Efficieny Droop Solution for High Power Nitride LEDs



One of the most important issues in InGaN quantum well LEDs in the reduction in efficiency at high current density, which is referred to as “efficiency-droop.” Various explanations for this include carrier leakage, auger recombination and decreased carrier localization at in-rich regions, hole transport, and junctions hearting. However, the issued remain very controversial.

In this invention by Lehigh University, the current injection efficiency and internal quantum efficiency of InGaN QWs are investigated. To suppress the efficiency-droop, novel QW-barrier designs with significant suppressions of thermionic carrier escape at high current density are required. The significant reduction of current injection efficiency is observed, which leads to efficiency-droop. The use of thin low Al-content AlGaN barriers leads to slight reduction in quenching of the current injection efficiency. Additionally, the use of thin latticed-matched AllnN barriers shows significant reduction in efficiency-droop, which provides a possible solution for the efficiency droop issue in nitride LEDs.


Lehigh Tech ID# 112009-02



The SSL market is predicted to reach $33 billion by 2013, growing annually at over 10%.[1] This market is an umbrella market for LEDs, OLEDs, and PLEDs. LED technologies make up a majority of this market ($5.08 billion), with a growth rate of over 24%.[2] Additionally, 22% of the United States electricity is consumed by lighting, which costs consumers over $50 billion each year. SSL technologies have the potential to reduce this consumption by up to six times less. This potential has led to increased market need, funding resources and science centers dedicated to SSL developments, such as the $46 million Energy Frontier Research Center (EFRC) for solid-state lighting science funded by the Department of Energy.[3]


[1] “Solid-State Lighting Market Will Reach $33 Billion Worldwide by 2013.” AZooptics.com web site. http://www.azooptics.com/Details.asp?NewsID=3867 (accessed September 28, 2010).

[2] About Us.” GE Lumination web site. http://www.lumination.com/overview.php (accessed September 28, 2010).

[3] Solid-state lighting's contributions to national energy efficiency discussed at AAAS meeting.” February 21, 2010. PHYSORG web site. http://www.physorg.com/news185943042.html (accessed

September 28, 2010).



Lehigh University is interested in identifying an industry partner to license this technology. 

App Type Country Serial No. Patent No. File Date Issued Date Expire Date
Utility United States 12/967,367 8,907,321 12/14/2010 12/9/2014 7/15/2032
Energy and Environment
For Information, Contact:
Yatin Karpe
Associate Director
Lehigh University
Nelson Tansu
Hongping Zhao
Guangyu Liu
Ronald Arif