Increased effective reflection and transmission at the GaN-sapphire interface of LEDs grown on patterned sapphire substrates

Dongxue Wu; Ping Ma; Boting Liu; Shuo Zhang; Junxi Wang; Jinmin Li

doi:10.1088/1674-4926/37/10/104003

J. Semicond. > 2016, Volume 37 > Issue 10 > 104003

SEMICONDUCTOR DEVICES

Increased effective reflection and transmission at the GaN-sapphire interface of LEDs grown on patterned sapphire substrates

Dongxue Wu^{1, 2, 3}, Ping Ma^{1, 2, 3,}, Boting Liu^{1, 2, 3}, Shuo Zhang^{1, 2, 3}, Junxi Wang^{1, 2, 3} and Jinmin Li^{1, 2, 3}

+ Author Affiliations

Corresponding author: Ma Ping, maping@semi.ac.cn

DOI: 10.1088/1674-4926/37/10/104003

Abstract: The effect of patterned sapphire substrate (PSS) on the top-surface (P-GaN-surface) and the bottom-surface (sapphire-surface) of the light output power (LOP) of GaN-based LEDs was investigated, in order to study the changes in reflection and transmission of the GaN-sapphire interface. Experimental research and computer simulations were combined to reveal a great enhancement in LOP from either the top or bottom surface of GaN-based LEDs, which are prepared on patterned sapphire substrates (PSS-LEDs). Furthermore, the results were compared to those of the conventional LEDs prepared on the planar sapphire substrates (CSS-LEDs). A detailed theoretical analysis was also presented to further support the explanation for the increase in both the effective reflection and transmission of PSS-GaN interface layers and to explain the causes of increased LOP values. Moreover, the bottom-surface of the PSS-LED chip shows slightly increased light output performance when compared to that of the top-surface. Therefore, the light extraction efficiency (LEE) can be further enhanced by integrating the method of PSS and flip-chip structure design.

Key words: light output power, transmission, effective reflection, patterned sapphire substrate, light-emitting diodes

References

[1]	Wang L, Zhang Y, Li X, et al. Partially sandwiched graphene as transparent conductive layer for InGaN-based vertical light emitting diodes. Appl Phys Lett, 2012, 101(6): 061102 doi: 10.1063/1.4742892
[2]	Zhang Y, Wei T, Wang J, et al. The improvement of GaN-based light-emitting diodes using nanopatterned sapphire substrate with small pattern spacing. AIP Advances, 2014, 4(2): 027123 doi: 10.1063/1.4867091
[3]	Kim H G, Na M G, Kim H K, et al. Effect of periodic deflector embedded in InGaN/GaN light emitting diode. Appl Phys Lett, 2007, 90(26): 261117 doi: 10.1063/1.2752777
[4]	Lee Y J, Hsu T C, Kuo H C, et al. Improvement in light-output efficiency of near-ultraviolet InGaN-GaN LEDs fabricated on stripe patterned sapphire substrates. Mater Sci Eng B, 2005, 122(3): 184 doi: 10.1016/j.mseb.2005.05.019
[5]	Wu D S, Wang W K, Wen K S, et al. Defect reduction and efficiency improvement of near-ultraviolet emitters via laterally overgrown GaN on a GaN/patterned sapphire template. Appl Phys Lett, 2006, 89(16): 161105 doi: 10.1063/1.2363148
[6]	Cui H, Park S H. Numerical simulations of light-extraction efficiencies of light-emitting diodes on micro and nanopatterned sapphire substrates. Micro Nano Lett, 2014, 9(12): 841 doi: 10.1049/mnl.2014.0373
[7]	Du C, Wei T, Zheng H, et al. Size-controllable nanopyramids photonic crystal selectively grown on p-GaN for enhanced light-extraction of light-emitting diodes. Opt Express, 2013, 21(21): 25373 doi: 10.1364/OE.21.025373
[8]	Yamada M, Mitani T, Narukawa Y, et al. InGaN-based near-ultraviolet and blue-light-emitting diodes with high external quantum efficiency using a patterned sapphire substrate and a mesh electrode. Jpn J Appl Phys, 2002, 41(12B): L1431
[9]	Tadatomo K, Okagawa H, Ohuchi Y, et al. High output power near-ultraviolet and violet light-emitting diodes fabricated on patterned sapphire substrates using metalorganic vapor phase epitaxy. Third International Conference on Solid State Lighting, 2004: 243
[10]	Wang C C, Ku H, Liu C C, et al. Enhancement of the light output performance for GaN-based light-emitting diodes by bottom pillar structure. Appl Phys Lett, 2007, 91(12): 121109 doi: 10.1063/1.2786015
[11]	Gao H, Yan F, Zhang Y, et al. Enhancement of the light output power of InGaN/GaN light-emitting diodes grown on pyramidal patterned sapphire substrates in the micro-and nanoscale. J Appl Phys, 2008, 103(1): 014314 doi: 10.1063/1.2830981
[12]	Cuong T V, Cheong H S, Kim H G, et al. Enhanced light output from aligned micropit InGaN-based light emitting diodes using wet-etch sapphire patterning. Appl Phys Lett, 2007, 90(13): 131107 doi: 10.1063/1.2714203
[13]	An Tielei, Sun Bo, Wei Tongbo, et al. Light-extraction enhancement of freestanding GaN-based flip-chip light-emitting diodes using two-step roughening methods. Journal of Semiconductors, 2013, 34(11): 114006 doi: 10.1088/1674-4926/34/11/114006
[14]	Pan J W, Tsai P J, Chang K D, et al. Light extraction efficiency analysis of GaN-based light-emitting diodes with nanopatterned sapphire substrates. Appl Opt, 2013, 52(7): 1358 doi: 10.1364/AO.52.001358
[15]	Lee J H, Oh J T, Kim Y C, et al. Stress reduction and enhanced extraction efficiency of GaN-based LED grown on cone-shape-patterned sapphire. IEEE Photon Technol Lett, 2008, 20(17-20): 1563
[16]	Skaar J. Fresnel equations and the refractive index of active media. Phys Rev E, 2006, 73(2): 026605 doi: 10.1103/PhysRevE.73.026605
[17]	Ding Q A, Li K, Kong F, et al. Improving the vertical light extraction efficiency of GaN-based thin-film flip-chip LED with double embedded photonic crystals. IEEE J Quantum Electron, 2015, 51(2): 1
[18]	Lee Y J, Kuo H C, Lu T C, et al. Fabrication and characterization of GaN-based LEDs grown on chemical wet-etched patterned sapphire substrates. J Electrochem Soc, 2006, 153(12): G1106 doi: 10.1149/1.2359701
[19]	Lee T X, Lin C Y, Ma S H, et al. Analysis of position-dependent light extraction of GaN-based LEDs. Opt Express, 2005, 13(11): 4175 doi: 10.1364/OPEX.13.004175
[20]	Chen Maoxing, Xu Chen, Xu Kun, et al. Thermal simulation and analysis of flat surface flip-chip high power light-emitting diodes. Journal of Semiconductors, 2013, 34(12): 124005 doi: 10.1088/1674-4926/34/12/124005

Fig. 1. (Color online) Schematic illustration of Trace-Pro simulation models: (a) PSS-LED, (b) CSS-LED. 151

$\times$ 91 mm

$^{2}$ (96

$\times$ 96 DPI

$^{2}$ ).

DownLoad: Full-Size Img PowerPoint

Fig. 2. Cross-sectional SEM images of patterns. 127

$\times$ 95 mm (256

$\times$ 256 DPI

$^{2}$ ).

DownLoad: Full-Size Img PowerPoint

Fig. 3. (Color online) The top and bottom light output power as a function of the injection current for LEDs grown on PSS and CSS.

DownLoad: Full-Size Img PowerPoint

Fig. 4. A schematic of the possible interactions of a beam of light with a surface with different refractive indexes. 143

$\times$ 112 mm

$^{2}$ (96

$\times$ 96 DPI

$^{2}$ ).

DownLoad: Full-Size Img PowerPoint

Fig. 5. Reflection coefficient as a function of the incident angle of

$\theta_{\rm i}$ :

$R$ -

$\theta_{\rm i}$ curve. 252

$\times$ 163 mm

$^{2}$ (96

$\times$ 96 DPI

$^{2}$ ).

DownLoad: Full-Size Img PowerPoint

Fig. 6. A schematic ray-tracing of light. 254

$\times$ 190 mm (96

$\times$ 96 DPI).

DownLoad: Full-Size Img PowerPoint

Table 1. The absorbed power by various monitors.

[1]	Wang L, Zhang Y, Li X, et al. Partially sandwiched graphene as transparent conductive layer for InGaN-based vertical light emitting diodes. Appl Phys Lett, 2012, 101(6): 061102 doi: 10.1063/1.4742892
[2]	Zhang Y, Wei T, Wang J, et al. The improvement of GaN-based light-emitting diodes using nanopatterned sapphire substrate with small pattern spacing. AIP Advances, 2014, 4(2): 027123 doi: 10.1063/1.4867091
[3]	Kim H G, Na M G, Kim H K, et al. Effect of periodic deflector embedded in InGaN/GaN light emitting diode. Appl Phys Lett, 2007, 90(26): 261117 doi: 10.1063/1.2752777
[4]	Lee Y J, Hsu T C, Kuo H C, et al. Improvement in light-output efficiency of near-ultraviolet InGaN-GaN LEDs fabricated on stripe patterned sapphire substrates. Mater Sci Eng B, 2005, 122(3): 184 doi: 10.1016/j.mseb.2005.05.019
[5]	Wu D S, Wang W K, Wen K S, et al. Defect reduction and efficiency improvement of near-ultraviolet emitters via laterally overgrown GaN on a GaN/patterned sapphire template. Appl Phys Lett, 2006, 89(16): 161105 doi: 10.1063/1.2363148
[6]	Cui H, Park S H. Numerical simulations of light-extraction efficiencies of light-emitting diodes on micro and nanopatterned sapphire substrates. Micro Nano Lett, 2014, 9(12): 841 doi: 10.1049/mnl.2014.0373
[7]	Du C, Wei T, Zheng H, et al. Size-controllable nanopyramids photonic crystal selectively grown on p-GaN for enhanced light-extraction of light-emitting diodes. Opt Express, 2013, 21(21): 25373 doi: 10.1364/OE.21.025373
[8]	Yamada M, Mitani T, Narukawa Y, et al. InGaN-based near-ultraviolet and blue-light-emitting diodes with high external quantum efficiency using a patterned sapphire substrate and a mesh electrode. Jpn J Appl Phys, 2002, 41(12B): L1431
[9]	Tadatomo K, Okagawa H, Ohuchi Y, et al. High output power near-ultraviolet and violet light-emitting diodes fabricated on patterned sapphire substrates using metalorganic vapor phase epitaxy. Third International Conference on Solid State Lighting, 2004: 243
[10]	Wang C C, Ku H, Liu C C, et al. Enhancement of the light output performance for GaN-based light-emitting diodes by bottom pillar structure. Appl Phys Lett, 2007, 91(12): 121109 doi: 10.1063/1.2786015
[11]	Gao H, Yan F, Zhang Y, et al. Enhancement of the light output power of InGaN/GaN light-emitting diodes grown on pyramidal patterned sapphire substrates in the micro-and nanoscale. J Appl Phys, 2008, 103(1): 014314 doi: 10.1063/1.2830981
[12]	Cuong T V, Cheong H S, Kim H G, et al. Enhanced light output from aligned micropit InGaN-based light emitting diodes using wet-etch sapphire patterning. Appl Phys Lett, 2007, 90(13): 131107 doi: 10.1063/1.2714203
[13]	An Tielei, Sun Bo, Wei Tongbo, et al. Light-extraction enhancement of freestanding GaN-based flip-chip light-emitting diodes using two-step roughening methods. Journal of Semiconductors, 2013, 34(11): 114006 doi: 10.1088/1674-4926/34/11/114006
[14]	Pan J W, Tsai P J, Chang K D, et al. Light extraction efficiency analysis of GaN-based light-emitting diodes with nanopatterned sapphire substrates. Appl Opt, 2013, 52(7): 1358 doi: 10.1364/AO.52.001358
[15]	Lee J H, Oh J T, Kim Y C, et al. Stress reduction and enhanced extraction efficiency of GaN-based LED grown on cone-shape-patterned sapphire. IEEE Photon Technol Lett, 2008, 20(17-20): 1563
[16]	Skaar J. Fresnel equations and the refractive index of active media. Phys Rev E, 2006, 73(2): 026605 doi: 10.1103/PhysRevE.73.026605
[17]	Ding Q A, Li K, Kong F, et al. Improving the vertical light extraction efficiency of GaN-based thin-film flip-chip LED with double embedded photonic crystals. IEEE J Quantum Electron, 2015, 51(2): 1
[18]	Lee Y J, Kuo H C, Lu T C, et al. Fabrication and characterization of GaN-based LEDs grown on chemical wet-etched patterned sapphire substrates. J Electrochem Soc, 2006, 153(12): G1106 doi: 10.1149/1.2359701
[19]	Lee T X, Lin C Y, Ma S H, et al. Analysis of position-dependent light extraction of GaN-based LEDs. Opt Express, 2005, 13(11): 4175 doi: 10.1364/OPEX.13.004175
[20]	Chen Maoxing, Xu Chen, Xu Kun, et al. Thermal simulation and analysis of flat surface flip-chip high power light-emitting diodes. Journal of Semiconductors, 2013, 34(12): 124005 doi: 10.1088/1674-4926/34/12/124005

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D X Wu, P Ma, B T Liu, S Zhang, J X Wang, J M Li. Increased effective reflection and transmission at the GaN-sapphire interface of LEDs grown on patterned sapphire substrates[J]. J. Semicond., 2016, 37(10): 104003. doi: 10.1088/1674-4926/37/10/104003.

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Received: 28 January 2016 Revised: 15 April 2016 Online: Published: 01 October 2016

Article Navigation > Journal of Semiconductors > 2016 > 37(10): 104003

Dongxue Wu, Ping Ma, Boting Liu, Shuo Zhang, Junxi Wang, Jinmin Li. Increased effective reflection and transmission at the GaN-sapphire interface of LEDs grown on patterned sapphire substrates[J]. Journal of Semiconductors, 2016, 37(10): 104003. doi: 10.1088/1674-4926/37/10/104003 ****D X Wu, P Ma, B T Liu, S Zhang, J X Wang, J M Li. Increased effective reflection and transmission at the GaN-sapphire interface of LEDs grown on patterned sapphire substrates[J]. J. Semicond., 2016, 37(10): 104003. doi: 10.1088/1674-4926/37/10/104003.

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Increased effective reflection and transmission at the GaN-sapphire interface of LEDs grown on patterned sapphire substrates

DOI: 10.1088/1674-4926/37/10/104003

Dongxue Wu^1,2,3,
Ping Ma^1,2,3,,
Boting Liu^1,2,3,
Shuo Zhang^1,2,3,
Junxi Wang^1,2,3,
Jinmin Li^1,2,3

1.
Research and Development Center for Solid State Lighting, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
2.
State Key Laboratory of Solid State Lighting, Beijing 100083, China
3.
Beijing Engineering Research Center for the 3rd Generation Semiconductor Materials and Application, Beijing 100083, China

Funds:

Project supported by the National High Technology Program of China (No.Y48A040000) and the National High Technology Program of China (No.Y48A040000)

the National High Technology Program of China Y48A040000

More Information

Corresponding author: Ma Ping, maping@semi.ac.cn
Received Date: 2016-01-28
Revised Date: 2016-04-15
Published Date: 2016-10-01

Abstract

Abstract

The effect of patterned sapphire substrate (PSS) on the top-surface (P-GaN-surface) and the bottom-surface (sapphire-surface) of the light output power (LOP) of GaN-based LEDs was investigated, in order to study the changes in reflection and transmission of the GaN-sapphire interface. Experimental research and computer simulations were combined to reveal a great enhancement in LOP from either the top or bottom surface of GaN-based LEDs, which are prepared on patterned sapphire substrates (PSS-LEDs). Furthermore, the results were compared to those of the conventional LEDs prepared on the planar sapphire substrates (CSS-LEDs). A detailed theoretical analysis was also presented to further support the explanation for the increase in both the effective reflection and transmission of PSS-GaN interface layers and to explain the causes of increased LOP values. Moreover, the bottom-surface of the PSS-LED chip shows slightly increased light output performance when compared to that of the top-surface. Therefore, the light extraction efficiency (LEE) can be further enhanced by integrating the method of PSS and flip-chip structure design.
- light output power,
- transmission,
- effective reflection,
- patterned sapphire substrate,
- light-emitting diodes

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References(20)

References

[1]	Wang L, Zhang Y, Li X, et al. Partially sandwiched graphene as transparent conductive layer for InGaN-based vertical light emitting diodes. Appl Phys Lett, 2012, 101(6): 061102 doi: 10.1063/1.4742892
[2]	Zhang Y, Wei T, Wang J, et al. The improvement of GaN-based light-emitting diodes using nanopatterned sapphire substrate with small pattern spacing. AIP Advances, 2014, 4(2): 027123 doi: 10.1063/1.4867091
[3]	Kim H G, Na M G, Kim H K, et al. Effect of periodic deflector embedded in InGaN/GaN light emitting diode. Appl Phys Lett, 2007, 90(26): 261117 doi: 10.1063/1.2752777
[4]	Lee Y J, Hsu T C, Kuo H C, et al. Improvement in light-output efficiency of near-ultraviolet InGaN-GaN LEDs fabricated on stripe patterned sapphire substrates. Mater Sci Eng B, 2005, 122(3): 184 doi: 10.1016/j.mseb.2005.05.019
[5]	Wu D S, Wang W K, Wen K S, et al. Defect reduction and efficiency improvement of near-ultraviolet emitters via laterally overgrown GaN on a GaN/patterned sapphire template. Appl Phys Lett, 2006, 89(16): 161105 doi: 10.1063/1.2363148
[6]	Cui H, Park S H. Numerical simulations of light-extraction efficiencies of light-emitting diodes on micro and nanopatterned sapphire substrates. Micro Nano Lett, 2014, 9(12): 841 doi: 10.1049/mnl.2014.0373
[7]	Du C, Wei T, Zheng H, et al. Size-controllable nanopyramids photonic crystal selectively grown on p-GaN for enhanced light-extraction of light-emitting diodes. Opt Express, 2013, 21(21): 25373 doi: 10.1364/OE.21.025373
[8]	Yamada M, Mitani T, Narukawa Y, et al. InGaN-based near-ultraviolet and blue-light-emitting diodes with high external quantum efficiency using a patterned sapphire substrate and a mesh electrode. Jpn J Appl Phys, 2002, 41(12B): L1431
[9]	Tadatomo K, Okagawa H, Ohuchi Y, et al. High output power near-ultraviolet and violet light-emitting diodes fabricated on patterned sapphire substrates using metalorganic vapor phase epitaxy. Third International Conference on Solid State Lighting, 2004: 243
[10]	Wang C C, Ku H, Liu C C, et al. Enhancement of the light output performance for GaN-based light-emitting diodes by bottom pillar structure. Appl Phys Lett, 2007, 91(12): 121109 doi: 10.1063/1.2786015
[11]	Gao H, Yan F, Zhang Y, et al. Enhancement of the light output power of InGaN/GaN light-emitting diodes grown on pyramidal patterned sapphire substrates in the micro-and nanoscale. J Appl Phys, 2008, 103(1): 014314 doi: 10.1063/1.2830981
[12]	Cuong T V, Cheong H S, Kim H G, et al. Enhanced light output from aligned micropit InGaN-based light emitting diodes using wet-etch sapphire patterning. Appl Phys Lett, 2007, 90(13): 131107 doi: 10.1063/1.2714203
[13]	An Tielei, Sun Bo, Wei Tongbo, et al. Light-extraction enhancement of freestanding GaN-based flip-chip light-emitting diodes using two-step roughening methods. Journal of Semiconductors, 2013, 34(11): 114006 doi: 10.1088/1674-4926/34/11/114006
[14]	Pan J W, Tsai P J, Chang K D, et al. Light extraction efficiency analysis of GaN-based light-emitting diodes with nanopatterned sapphire substrates. Appl Opt, 2013, 52(7): 1358 doi: 10.1364/AO.52.001358
[15]	Lee J H, Oh J T, Kim Y C, et al. Stress reduction and enhanced extraction efficiency of GaN-based LED grown on cone-shape-patterned sapphire. IEEE Photon Technol Lett, 2008, 20(17-20): 1563
[16]	Skaar J. Fresnel equations and the refractive index of active media. Phys Rev E, 2006, 73(2): 026605 doi: 10.1103/PhysRevE.73.026605
[17]	Ding Q A, Li K, Kong F, et al. Improving the vertical light extraction efficiency of GaN-based thin-film flip-chip LED with double embedded photonic crystals. IEEE J Quantum Electron, 2015, 51(2): 1
[18]	Lee Y J, Kuo H C, Lu T C, et al. Fabrication and characterization of GaN-based LEDs grown on chemical wet-etched patterned sapphire substrates. J Electrochem Soc, 2006, 153(12): G1106 doi: 10.1149/1.2359701
[19]	Lee T X, Lin C Y, Ma S H, et al. Analysis of position-dependent light extraction of GaN-based LEDs. Opt Express, 2005, 13(11): 4175 doi: 10.1364/OPEX.13.004175
[20]	Chen Maoxing, Xu Chen, Xu Kun, et al. Thermal simulation and analysis of flat surface flip-chip high power light-emitting diodes. Journal of Semiconductors, 2013, 34(12): 124005 doi: 10.1088/1674-4926/34/12/124005

Increased effective reflection and transmission at the GaN-sapphire interface of LEDs grown on patterned sapphire substrates

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Increased effective reflection and transmission at the GaN-sapphire interface of LEDs grown on patterned sapphire substrates

DOI: 10.1088/1674-4926/37/10/104003

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Increased effective reflection and transmission at the GaN-sapphire interface of LEDs grown on patterned sapphire substrates

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Increased effective reflection and transmission at the GaN-sapphire interface of LEDs grown on patterned sapphire substrates

DOI: 10.1088/1674-4926/37/10/104003

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