Open AccessHigh wall-plug efficiency blue III-nitride LEDs designed for low current density operation
Author(s) -
Leah Y. Kuritzky,
Andrew Espenlaub,
Benjamin P. Yonkee,
Christopher D. Pynn,
Steven P. DenBaars,
Shuji Nakamura,
C. Weisbuch,
James S. Speck
Publication year - 2017
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.25.030696
Subject(s) - voltage droop , light emitting diode , materials science , optoelectronics , voltage , current (fluid) , current density , low voltage , optics , electrical engineering , physics , voltage source , engineering , quantum mechanics
Commercial LEDs for solid-state lighting are often designed for operation at current densities in the droop regime (~35 A/cm 2 ) to minimize costly chip area; however, many benefits can be realized by operating at low current density (J ≈1 - 5 A/cm 2 ). Along with mitigation of droop losses and reduction of the operating voltage, low J operation of LEDs opens the design space for high light extraction efficiency (LEE). This work presents detailed ray tracing simulations of an LED design for low J operation with LEE ≈94%. The design is realized experimentally resulting in a peak wall-plug efficiency of 78.1% occurring at 3.45 A/cm 2 and producing an output power of 7.2 mW for a 0.1 mm 2 emitting area. At this operation point, the photon voltage V p =hνq exceeds the forward voltage (V), corresponding to a Vp/V = 103%.