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Chin. Phys. B, 2019, Vol. 28(1): 017203    DOI: 10.1088/1674-1056/28/1/017203

Current diffusion and efficiency droop in vertical light emitting diodes

R Q Wan(万荣桥)1, T Li(李滔)1, Z Q Liu(刘志强)2,3, X Y Yi(伊晓燕)2,3, J X Wang(王军喜)2,3, J H Li(李军辉)1, W H Zhu(朱文辉)1, J M Li(李晋闽)2, L C Wang(汪炼成)1
1 State Key Laboratory of High Performance Complex Manufacturing, College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China;
2 Semiconductor Lighting Technology Research and Development Center, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China;
3 College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 101408, China

Current diffusion is an old issue, nevertheless, the relationship between the current diffusion and the efficiency of light emitting diodes (LEDs) needs to be further quantitatively clarified. By incorporating current crowding effect (CCE) into the conventional ABC model, we have theoretically and directly correlated the current diffusion and the internal quantum efficiency (IQE), light extraction efficiency (LEE), and external quantum efficiency (EQE) droop of the lateral LEDs. However, questions still exist for the vertical LEDs (V-LEDs). Here firstly the current diffusion length Ls(I) and Ls(Ⅱ) have been clarified. Based on this, the influence of CCE on the EQE, IQE, and LEE of V-LEDs were investigated. Specifically to our V-LEDs with moderate series resistivity, Ls(Ⅲ) was developed by combining Ls(I) and Ls(Ⅱ), and the CCE effect on the performance of V-LEDs was investigated. The wall-plug efficiency (WPE) of V-LEDs ware investigated finally. Our works provide a deep understanding of the current diffusion status and the correlated efficiency droop in V-LEDs, thus would benefit the V-LEDs' chip design and further efficiency improvement.

Keywords:  efficiency droop      vertical light emitting diodes      current crowding effect      current blocking layer  
Received:  21 June 2018      Revised:  07 November 2018      Published:  05 January 2019
PACS:  72.90.+y (Other topics in electronic transport in condensed matter)  

Project supported by the National Key Research and Development Program of China (Grant No. 2018YFB0406702), the Professorship Start-up Funding (Grant No. 217056), the Innovation-Driven Project of Central South University, China (Grant No. 2018CX001), the Project of State Key Laboratory of High-Performance Complex Manufacturing, Central South University, China (Grant No. ZZYJKT2018-01), and Guangzhou Science & Technology Project of Guangdong Province, China (Grant Nos. 201704030106 and 2016201604030035).

Corresponding Authors:  L C Wang     E-mail:,

Cite this article: 

R Q Wan(万荣桥), T Li(李滔), Z Q Liu(刘志强), X Y Yi(伊晓燕), J X Wang(王军喜), J H Li(李军辉), W H Zhu(朱文辉), J M Li(李晋闽), L C Wang(汪炼成) Current diffusion and efficiency droop in vertical light emitting diodes 2019 Chin. Phys. B 28 017203

[1] Zhao Y K, Li Y F, Huang Y P, Wang H, Su X L, Ding W and Yun F 2015 Chin. Phys. B 24 056806
[2] Zhuo X J, Zhang J, Li D W, Yi H X, Ren Z W, Tong J H, Wang X F, Chen X, Zhao B J, Wang W L and Li S T 2014 Chin. Phys. B 23 068502
[3] Yang B, Guo Z Y, Xie N, Zhang P J, Li J, Li F Z, Lin H, Zheng H and Cai J X 2014 Chin. Phys. B 23 048502
[4] Thompson G H B 1980 Physics of Semiconductor Laser Devices (New York: John Wiley and Sons)
[5] Guo X and Schubert E 2001 J. Appl. Phys. 90 4191
[6] Guo X and Schubert E 2001 Appl. Phys. Lett. 78 3337
[7] Schubert E F, Gessmann T and Kim J K 2005 Light Emitting Diodes (New York: John Wiley and Sons)
[8] Joyce W 1970 J. Appl. Phys. 41 3818
[9] Rattier M, Benisty H, Stanley R, Carlin J, Houdre R, Oesterle U, Smith C, Weisbuch C and Krauss T 2002 IEEE J. Select. Top. Quantum Electron. 8 238
[10] Chernyakov A, Bulashevich K, Karpov S and Zakgeim A 2013 Phys. Status Solidi A 210 466
[11] Calciati M, Goano M, Bertazzi F, Vallone M, Zhou X, Ghione G, Meneghini M, Meneghesso G, Zanoni E, Bellotti E, Verzellesi G, Zhu D and Humphreys C 2014 AIP Adv. 4 067118
[12] Huang S, Fan B, Chen Z, Zheng Z, Luo H, Wu Z, Wang G and Jiang H 2013 J. Display Technol. 9 266
[13] Ebong A, Arthur S, Downey E, Cao X, LeBoeuf S and Merfeld D 2003 Solid-State Electron. 47 1817
[14] Cao B, Li S, Hu R, Zhou S, Sun Y, Gan Z and Liu S 2013 Opt. Express 21 25381
[15] Li C and Wu Y 2012 IEEE Trans. Electron. Devices 59 400
[16] Zhang Y, Zheng H, Guo E, Cheng Y, Ma J, Wang L, Liu Z, Yi X, Wang G and Li J 2013 J. Appl. Phys. 113 014502
[17] Lee H, Pan K, Lin C, Chang Y, Kao F and Lee C 2007 J. Vac. Sci. Technol. B 25 1280
[18] Kim H, Lee J, Huh C, Kim S, Kim D, Park S and Hwang H 2000 Appl. Phys. Lett. 77 1903
[19] Kim H, Park S, Hwang H and Park N 2002 Appl. Phys. Lett. 81 1326
[20] Kim H, Park S J and Hwang H 2001 IEEE Trans. Electron. Dev. 48 1065
[21] Bogdanov M, Bulashevich K, Evstratov I, Zhmakin A and Karpov S 2008 Semicond. Sci. Technol. 23 125023
[22] Guo X, Li Y and Schubert E 2001 Appl. Phys. Lett. 79 1936
[23] Wang L, Liu W, Zhang Y, Zhang Z, Tan S, Yi X, Wang G, Sun X, Zhu H and Demir H 2015 Nano Energy 12 419
[24] Wang L, Zhang Y, Li X, Liu Z, Guo E, Yi X, Wang J, Zhu H and Wang G 2012 Appl. Phys. Lett. 101 061102
[25] Zhang Y, Wei T, Xiong Z, Chen Y, Zhen A, Shan L, Zhao Y, Hu Q, Li J and Wang J 2014 J. Appl. Phys. 116 194301
[26] Zhang Y, Li J, Wei T, Liu J, Yi X, Wang G and Yi F 2012 Jpn. J. Appl. Phys. 51 020204
[27] Jeon S, Song Y, Jang H, Yang G, Hwang S and Son S 2001 Appl. Phys. Lett. 78 3265
[28] Zhang Z, Tan S, Kyaw Z, Ji Y, Liu W, Ju Z, Hasanov N, Sun X and Demir H 2013 Appl. Phys. Lett. 102 193508
[29] Huh C, Lee J, Kim D and Park S 2002 J. Appl. Phys. 92 2248
[30] Malyutenko V, Bolgov S and Podoltsev A 2010 Appl. Phys. Lett. 97 251110
[31] Piprek J 2010 Phys. Stat. Sol. 207 2217
[32] Wang L, Zhang Z and Wang N 2015 IEEE J. Quantum Electron. 51 3200109
[33] Ryu H and Shim J 2011 Opt. Express 19 2886
[34] Wang L, Liu Z, Guo E, Yang H, Yi X and Wang G 2013 ACS Appl. Mater &Interfaces 5 5797
[35] Wang L, Zhang Y, Li X, Liu Z, Guo E, Yi X, Wang J, Zhu H and Wang G 2012 J. Phys. D: Appl. Phys. 45 505102
[36] Zhu D, Xu J, Noemaun A, Kim J, Schubert E, Crawford M and Koleske D 2009 Appl. Phys. Lett. 94 081113
[37] Wang L, Zhang Y, Li X, Liu Z, Zhang L, Guo E, Yi X, Zhu H and Wang G 2013 Proc. Roy. Soc. London A: Math. Phys. Eng. Sci. 469 20120652
[38] Wang L, Guo E, Liu Z, Yi X and Wang G 2016 IEEE Trans. Electron. Dev. 63 892
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