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Low temperature studies of the efficiency droop in InGaN-based light-emitting diodes

Title
Low temperature studies of the efficiency droop in InGaN-based light-emitting diodes
Author
신동수
Keywords
efficiency droop; electroluminescence; internal quantum efficiency; low temperature; nonradiative recombination; open-circuit voltage; photoluminescence; saturation of radiative recombination rate
Issue Date
2014-03
Publisher
International Society for Optical Engineering; 1999
Citation
PROCEEDINGS - SPIE THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING, Vol.8986 No.- [2014], pp. 8986 1S
Abstract
The efficiency droop in light-emitting diodes (LEDs) represents a gradual decrease of the internal quantum efficiency (IQE) with increasing current. Experimentally, the IQE droops are strong functions of material, epitaxial and chip structures, and operating temperature. Recently, we have proposed an IQE droop model as the saturation of the radiative recombination rate at low current and subsequent increase in the nonradiative recombination rates at high current. Once the radiative recombination rate begins to saturate at an active region, the carrier density as well as the nonradiative recombination rate rapidly increase there. Eventually, the IQE droop appears from the increase in the nonradiative recombination rate being much larger than that in the radiative one. A dominant nonradiative recombination process is not solely determined for each LED chip, but it could vary with current level and operating temperature. As temperature decreases, in general, the IQE droop becomes larger with the peak IQE occurring at an extremely small current level. We test the droop model by investigating the radiative and nonradiative recombination processes separately from the cryogenic to room temperature. The characterization methods include comparative efficiency study between photoluminescence (PL) and electroluminescence (EL), open-circuit voltage under resonant PL excitation, interrelations of current-voltage-light characteristics, and EL spectra of color-coded quantum wells (QWs). Although a sudden increase of the nonradiative recombination rate is an apparent cause of the IQE droop, the saturation of the radiative recombination rate is the common trigger behind the IQE droop issue.ⓒ (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
URI
http://www.spiedigitallibrary.org/conference-proceedings-of-spie/8986/1/Low-temperature-studies-of-the-efficiency-droop-in-InGaN-based/10.1117/12.2037986.full?SSO=1http://hdl.handle.net/20.500.11754/50379
ISBN
978-081949899-1
ISSN
0277-786X
DOI
10.1117/12.2037986
Appears in Collections:
GRADUATE SCHOOL[S](대학원) > BIONANOTECHNOLOGY(바이오나노학과) > Articles
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