Thermally enhanced blue light-emitting diode

Jin Xue, Yuji Zhao, Sang Ho Oh, William F. Herrington, James S. Speck, Steven P. DenBaars, Shuji Nakamura, Rajeev J. Ram

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


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< 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/cm2) is of similar magnitude to the operating point of common high power GaN based LEDs (5-35 A/cm2). 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.

Original languageEnglish (US)
Article number121109
JournalApplied Physics Letters
Issue number12
StatePublished - Sep 21 2015
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)


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