Novel evaluation procedure for internal and extraction efficiency of high-power blue LEDs

Ilya E. Titkov; Amit Yadav; Vera L. Zerova; Modestas Zulonas; Edik U. Rafailov; Sergey Yu. Karpov; Martin Strassburg; Ines Pietzonka; Hans-Juergen Lugauer; Bastian Galler

doi:10.1109/LO.2014.6886291

Novel evaluation procedure for internal and extraction efficiency of high-power blue LEDs

Ilya E. Titkov, Amit Yadav, Vera L. Zerova, Modestas Zulonas, Edik U. Rafailov, Sergey Yu. Karpov, Martin Strassburg, Ines Pietzonka, Hans-Juergen Lugauer, Bastian Galler

Aston Institute of Photonic Technologies (AiPT)

Research output: Chapter in Book/Published conference output › Conference publication

Abstract

Internal quantum efficiency (IQE) of a high-brightness blue LED has been evaluated from the external quantum efficiency measured as a function of current at room temperature. Processing the data with a novel evaluation procedure based on the ABC-model, we have determined separately IQE of the LED structure and light extraction efficiency (LEE) of UX:3 chip.

Full text

Nowadays, understanding of LED efficiency behavior at high currents is quite critical to find ways for further improvement of III-nitride LED performance [1]. External quantum efficiency η_e (EQE) provides integral information on the recombination and photon emission processes in LEDs. Meanwhile EQE is the product of IQE η_iand LEE η_ext at negligible carrier leakage from the active region. Separate determination of IQE and LEE would be much more helpful, providing correlation between these parameters and specific epi-structure and chip design. In this paper, we extend the approach of [2,3] to the whole range of the current/optical power variation, providing an express tool for separate evaluation of IQE and LEE.
We studied an InGaN-based LED fabricated by Osram OS. LED structure grown by MOCVD on sapphire substrate was processed as UX:3 chip and mounted into the Golden Dragon package without molding. EQE was measured with Labsphere CDS-600 spectrometer. Plotting EQE versus output power P and finding the power P_m corresponding to EQE maximum η_m enables comparing the measurements with the analytical relationships η_i= Q/(Q+p^1/2+p^-1/2) ,p = P/P_m , and Q = B/(AC) ^1/2 where A, Band C are recombination constants [4]. As a result, maximum IQE value equal to QI(Q+2) can be found from the ratio η_m/η_e plotted as a function of p^1/2+p1^-1/2 (see Fig.la) and then LEE calculated as η_ext = η_m (Q+2)/Q . Experimental EQE as a function of normalized optical power p is shown in Fig. 1 b along with the analytical approximation based on the ABCmodel. The approximation fits perfectly the measurements in the range of the optical power (or operating current) variation by eight orders of magnitude.
In conclusion, new express method for separate evaluation of IQE and LEE of III-nitride LEDs is suggested and applied to characterization of a high-brightness blue LED. With this method, we obtained LEE from the free chip surface to the air as 69.8% and IQE as 85.7% at the maximum and 65.2% at the operation current 350 rnA.

[I] G. Verzellesi, D. Saguatti, M. Meneghini, F. Bertazzi, M. Goano, G. Meneghesso, and E. Zanoni, "Efficiency droop in InGaN/GaN blue light-emitting diodes: Physical mechanisms and remedies," 1. AppL Phys., vol. 114, no. 7, pp. 071101, Aug., 2013.

[2] C. van Opdorp and G. W. 't Hooft, "Method for determining effective non radiative lifetime and leakage losses in double-heterostructure lasers," 1. AppL Phys., vol. 52, no. 6, pp. 3827-3839, Feb., 1981.

[3] M. Meneghini, N. Trivellin, G. Meneghesso, E. Zanoni, U. Zehnder, and B. Hahn, "A combined electro-optical method for the determination of the recombination parameters in InGaN-based light-emitting diodes," 1. AppL Phys., vol. 106, no. II, pp. 114508, Dec., 2009.

[4] Qi Dai, Qifeng Shan, ling Wang, S. Chhajed, laehee Cho, E. F. Schubert, M. H. Crawford, D. D. Koleske, Min-Ho Kim, and Yongjo Park, "Carrier recombination mechanisms and efficiency droop in GalnN/GaN light-emitting diodes," App/. Phys. Leu., vol. 97, no. 13, pp. 133507, Sept., 2010.

Original language	English
Title of host publication	Proceedings : 2014 international conference Laser Optics
Place of Publication	Piscataway, NJ (US)
Publisher	IEEE
Number of pages	1
ISBN (Electronic)	978-1-4799-3885-8
ISBN (Print)	978-1-4799-3884-1
DOIs	https://doi.org/10.1109/LO.2014.6886291 https://doi.org/10.1109/LO.2014.6886291
Publication status	Published - 31 Dec 2014
Event	2014 international conference Laser Optics - St. Petersburg, Russian Federation Duration: 30 Jun 2014 → 4 Jul 2014

Publication series

Name	2014 International Conference Laser Optics

Conference

Conference	2014 international conference Laser Optics
Abbreviated title	LO 2014
Country/Territory	Russian Federation
City	St. Petersburg
Period	30/06/14 → 4/07/14

Bibliographical note

© 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

Funding: European Union FP7, NEWLED project, Grant number 318388.

Keywords

III-nitrides
internal quantum efficiency
light extraction efficiency
light-emitting diodes

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Titkov, I. E., Yadav, A., Zerova, V. L., Zulonas, M., Rafailov, E. U., Karpov, S. Y., Strassburg, M., Pietzonka, I., Lugauer, H.-J., & Galler, B. (2014). Novel evaluation procedure for internal and extraction efficiency of high-power blue LEDs. In Proceedings : 2014 international conference Laser Optics (2014 International Conference Laser Optics). IEEE. https://doi.org/10.1109/LO.2014.6886291, https://doi.org/10.1109/LO.2014.6886291

@inproceedings{1dfcdcb2ef1147e383e94f184596c3b4,

title = "Novel evaluation procedure for internal and extraction efficiency of high-power blue LEDs",

abstract = "Internal quantum efficiency (IQE) of a high-brightness blue LED has been evaluated from the external quantum efficiency measured as a function of current at room temperature. Processing the data with a novel evaluation procedure based on the ABC-model, we have determined separately IQE of the LED structure and light extraction efficiency (LEE) of UX:3 chip. Full text Nowadays, understanding of LED efficiency behavior at high currents is quite critical to find ways for further improvement of III-nitride LED performance [1]. External quantum efficiency ηe (EQE) provides integral information on the recombination and photon emission processes in LEDs. Meanwhile EQE is the product of IQE ηi and LEE ηext at negligible carrier leakage from the active region. Separate determination of IQE and LEE would be much more helpful, providing correlation between these parameters and specific epi-structure and chip design. In this paper, we extend the approach of [2,3] to the whole range of the current/optical power variation, providing an express tool for separate evaluation of IQE and LEE. We studied an InGaN-based LED fabricated by Osram OS. LED structure grown by MOCVD on sapphire substrate was processed as UX:3 chip and mounted into the Golden Dragon package without molding. EQE was measured with Labsphere CDS-600 spectrometer. Plotting EQE versus output power P and finding the power Pm corresponding to EQE maximum ηm enables comparing the measurements with the analytical relationships ηi = Q/(Q+p1/2+p-1/2) ,p = P/Pm , and Q = B/(AC) 1/2 where A, Band C are recombination constants [4]. As a result, maximum IQE value equal to QI(Q+2) can be found from the ratio ηm/ηe plotted as a function of p1/2 +p1-1/2 (see Fig.la) and then LEE calculated as ηext = ηm (Q+2)/Q . Experimental EQE as a function of normalized optical power p is shown in Fig. 1 b along with the analytical approximation based on the ABCmodel. The approximation fits perfectly the measurements in the range of the optical power (or operating current) variation by eight orders of magnitude. In conclusion, new express method for separate evaluation of IQE and LEE of III-nitride LEDs is suggested and applied to characterization of a high-brightness blue LED. With this method, we obtained LEE from the free chip surface to the air as 69.8% and IQE as 85.7% at the maximum and 65.2% at the operation current 350 rnA. [I] G. Verzellesi, D. Saguatti, M. Meneghini, F. Bertazzi, M. Goano, G. Meneghesso, and E. Zanoni, {"}Efficiency droop in InGaN/GaN blue light-emitting diodes: Physical mechanisms and remedies,{"} 1. AppL Phys., vol. 114, no. 7, pp. 071101, Aug., 2013. [2] C. van Opdorp and G. W. 't Hooft, {"}Method for determining effective non radiative lifetime and leakage losses in double-heterostructure lasers,{"} 1. AppL Phys., vol. 52, no. 6, pp. 3827-3839, Feb., 1981. [3] M. Meneghini, N. Trivellin, G. Meneghesso, E. Zanoni, U. Zehnder, and B. Hahn, {"}A combined electro-optical method for the determination of the recombination parameters in InGaN-based light-emitting diodes,{"} 1. AppL Phys., vol. 106, no. II, pp. 114508, Dec., 2009. [4] Qi Dai, Qifeng Shan, ling Wang, S. Chhajed, laehee Cho, E. F. Schubert, M. H. Crawford, D. D. Koleske, Min-Ho Kim, and Yongjo Park, {"}Carrier recombination mechanisms and efficiency droop in GalnN/GaN light-emitting diodes,{"} App/. Phys. Leu., vol. 97, no. 13, pp. 133507, Sept., 2010. ",

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author = "Titkov, {Ilya E.} and Amit Yadav and Zerova, {Vera L.} and Modestas Zulonas and Rafailov, {Edik U.} and Karpov, {Sergey Yu.} and Martin Strassburg and Ines Pietzonka and Hans-Juergen Lugauer and Bastian Galler",

note = "{\textcopyright} 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. Funding: European Union FP7, NEWLED project, Grant number 318388.; 2014 international conference Laser Optics, LO 2014 ; Conference date: 30-06-2014 Through 04-07-2014",

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Titkov, IE, Yadav, A, Zerova, VL, Zulonas, M, Rafailov, EU, Karpov, SY, Strassburg, M, Pietzonka, I, Lugauer, H-J & Galler, B 2014, Novel evaluation procedure for internal and extraction efficiency of high-power blue LEDs. in Proceedings : 2014 international conference Laser Optics. 2014 International Conference Laser Optics, IEEE, Piscataway, NJ (US), 2014 international conference Laser Optics, St. Petersburg, Russian Federation, 30/06/14. https://doi.org/10.1109/LO.2014.6886291, https://doi.org/10.1109/LO.2014.6886291

TY - GEN

T1 - Novel evaluation procedure for internal and extraction efficiency of high-power blue LEDs

AU - Titkov, Ilya E.

AU - Yadav, Amit

AU - Zerova, Vera L.

AU - Zulonas, Modestas

AU - Rafailov, Edik U.

AU - Karpov, Sergey Yu.

AU - Strassburg, Martin

AU - Pietzonka, Ines

AU - Lugauer, Hans-Juergen

AU - Galler, Bastian

N1 - © 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. Funding: European Union FP7, NEWLED project, Grant number 318388.

PY - 2014/12/31

Y1 - 2014/12/31

N2 - Internal quantum efficiency (IQE) of a high-brightness blue LED has been evaluated from the external quantum efficiency measured as a function of current at room temperature. Processing the data with a novel evaluation procedure based on the ABC-model, we have determined separately IQE of the LED structure and light extraction efficiency (LEE) of UX:3 chip. Full text Nowadays, understanding of LED efficiency behavior at high currents is quite critical to find ways for further improvement of III-nitride LED performance [1]. External quantum efficiency ηe (EQE) provides integral information on the recombination and photon emission processes in LEDs. Meanwhile EQE is the product of IQE ηi and LEE ηext at negligible carrier leakage from the active region. Separate determination of IQE and LEE would be much more helpful, providing correlation between these parameters and specific epi-structure and chip design. In this paper, we extend the approach of [2,3] to the whole range of the current/optical power variation, providing an express tool for separate evaluation of IQE and LEE. We studied an InGaN-based LED fabricated by Osram OS. LED structure grown by MOCVD on sapphire substrate was processed as UX:3 chip and mounted into the Golden Dragon package without molding. EQE was measured with Labsphere CDS-600 spectrometer. Plotting EQE versus output power P and finding the power Pm corresponding to EQE maximum ηm enables comparing the measurements with the analytical relationships ηi = Q/(Q+p1/2+p-1/2) ,p = P/Pm , and Q = B/(AC) 1/2 where A, Band C are recombination constants [4]. As a result, maximum IQE value equal to QI(Q+2) can be found from the ratio ηm/ηe plotted as a function of p1/2 +p1-1/2 (see Fig.la) and then LEE calculated as ηext = ηm (Q+2)/Q . Experimental EQE as a function of normalized optical power p is shown in Fig. 1 b along with the analytical approximation based on the ABCmodel. The approximation fits perfectly the measurements in the range of the optical power (or operating current) variation by eight orders of magnitude. In conclusion, new express method for separate evaluation of IQE and LEE of III-nitride LEDs is suggested and applied to characterization of a high-brightness blue LED. With this method, we obtained LEE from the free chip surface to the air as 69.8% and IQE as 85.7% at the maximum and 65.2% at the operation current 350 rnA. [I] G. Verzellesi, D. Saguatti, M. Meneghini, F. Bertazzi, M. Goano, G. Meneghesso, and E. Zanoni, "Efficiency droop in InGaN/GaN blue light-emitting diodes: Physical mechanisms and remedies," 1. AppL Phys., vol. 114, no. 7, pp. 071101, Aug., 2013. [2] C. van Opdorp and G. W. 't Hooft, "Method for determining effective non radiative lifetime and leakage losses in double-heterostructure lasers," 1. AppL Phys., vol. 52, no. 6, pp. 3827-3839, Feb., 1981. [3] M. Meneghini, N. Trivellin, G. Meneghesso, E. Zanoni, U. Zehnder, and B. Hahn, "A combined electro-optical method for the determination of the recombination parameters in InGaN-based light-emitting diodes," 1. AppL Phys., vol. 106, no. II, pp. 114508, Dec., 2009. [4] Qi Dai, Qifeng Shan, ling Wang, S. Chhajed, laehee Cho, E. F. Schubert, M. H. Crawford, D. D. Koleske, Min-Ho Kim, and Yongjo Park, "Carrier recombination mechanisms and efficiency droop in GalnN/GaN light-emitting diodes," App/. Phys. Leu., vol. 97, no. 13, pp. 133507, Sept., 2010.

AB - Internal quantum efficiency (IQE) of a high-brightness blue LED has been evaluated from the external quantum efficiency measured as a function of current at room temperature. Processing the data with a novel evaluation procedure based on the ABC-model, we have determined separately IQE of the LED structure and light extraction efficiency (LEE) of UX:3 chip. Full text Nowadays, understanding of LED efficiency behavior at high currents is quite critical to find ways for further improvement of III-nitride LED performance [1]. External quantum efficiency ηe (EQE) provides integral information on the recombination and photon emission processes in LEDs. Meanwhile EQE is the product of IQE ηi and LEE ηext at negligible carrier leakage from the active region. Separate determination of IQE and LEE would be much more helpful, providing correlation between these parameters and specific epi-structure and chip design. In this paper, we extend the approach of [2,3] to the whole range of the current/optical power variation, providing an express tool for separate evaluation of IQE and LEE. We studied an InGaN-based LED fabricated by Osram OS. LED structure grown by MOCVD on sapphire substrate was processed as UX:3 chip and mounted into the Golden Dragon package without molding. EQE was measured with Labsphere CDS-600 spectrometer. Plotting EQE versus output power P and finding the power Pm corresponding to EQE maximum ηm enables comparing the measurements with the analytical relationships ηi = Q/(Q+p1/2+p-1/2) ,p = P/Pm , and Q = B/(AC) 1/2 where A, Band C are recombination constants [4]. As a result, maximum IQE value equal to QI(Q+2) can be found from the ratio ηm/ηe plotted as a function of p1/2 +p1-1/2 (see Fig.la) and then LEE calculated as ηext = ηm (Q+2)/Q . Experimental EQE as a function of normalized optical power p is shown in Fig. 1 b along with the analytical approximation based on the ABCmodel. The approximation fits perfectly the measurements in the range of the optical power (or operating current) variation by eight orders of magnitude. In conclusion, new express method for separate evaluation of IQE and LEE of III-nitride LEDs is suggested and applied to characterization of a high-brightness blue LED. With this method, we obtained LEE from the free chip surface to the air as 69.8% and IQE as 85.7% at the maximum and 65.2% at the operation current 350 rnA. [I] G. Verzellesi, D. Saguatti, M. Meneghini, F. Bertazzi, M. Goano, G. Meneghesso, and E. Zanoni, "Efficiency droop in InGaN/GaN blue light-emitting diodes: Physical mechanisms and remedies," 1. AppL Phys., vol. 114, no. 7, pp. 071101, Aug., 2013. [2] C. van Opdorp and G. W. 't Hooft, "Method for determining effective non radiative lifetime and leakage losses in double-heterostructure lasers," 1. AppL Phys., vol. 52, no. 6, pp. 3827-3839, Feb., 1981. [3] M. Meneghini, N. Trivellin, G. Meneghesso, E. Zanoni, U. Zehnder, and B. Hahn, "A combined electro-optical method for the determination of the recombination parameters in InGaN-based light-emitting diodes," 1. AppL Phys., vol. 106, no. II, pp. 114508, Dec., 2009. [4] Qi Dai, Qifeng Shan, ling Wang, S. Chhajed, laehee Cho, E. F. Schubert, M. H. Crawford, D. D. Koleske, Min-Ho Kim, and Yongjo Park, "Carrier recombination mechanisms and efficiency droop in GalnN/GaN light-emitting diodes," App/. Phys. Leu., vol. 97, no. 13, pp. 133507, Sept., 2010.

KW - III-nitrides

KW - internal quantum efficiency

KW - light extraction efficiency

KW - light-emitting diodes

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Novel evaluation procedure for internal and extraction efficiency of high-power blue LEDs

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