By BizLED Bureau
July 11, 2017: In the last two years, gallium nitride (GaN) LED has advanced significantly, yet a lot more can be expected from this technology. Despite significant advancements, GaN on GaN LED technology fails to meet the expected light quality factors that the users associate with natural sunlight such as natural daylight. This limitation can be partly blamed on the LED industry, which mainly focuses on increasing lumen per watt and gives less attention on other important aspects like whiteness rendering, color, beam pattern, total light output, etc. But studies have found that GaN on GaN LED technology can provide better light quality with regard to color rendering, bright white color, etc, and at the same time can also provide better lumen per wafer if compared to normal LEDs.
GaN on GaN LED technology was first introduced in 2012 along with the launch of the first single beam 50W equivalent LED MR16. Within two years, it has advanced so much that it can offer the same efficiency levels as traditional GaN-based LEDs, while delivering much higher light quality, and much higher power density.
Advancements in GaN on GaN LEDs
The latest and more advanced GaN on GaN LEDs can deliver better light output. They exhibit better wall-plug efficiency of 80% at 85°C, and 65% at 150 A/cm2, with current density that is five or six times higher than for the LEDs based on foreign substrates. This advancement in GaN on GaN LEDs has made GaN on GaN LEDs suitable for LED-based systems that run at high temperature as well as high current densities, and where normal LEDs fail to perform.
Quality of light
Quality of light, an important property of LED, has many aspects like color fidelity that is measured by CRI, that is color rendering index?Ra and special index R9. R9 is important for deep red color and the color of human skin. Most of the LED products are developed aiming for Ra between 80 and R9 above 0. This is because experts believe that such values are sufficient. There are also options for higher-end with values of Ra=95 and R9=95. Such high CRI needs photons at the end of the spectrum, which makes it expensive. But with the superior advancements in GaN on GaN LED technology, it has become more efficient and can help to support higher CRI.
Now, GaN on GaN can excite OBAs
Whiteness rendering, an important measure of light quality, is often ignored. But its use in optical brightening agents (OBAs) is essential in manufacturing white products. Many white objects like paper, fabrics, etc contain OBAs to enhance whiteness. OBAs absorb short-wavelength light from sunlight or incandescent and halogen lamps, and convert it into blue light. It enables a color shift that is seen as bright white. However, OBAs do not work well with conventional LEDs. Conventional LEDs use blue light and cannot deliver short-wavelength radiation. Hence, they fail to attract OBAs, and this makes white objects look dull and yellow.
But now, with advancements in GaN on GaN, it can excite OBAs. For instance, Soraa?s Gen3 LED delivers full spectrum light, which excites OBAs and renders whiteness perfectly and other colors.
Today, about 95% of GaN on GaN LEDs are manufactured on sapphire wafers but the industry is also considering to use cheaper Si wafers to increase production and enable its usage more widely. Research firm IHS Inc predicts that GaN-on-Silicon LEDs will increase market share from 1% currently to 40% by 2020.
However, not all high CRI LEDs give out similar performance with regard to quality of light. For example, the quality of light for violet GaN on GaN LED is higher with respect to efficacy levels and input power. So, GaN on GaN LED can now deliver quality of light that we associate with natural sunlight.
GaN on GaN LED can deliver small sizes of LED source
Another advantage with GaN on GaN LED is that it can deliver small sizes of LED source, yet by maintaining high light output or high brightness with high quality of light. This immensely helps when narrow beams of light are required, which is easier to control from smaller sources. Soraa has recently launched a GaN on GaN LED lamp with center beam power, R9 of 95 and CRI Ra, whiteness rendering capability, with a single source beam.