This wonder material called Graphene is much surprising, it
is a form of carbon famous for bring stronger than steel and more conductive
than copper. Yeah, here we are again adding wonders to the list, add making
light.
Researchers have developed a light-emitting graphene
transistor that works in the same way as the filament in a light bulb. And it
is the world’s thinnest light bulb, said James Hone, a mechanical engineer at
Columbia University.
Scientists have long wanted to create a teensy
light bulb to place on a chip, enabling what is called has a photonic circuits,
which runs on light rather than an electric current. The problem has been size
and temperature. Normal tungsten filament must get extremely hot before they
can produce visible light. But the new Graphene device is so efficient and
tiny, the resulting technology could offer new ways to make displays or study
high temperature phenomena at small scales.
When electric current is passed through an incandescent
filament, usually made of tungsten……..the filament heats and glows. Electrons moving
through the material knock against electrons in the filament’s atoms, giving
them energy. Those electrons return to their former energy levels and emits
photons in the process.
In the new study scientists used strips of graphene a few
microns across and from 6.5 to 14 micron in length, each spanning a trench of
silicon like bridge. An electron was attached to the ends of each graphene
strip. Just like tungsten, run a current through graphene and the material will
light up. But there is added twist, as graphene conducts heat less efficiently
as temperature increases, which means the heat stays in a spot in the center,
rather than being relatively evenly distributed as in a tungsten filament.
A researcher, Myung-Ho said, tapping the heat in one region
makes lighting more efficient. As for why this is the first time light has been
made from graphene, Yu Daniel, study co-leader, noted that graphene is usually
embedded in or in contact with a substrate.
Physically suspending the graphene eliminates pathways in
which heat can escape. The light from the graphene is also reflected off the silicon
that each piece was suspended in front of. The reflected light interferes with
the emitted light, producing a pattern of emission with peaks at different wavelengths.
That opened up another possibility; turning the light by varying the distance
of the silicon.
This wonder material is just amazing, discovery in physics
will never end, as one mystery is solved, it open a much bigger door of
questions so good luck in discovering more stuff…..
CREDIT: Young Duck Kim-Columbia Engineering.
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