A new development in GaN LEDs
A research group at UCSB led by Shuji Nakamura (the inventor of the GaN blue LED) has used a new substrate to grow GaN with a different orientation; a blue LED using this technique achieved a peak efficiency of 52% at 20mA (not sure the die size, so I can't say the current density), but the main thing is that it only drooped 14% at 10x the current. Typical white power LEDs (based on a GaN blue die with a yellow phosphor) achieve peak efficiency around 35 mA/mm^2, and show about 25-30% droop at 350 mA/mm^2. (Figures estimated from jtr1962's LED testing graphs; while the phosphor efficiency also declines at high current density, I believe this effect to be small at these values.)
If droop continues to scale as ~half the droop of existing LEDs out to >1A/mm^2, it could yield as much as 50% higher surface brightness, which as we all know means 50% more throw :devil:, plus a significant decrease in waste heat.
Of course, it'll be a while until this tech hits production, but I can wait... if only because I kinda have to...
A research group at UCSB led by Shuji Nakamura (the inventor of the GaN blue LED) has used a new substrate to grow GaN with a different orientation; a blue LED using this technique achieved a peak efficiency of 52% at 20mA (not sure the die size, so I can't say the current density), but the main thing is that it only drooped 14% at 10x the current. Typical white power LEDs (based on a GaN blue die with a yellow phosphor) achieve peak efficiency around 35 mA/mm^2, and show about 25-30% droop at 350 mA/mm^2. (Figures estimated from jtr1962's LED testing graphs; while the phosphor efficiency also declines at high current density, I believe this effect to be small at these values.)
If droop continues to scale as ~half the droop of existing LEDs out to >1A/mm^2, it could yield as much as 50% higher surface brightness, which as we all know means 50% more throw :devil:, plus a significant decrease in waste heat.
Of course, it'll be a while until this tech hits production, but I can wait... if only because I kinda have to...
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