Soraa has developed the next generation of its high external quantum efficiency GaN on GaN LEDs, which outperform the best-documented LED laboratory result by Nichia Chemical Co. at current densities of 100 A/cm2 and beyond as described in the paper, "White light emitting diodes with super-high luminous efficacy," J. Phys. D: Appl. Phys. 43, 354002).
Soraa has published a paper on its ground breaking LEDs, entitled, "Bulk GaN based violet light-emitting diodes with high efficiency at very high current density" in Applied Physics Letters, 101, 223509. In it, Soraa reports an external quantum efficiency of 68 percent at 180 A cm−2.
Soraa says its GaN on GaN LEDs handle significantly more current and emit ten times more light per unit area of LED wafer material than LEDs created by depositing GaN layers on cheaper foreign substrates like sapphire, SiC or silicon.
However, the cost of GaN substrates is huge compared to its couterparts. For example, according to Lux Research, bulk GaN currently costs about $1,900 or more for a 2" substrate, compared with $25 to $50 for a far larger 6" silicon substrate.
Having said that, Lux predicts that HVPE (the cheaper alternative to MOCVD) 2" GaN substrate costs will fall by more than 60 percent to $730 per substrate in 2020, while 4" HVPE substrate costs will fall by 40 percent to $1,340 per substrate.
Soraa's GaN on GaN technology leverages the advantages of the native substrate, including over a thousand times lower crystal defect densities that allow reliable operation at very high current densities (the same principle that enabled Blu-ray laser diodes).
In addition to superior crystal quality, the native substrate’s optical transparency and high electrical and thermal conductivity enable a very robust, simple LED design that delivers maximum performance. Another advantage of the GaN on GaN approach is that it enables considerable flexibility in the choice of crystal growth plane.
Soraa leveraged the advantages of its first generation GaN on GaN LEDs by introducing in 2012 the world’s first true full-visible-spectrum LED MR16 lamps - a superior alternative to 50-Watt halogen MR16 lamps.
