A light-emitting diode (LED)
is a two-lead semiconductor light source.
It is a p–n junction diode that
emits light when activated. Electron and holes are able to combine within the
device if voltage is applied and release some kind of energy called photons.
Early LEDs were often used as indicator lamps for electronic devices, replacing
small incandescent bulbs.
GaN based LEDs is one of the
technology learned in order to maximize light extraction technology in our
industry. GaN was first investigated as a potential material for LEDs in the
late 1960s by Paul Maruska and Jacques Pankove at the Radio Corporation of
America (RCA) and in later years additionally by Isamu Akasaki and co-workers
at university in Japan, Akasaki I et al. The
semiconductor Gallium Nitride was a material that was of interest at the time
because of its high band gap with the potential for developing a blue LED or
is a direct band gap semiconductor material with a 3.45 eV band gap which
corresponds to near ultraviolet (UV) light (364 nm), Steven
P et al.
efficiency light-emitting diodes (LEDs) have increasingly become a viable light
source for illumination applications, such as traffic light, interior/exterior
lighting and full color displays. However, current commercial GaN LEDs grown on
the c-plane of the wurtzite crystal are negatively impacted by the quantum
confined Stark effect (QCSE) due to the large polarization-related spontaneous
and piezoelectric fields,
Bernardini F et al and lead to internal quantum efficiency.
based LEDs is known in development in blue light and recent research have led
to the realization of high-efficiency white solid-state lighting. GaN white LEDs exhibit luminous efficacy and higher
external quantum efficiencies. This has enabled LEDs to compete with
traditional lighting technologies, such as incandescent and compact fluorescent
(CFL) lighting. Further improvements in materials quality and cost reduction
are necessary for widespread adoption of LEDs for lighting.
Few methods have been tested to improve LEDs light extraction technology
which is improvement of photon extraction efficiency of GaN-based LEDs.