbox {A}}$, and ${\hbox {3}}{\pm {\hbox {0.5}}}~{\hbox {mW/A}}$, respectively.
At a biased current of 400 $\mu {\hbox
{A}}$, the highest external quantum efficiency is over 0.2%
to obtain the maximum EL power of ${> 1}~\mu
{\hbox {W}}$. Compared with the same device made on smooth
Si substrate under a power conversion ratio of 1$\,\times {\hbox {10}} ^{-4}$, such an output power performance
is enhanced by at least one order of magnitude.
© 2008 IEEE
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