Thermally enhanced blue light-emitting diode
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Thermally-enhanced-blue-light-emitting-diodes.pdf
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1.35 MB
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Checksum (MD5)
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Author(s)
Xue, Jin
Zhao, Yuji
Oh, Sang-Ho
Herrington, William F.
Speck, James S.
DenBaars, Steven P.
Nakamura, Shuji
Ram, Rajeev J.
Date Issued
September 2015
Journal
Applied Physics Letters
Publisher
American Institute of Physics (AIP)
Citation
Xue, Jin, Yuji Zhao, Sang-Ho Oh, William F. Herrington, James S. Speck, Steven P. DenBaars, Shuji Nakamura, and Rajeev J. Ram. “Thermally Enhanced Blue Light-Emitting Diode.” Applied Physics Letters 107, no. 12 (September 21, 2015): 121109. © 2015 AIP Publishing LLC
Version
Final published version
Abstract
We investigate thermoelectric pumping in wide-bandgap GaN based light-emitting diodes (LEDs) to take advantage of high junction temperature rather than avoiding the problem of temperature-induced efficiency droop through external cooling. We experimentally demonstrate a thermally enhanced 450 nm GaN LED, in which nearly fourfold light output power is achieved at 615 K (compared to 295 K room temperature operation), with nearly no reduction in the wall-plug efficiency (i.e., electrical-optical energy conversion efficiency) at bias V< ℏ ω/q. The LED is shown to work in a mode similar to a thermodynamic heat engine operating with charged carriers pumped into the active region by a combination of electrical work and Peltier heat (phonons) drawn from the lattice. In this optimal operating regime at 615 K, the LED injection current (3.26 A/cm[superscript 2]) is of similar magnitude to the operating point of common high power GaN based LEDs (5–35 A/cm[superscript 2]). This result suggests the possibility of removing bulky heat sinks in current high power LED products thus realizing a significant cost reduction for solid-state lighting.
MIT Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Massachusetts Institute of Technology. Research Laboratory of Electronics
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DOI of Published Version
https://doi.org/10.1063/1.4931365
