Research on Anodic Aluminum Oxide Nanostructured LEDs

doi:10.15541/jim20190246

Abstract

Abstract:

LED has the advantages of high efficiency, energy saving and environmental protection. It is widely used in the field of lighting. Improving the luminous efficiency of LED has always been a research difficulty and hot spot in this field. To reduce the total reflection phenomenon between GaN material and air and to improve the light extraction efficiency, fabrication and properties of the anodized aluminum oxide (AAO) nanostructured LED device were studied. Through inductively coupled plasma (ICP) etching process, large-area ordered pore nanostructure arrays were successfully fabricated on the surface of p-GaN layer, and the quasi-photonic crystal structure with apertures of 250-500 nm and pore depths of 50-150 nm were obtained. The crystal structure greatly increases the luminous intensity of the LED, and the nano-array LED with pore diameter of 400 nm and depth of 150 nm is improved by 3.5 times in contrast to the LED without the nano-array.

Key words: inductively coupled plasma etching, GaN, LED, quasi-photonic crystal, anodic aluminum oxide membrane

CLC Number:

TN383

ZHENG Xue, JIANG Rui, LI Qian, WANG Weizhe, XU Zhimou, PENG Jing. Research on Anodic Aluminum Oxide Nanostructured LEDs[J]. Journal of Inorganic Materials, 2020, 35(5): 561-566.

Figures/Tables 7

Fig. 1 Schematic of the fabrication process of nanostructured LED chip

Table 1 Parameters of the ICP etching

Materials	Gas flow/sccm		Pressure/Pa	Power/W	Time/s
Al₂O₃	BCl₃	40	1.0664	400	240
Al₂O₃	Ar	10	1.0664	400	240
GaN	BCl₃	20	0.5332	550	25
GaN	Cl₂	30	0.5332	550	25

Fig. 2 SEM images of the AAO membrane which pore widening by increasing etching time and calculated scale distribution of the pore diameter in (a1-a4) (a1) 60 s; (a2) 120 s; (a3) 180 s; (a4) 240 s. (b1-b4) correspond to (a1-a4)

Fig. 3 Curve of the pore diameter with the etching time (a) and curve of the etching rate with the pore diameter (b)

Table 2 Statistics of pore diameter and etching rate with ICP etching for different durations

t/s	D/nm	V/(nm·s^-1)
0	251.37	0.141
30	259.85	0.159
60	270.48	0.199
90	283.70	0.255
120	301.12	0.313
150	321.28	0.368
180	345.29	0.426
210	372.45	0.476
240	402.45	0.500
270	432.53	0.501

Fig. 4 SEM images of nanostructured LED chip (a) Cross sectional view; (b) Oblique view

Fig. 5 PL spectra of nanostructured LEDs with different pore diameter (a) and different depths (b)

References 30

[1]	CHO J, PARK J H, KIM J K , et al. White light-emitting diodes: history, progress, and future. Laser & Photonics Reviews, 2017,11(2):1600147.
[2]	LI Y, WANG W, HUANG L , et al. High-performance vertical GaN-based near-ultraviolet light-emitting diodes on Si substrates. Journal of Materials Chemistry C, 2018,6(42):11255-11260.
[3]	LUO X, HU R, LIU S , et al. Heat and fluid flow in high-power LED packaging and applications. Progress in Energy and Combustion Science, 2016,56:1-32.
[4]	FERREIRA R X G, XIE E, MCKENDRY J J D , et al. High bandwidth GaN-based micro-LEDs for multi-Gb/s visible light communications. IEEE Photonics Technology Letters, 2016,28(19):2023-2026.
[5]	CHO J, SCHUBERT E F, KIM J K . Efficiency droop in light- emitting diodes: challenges and countermeasures. Laser & Photonics Reviews, 2013,7(3):408-421.
[6]	WIERER JR J J, TSAO J Y, SIZOV D S . Comparison between blue lasers and light-emitting diodes for future solid-state lighting. Laser & Photonics Reviews, 2013,7(6):963-993.
[7]	NAKAMURA S, KRAMES M R . History of gallium-nitride-based light-emitting diodes for illumination. Proceedings of the IEEE, 2013,101(10):2211-2220.
[8]	LAI C F, KUO H C, CHAO C H , et al. Structural effects on highly directional far-field emission patterns of GaN-based micro-cavity light-emitting diodes with photonic crystals. Journal of Lightwave Technology, 2010,28(19):2881-2889.
[9]	WANG S C, CHENG Y W, YIN Y F , et al. Interactions of diffraction modes contributed from surface photonic crystals and nanoholes in a GaN-based light-emitting diode. Journal of Lightwave Technology, 2011,29(24):3772-3776.
[10]	WIESMANN C, BERGENEK K, LINDER N , et al. Photonic crystal LEDs-designing light extraction. Laser & Photonics Reviews, 2009,3(3):262-286.
[11]	WEI T, HUO Z, ZHANG Y , et al. Efficiency enhancement of homoepitaxial InGaN/GaN light-emitting diodes on free-standing GaN substrate with double embedded SiO₂ photonic crystals. Optics Express, 2014,22(104):A1093-A1100.
[12]	LIN C F, YANG Z J, ZHENG J H , et al. Enhanced light output in nitride-based light-emitting diodes by roughening the mesa sidewall. IEEE Photonics Technology Letters, 2005,17(10):2038-2040.
[13]	LEE T X, GAO K F, CHIEN W T , et al. Light extraction analysis of GaN-based light-emitting diodes with surface texture and/or patterned substrate. Optics Express, 2007,15(11):6670-6676. DOI URL PMID
[14]	SONG J O, LEEM D S, KWAK J S , et al. Improvement of the luminous intensity of light-emitting diodes by using highly transparent Ag-indium tin oxide p-type ohmic contacts. IEEE Photonics Technology Letters, 2005,17(2):291-293. DOI URL
[15]	PARK H, BYEON K J, YANG K Y , et al. The fabrication of a patterned ZnO nanorod array for high brightness LEDs. Nanotechnology, 2010,21(35):355304. DOI URL PMID
[16]	AN S J, CHAE J H, YI G C , et al. Enhanced light output of GaN-based light-emitting diodes with ZnO nanorod arrays. Applied Physics Letters, 2008,92(12):121108. DOI URL PMID
[17]	SCHEERLINCK S, DUBRUEL P, BIENSTMAN P , et al. Metal grating patterning on fiber facets by UV-based nano imprint and transfer lithography using optical alignment. Journal of Lightwave Technology, 2009,27(10):1415-1420. DOI URL
[18]	SUN T Y, ZHAO W N, WU X H , et al. Porous light-emitting diodes with patterned sapphire substrates realized by high-voltage self-growth and soft UV nanoimprint processes. Journal of Lightwave Technology, 2014,32(2):326-332. DOI URL
[19]	ZANG K Y, CHUA S J, TENG J H , et al. Nanoepitaxy to improve the efficiency of InGaN light-emitting diodes. Applied Physics Letters, 2008,92(24):243126. DOI URL
[20]	RYU S W, PARK J, OH J K , et al. Analysis of improved efficiency of InGaN light-emitting diode with bottom photonic crystal fabricated by anodized aluminum oxide. Advanced Functional Materials, 2009,19(10):1650-1655. DOI URL
[21]	LEE J, KIM D H, KIM J , et al. GaN-based light-emitting diodes directly grown on sapphire substrate with holographically generated two-dimensional photonic crystal patterns. Current Applied Physics, 2009,9(3):633-635. DOI URL
[22]	DAI T, ZHANG B, KANG X N , et al. Light extraction improvement from GaN-based light-emitting diodes with nano-patterned surface using anodic aluminum oxide template. IEEE Photonics Technology Letters, 2008,20(23):1974-1976. DOI URL
[23]	ZHOU W, MIN G, SONG Z , et al. Enhanced efficiency of light emitting diodes with a nano-patterned gallium nitride surface realized by soft UV nanoimprint lithography. Nanotechnology, 2010,21(20):205304. DOI URL PMID
[24]	FU X X, ZHANG B, KANG X N , et al. GaN-based light-emitting diodes with photonic crystals structures fabricated by porous anodic alumina template. Optics Express, 2011,19(105):A1104-A1108. DOI URL PMID
[25]	LI Y, ZHENG M, MA L , et al. Fabrication of highly ordered nanoporous alumina films by stable high-field anodization. Nanotechnology, 2006,17(20):5101. DOI URL
[26]	CUI L, WANG G G, ZHANG H Y , et al. Progress in preparation of patterned sapphire substrate for GaN-based light emitting diodes. Journal of Inorganic Materials, 2012,27(9):897-905. DOI URL
[27]	LI G, WANG W, YANG W , et al. GaN-based light-emitting diodes on various substrates: a critical review. Reports on Progress in Physics, 2016,79(5):056501. DOI URL PMID
[28]	LEE W, KIM J C, GOSELE U . Spontaneous current oscillations during hard anodization of aluminum under potentiostatic conditions. Advanced Functional Materials, 2010,20(1):21-27. DOI URL
[29]	KOKKORIS G, BOUDOUVIS A G, GOGOLIDES E . Integrated framework for the flux calculation of neutral species inside trenches and holes during plasma etching. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 2006,24(6):2008-2020.
[30]	BORODITSKY M, YABLONOVITCH E . Light-emitting Diode Extraction Efficiency. Light-Emitting Diodes: Research, Manufacturing, and Applications, San Jose, 1997: 119-123.