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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 19, Iss. 25 — Dec. 5, 2011
  • pp: 25528–25534
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Optical performance of top-down fabricated InGaN/GaN nanorod light emitting diode arrays

Qiming Li, Karl R. Westlake, Mary H. Crawford, Stephen R. Lee, Daniel D. Koleske, Jeffery J. Figiel, Karen C. Cross, Saeed Fathololoumi, Zetian Mi, and George T. Wang  »View Author Affiliations


Optics Express, Vol. 19, Issue 25, pp. 25528-25534 (2011)
http://dx.doi.org/10.1364/OE.19.025528


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Abstract

Vertically aligned InGaN/GaN nanorod light emitting diode (LED) arrays were created from planar LED structures using a new top-down fabrication technique consisting of a plasma etch followed by an anisotropic wet etch. The wet etch results in straight, smooth, well-faceted nanorods with controllable diameters and removes the plasma etch damage. 94% of the nanorod LEDs are dislocation-free and a reduced quantum confined Stark effect is observed due to reduced piezoelectric fields. Despite these advantages, the IQE of the nanorod LEDs measured by photoluminescence is comparable to the planar LED, perhaps due to inefficient thermal transport and enhanced nonradiative surface recombination.

© 2011 OSA

1. Introduction

Improving the performance of Group-III nitride (AlGaInN) based light emitting diodes (LEDs) has been the intense focus of research and development efforts worldwide. While current LEDs are based on planar thin-film architectures, vertically aligned nanorods (also called nanowires or nanocolumns) are currently being explored as an alternative architecture. Several advantages of nanorod-based LEDs have been recently reported. For example, nanorod-based LEDs enhance light extraction due to light scattering, optical mode elimination, and efficient light out-coupling [1

1. C. H. Kuo, L. C. Chang, C. W. Kuo, and G. C. Chi, “Efficiency improvement of GaN-based light-emitting diode prepared on GaN nanorod template,” IEEE Photon. Technol. Lett. 22(4), 257–259 (2010). [CrossRef]

]. Strain-relaxed, bottom-up nanorod growth also enables high crystalline quality with significantly reduced threading dislocation densities [2

2. S. D. Hersee, X. Y. Sun, and X. Wang, “The controlled growth of GaN nanowires,” Nano Lett. 6(8), 1808–1811 (2006). [CrossRef] [PubMed]

]. Higher indium compositions, which are desired for longer green-red wavelength emission, can be achieved with nanowires because of their compliance properties and strain relief mechanisms [3

3. Q. M. Li and G. T. Wang, “Strain influenced indium composition distribution in GaN/InGaN core-shell nanowires,” Appl. Phys. Lett. 97(18), 181107 (2010). [CrossRef]

,4

4. T. Kuykendall, P. Ulrich, S. Aloni, and P. Yang, “Complete composition tunability of InGaN nanowires using a combinatorial approach,” Nat. Mater. 6(12), 951–956 (2007). [CrossRef] [PubMed]

]. Variability in the emission wavelengths across nanowires within an ensemble can lead to phosphor-free “white” LEDs [5

5. H. W. Lin, Y. J. Lu, H. Y. Chen, H. M. Lee, and S. Gwo, “InGaN/GaN nanorod array white light-emitting diode,” Appl. Phys. Lett. 97(7), 073101 (2010). [CrossRef]

,6

6. H. Sekiguchi, K. Kishino, and A. Kikuchi, “Emission color control from blue to red with nanocolumn diameter of InGaN/GaN nanocolumn arrays grown on same substrate,” Appl. Phys. Lett. 96(23), 231104 (2010). [CrossRef]

]. Additionally, suppressed quantum confined Stark effect (QCSE) [7

7. C. Y. Wang, L. Y. Chen, C. P. Chen, Y. W. Cheng, M. Y. Ke, M. Y. Hsieh, H. M. Wu, L. H. Peng, and J. Huang, “GaN nanorod light emitting diode arrays with a nearly constant electroluminescent peak wavelength,” Opt. Express 16(14), 10549–10556 (2008). [CrossRef] [PubMed]

] and reduced droop in InGaN/GaN nanowires [8

8. H. P. T. Nguyen, S. Zhang, K. Cui, X. Han, S. Fathololoumi, M. Couillard, G. A. Botton, and Z. Mi, “p-Type modulation doped InGaN/GaN dot-in-a-wire white-light-emitting diodes monolithically grown on Si(111),” Nano Lett. 11(5), 1919–1924 (2011). [CrossRef] [PubMed]

] have also been reported.

Growth of InGaN/GaN-based nanorod LEDs by bottom-up methods, including hydride vapor phase epitaxy [9

9. H.-M. Kim, Y.-H. Cho, H. Lee, S. I. Kim, S. R. Ryu, D. Y. Kim, T. W. Kang, and K. S. Chung, “High-brightness light emitting diodes using dislocation-free indium gallium nitride/gallium nitride multiquantum-well nanorod arrays,” Nano Lett. 4(6), 1059–1062 (2004). [CrossRef]

] and molecular beam epitaxy [5

5. H. W. Lin, Y. J. Lu, H. Y. Chen, H. M. Lee, and S. Gwo, “InGaN/GaN nanorod array white light-emitting diode,” Appl. Phys. Lett. 97(7), 073101 (2010). [CrossRef]

,8

8. H. P. T. Nguyen, S. Zhang, K. Cui, X. Han, S. Fathololoumi, M. Couillard, G. A. Botton, and Z. Mi, “p-Type modulation doped InGaN/GaN dot-in-a-wire white-light-emitting diodes monolithically grown on Si(111),” Nano Lett. 11(5), 1919–1924 (2011). [CrossRef] [PubMed]

,10

10. K. Kishino, A. Kikuchi, H. Sekiguchi, and S. Ishizawa, “InGaN/GaN nanocolumn LEDs emitting from blue to red,” Proc. SPIE 6473, 64730T (2007). [CrossRef]

], have been demonstrated. However, relatively low growth temperatures and low V to III ratio are commonly used to promote anisotropic one dimensional crystal growth. Metal catalyzed-grown nanowires also require narrow growth conditions which involves lower than optimal growth temperatures [11

11. G. T. Wang, A. A. Talin, D. J. Werder, J. R. Creighton, E. Lai, R. J. Anderson, and I. Arslan, “Highly aligned, template-free growth and characterization of vertical GaN nanowires on sapphire by metal-organic chemical vapour deposition,” Nanotechnology 17(23), 5773–5780 (2006). [CrossRef]

]. These growth conditions may introduce higher impurities and point defect densities [12

12. A. A. Talin, G. T. Wang, E. Lai, and R. J. Anderson, “Correlation of growth temperature, photoluminescence, and resistivity in GaN nanowires,” Appl. Phys. Lett. 92(9), 093105 (2008). [CrossRef]

,13

13. P. C. Upadhya, Q. M. Li, G. T. Wang, A. J. Fischer, A. J. Taylor, and R. P. Prasankumar, “The influence of defect states on non-equilibrium carrier dynamics in GaN nanowires,” Semicond. Sci. Technol. 25(2), 024017 (2010). [CrossRef]

] than the conditions used for creating commercial-quality planar LEDs and provide less flexibility for adjusting growth parameters to optimize doping concentrations and other desired material properties.

In contrast, nanorods fabricated by top-down methods are etched from planar thin film LED structures grown under optimized growth conditions, obviating these disadvantages. Tapered, non-faceted InGaN-based nanorod LEDs have been previously demonstrated by plasma etching planar LED structures [7

7. C. Y. Wang, L. Y. Chen, C. P. Chen, Y. W. Cheng, M. Y. Ke, M. Y. Hsieh, H. M. Wu, L. H. Peng, and J. Huang, “GaN nanorod light emitting diode arrays with a nearly constant electroluminescent peak wavelength,” Opt. Express 16(14), 10549–10556 (2008). [CrossRef] [PubMed]

,14

14. C. H. Chiu, T. C. Lu, H. W. Huang, C. F. Lai, C. C. Kao, J. T. Chu, C. C. Yu, H. C. Kuo, S. C. Wang, C. F. Lin, and T. H. Hsueh, “Fabrication of InGaN/GaN nanorod light-emitting diodes with self-assembled Ni metal islands,” Nanotechnology 18(44), 445201 (2007). [CrossRef]

]. However, the top-down plasma etching leads to damaged, rough, and non-faceted sidewalls with defects, and leakage currents that limits performance [7

7. C. Y. Wang, L. Y. Chen, C. P. Chen, Y. W. Cheng, M. Y. Ke, M. Y. Hsieh, H. M. Wu, L. H. Peng, and J. Huang, “GaN nanorod light emitting diode arrays with a nearly constant electroluminescent peak wavelength,” Opt. Express 16(14), 10549–10556 (2008). [CrossRef] [PubMed]

]. Here we demonstrate a top-down strategy for creating nanorod LEDs from planar LED wafers using a two-step process that adds a selective anisotropic wet etch after the initial plasma etch to remove the dry etch damage while enabling nanorods with straight and smooth faceted sidewalls and controllable diameters independent of pitch. The nanorod LEDs created by this two-step process show potential for enhancing the internal quantum efficiency (IQE) of InGaN/GaN multi-quantum wells (MQWs).

2. Experimental procedures

For the nanorod LED fabrication, a prototypical InGaN/GaN MQW planar LED structures were first grown on c-plane sapphire in a Veeco D-125 metal organic chemical vapor deposition reactor. The MQW structure consists of a 2.5 µm thick Si-doped n-type GaN layer grown at 1050°C followed by a 5-period MQW comprised of 2.5 nm thick In0.13Ga0.87N wells and 7.2 nm thick GaN barriers grown at 770 °C. In addition, a 22 nm thick p-Al0.2Ga0.8N layer and a 200 nm thick p-type GaN contact layer were grown sequentially after the MQWs. After the growth, a close-packed monolayer of 1 µm diameter silica spheres was then self-assembled on the GaN surface in a Langmuir-Blodgett trough as previously reported [15

15. Q. Li, J. J. Figiel, and G. T. Wang, “Dislocation density reduction in GaN by dislocation filtering through a self-assembled monolayer of silica microspheres,” Appl. Phys. Lett. 94(23), 231105 (2009). [CrossRef]

]. The silica colloid monolayer functions as a mask in subsequent inductively coupled plasma etches. Previously plasma etching has been used to create GaN nanorods [16

16. Y. D. Wang, S. J. Chua, S. Tripathy, M. S. Sander, P. Chen, and C. G. Fonstad, “High optical quality GaN nanopillar arrays,” Appl. Phys. Lett. 86(7), 071917 (2005). [CrossRef]

] and GaN-based LED nanorods [7

7. C. Y. Wang, L. Y. Chen, C. P. Chen, Y. W. Cheng, M. Y. Ke, M. Y. Hsieh, H. M. Wu, L. H. Peng, and J. Huang, “GaN nanorod light emitting diode arrays with a nearly constant electroluminescent peak wavelength,” Opt. Express 16(14), 10549–10556 (2008). [CrossRef] [PubMed]

,14

14. C. H. Chiu, T. C. Lu, H. W. Huang, C. F. Lai, C. C. Kao, J. T. Chu, C. C. Yu, H. C. Kuo, S. C. Wang, C. F. Lin, and T. H. Hsueh, “Fabrication of InGaN/GaN nanorod light-emitting diodes with self-assembled Ni metal islands,” Nanotechnology 18(44), 445201 (2007). [CrossRef]

] using various etch masks. In this work we follow the plasma etch step with a selective KOH-based wet etch (AZ400K photoresist developer, AZ Electronic Materials USA Corp) [17

17. M. A. Miller, M. H. Crawford, A. A. Allerman, K. C. Cross, M. A. Banas, R. J. Shul, J. Stevens, and K. H. A. Bogart, “Smooth and vertical facet formation for AlGaN-based deep-UV laser diodes,” J. Electron. Mater. 38(4), 533–537 (2009). [CrossRef]

,18

18. D. A. Stocker, E. F. Schubert, and J. M. Redwing, “Crystallographic wet chemical etching of GaN,” Appl. Phys. Lett. 73(18), 2654–2656 (1998). [CrossRef]

]. With this etchant, the top Ga-polar c-plane surface has a near-zero etch rate while the {10-10} m-plane sidewalls have a relatively fast etch rate compared to the other planes. As a result, the height of nanorod LEDs remains constant and the tapered sidewalls are eventually replaced with six straight and smooth m-plane sidewalls. The nanorod LED array and the original planar LED control sample were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), transmission electron microscopy (TEM), and temperature (4K-298K) and pump power dependent photoluminescence (PL).

3. Results and discussion

Figure 1(a)
Fig. 1 SEM images of (a) a planar LED wafer covered with a monolayer of self-assembled silica spheres, (b) tapered nanorod LEDs created by plasma etch, and (c) “flashlight” shaped nanorod LEDs array following wet etch. (d) A STEM image of nanorod “flashlight” LEDs showing the position of the InGaN MQWs (bright stripes).
shows a SEM image of a planar LED structure covered with a hexagonal close-packed monolayer of silica spheres. After plasma etching, truncated cone-shaped nanorods are formed (Fig. 1(b)). After, the anisotropic wet etch using AZ400K, nanorods with straight and smooth sidewalls are produced, as seen in Fig. 1(c). The n-type GaN etches more quickly than the p-type GaN, leading to “flashlight” or “golf-tee” shaped nanorod LEDs, as shown in Figs. 1(c) and 1(d). The mechanism responsible for the faster n-type etch rate is not currently known. Previously, p-type GaN has been reported to be resistant to photoelectrochemical etching, as photogenerated holes needed for oxidation of the surface are swept away from the depletion region near the surface into the bulk [19

19. D. Zhuang and J. H. Edgar, “Wet etching of GaN, AIN, and SiC: a review,” Mater. Sci. Eng. Rep. 48(1), 1–46 (2005). [CrossRef]

]. While our etch process is neither photo- nor electrically assisted, it is possible that the presence of holes at the surface or the different surface potential between n-type and p-type GaN [20

20. S. Barbet, R. Aubry, M. A. di Forte-Poisson, J. C. Jacquet, D. Deresmes, T. Melin, and D. Theron, “Surface potential of n- and p-type GaN measured by Kelvin force microscopy,” Appl. Phys. Lett. 93(21), 212107 (2008). [CrossRef]

] is responsible for the difference in wet etch rates observed here.

Bright-field TEM imaging was performed to study the dislocation morphology of the nanorods under multi-beam conditions to reveal dislocations with different Burger’s vectors. Typical TEM images are shown in Fig. 3
Fig. 3 TEM images of etched nanorod LED structures. A dislocation is indicated by the arrow in (a).
. TEM imaging of 100 randomly sampled nanorods reveals that 94 nanorods are free of threading dislocations. The threading dislocation density in the initial planar LEDs epilayers before etching was measured to be ~5 dislocations/µm2 (5 × 108 cm−2), which is typical for commercial quality LEDs. Thus, for nanorod diameters ~150 nm (with cross-sectional area ~0.02 µm−2), the average number of dislocations per nanorod is ~0.1. In reality, each nanorod either has one or more dislocations or is dislocation free. Therefore, unlike bulk LEDs, which have a distribution of dislocations throughout, a nanorod LED array is comprised of individual LED elements which are largely dislocation-free. This nearly dislocation-free nanorod architecture could, compared to planar LEDs, have lower leakage currents, less non-radiative recombination, higher IQE, and higher lifespans. This result also shows that nanorods formed by top-down etching can be nearly dislocation free even though they are not grown strain-relaxed like bottom-up nanowires.

Despite the reduced piezoelectric polarization and their mostly dislocation-free nature, the measured InGaN MQW IQEs of the nanorod and planar LEDs are not significantly different. It is possible that the benefit of fewer dislocations and reduced piezoelectric polarization field is counterbalanced by heating effects or the higher surface to volume ratio, which could promote nonradiative carrier recombination [26

26. E. Garnett and P. Yang, “Light trapping in silicon nanowire solar cells,” Nano Lett. 10(3), 1082–1087 (2010). [CrossRef] [PubMed]

] and space-charge-limited carrier transport [27

27. A. A. Talin, F. Léonard, B. S. Swartzentruber, X. Wang, and S. D. Hersee, “Unusually strong space-charge-limited current in thin wires,” Phys. Rev. Lett. 101(7), 076802 (2008). [CrossRef] [PubMed]

]. Future surface passivation experiments, for example with an AlGaN shell [28

28. A. Armstrong, Q. Li, Y. Lin, A. A. Talin, and G. T. Wang, “GaN nanowire surface state observed using deep level optical spectroscopy,” Appl. Phys. Lett. 96(16), 163106 (2010). [CrossRef]

,29

29. L. Baird, C. P. Ong, R. A. Cole, N. M. Haegel, A. A. Talin, Q. M. Li, and G. T. Wang, “Transport imaging for contact-free measurements of minority carrier diffusion in GaN, GaN/AlGaN, and GaN/InGaN core-shell nanowires,” Appl. Phys. Lett. 98(13), 132104 (2011). [CrossRef]

], may shed further light into the role of surface states in these wet-etched structures.

4. Conclusion

Acknowledgments

D. Koleske and S. Lee acknowledge support from Sandia’s Laboratory Directed Research and Development program. S. Fathololoumi and Z. Mi were funded by the Natural Sciences and Engineering Research Council of Canada. All other authors were supported by Sandia’s Solid-State-Lighting Science Energy Frontier Research Center, funded by the U.S. DOE Office of Basic Energy Sciences. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.

References and links

1.

C. H. Kuo, L. C. Chang, C. W. Kuo, and G. C. Chi, “Efficiency improvement of GaN-based light-emitting diode prepared on GaN nanorod template,” IEEE Photon. Technol. Lett. 22(4), 257–259 (2010). [CrossRef]

2.

S. D. Hersee, X. Y. Sun, and X. Wang, “The controlled growth of GaN nanowires,” Nano Lett. 6(8), 1808–1811 (2006). [CrossRef] [PubMed]

3.

Q. M. Li and G. T. Wang, “Strain influenced indium composition distribution in GaN/InGaN core-shell nanowires,” Appl. Phys. Lett. 97(18), 181107 (2010). [CrossRef]

4.

T. Kuykendall, P. Ulrich, S. Aloni, and P. Yang, “Complete composition tunability of InGaN nanowires using a combinatorial approach,” Nat. Mater. 6(12), 951–956 (2007). [CrossRef] [PubMed]

5.

H. W. Lin, Y. J. Lu, H. Y. Chen, H. M. Lee, and S. Gwo, “InGaN/GaN nanorod array white light-emitting diode,” Appl. Phys. Lett. 97(7), 073101 (2010). [CrossRef]

6.

H. Sekiguchi, K. Kishino, and A. Kikuchi, “Emission color control from blue to red with nanocolumn diameter of InGaN/GaN nanocolumn arrays grown on same substrate,” Appl. Phys. Lett. 96(23), 231104 (2010). [CrossRef]

7.

C. Y. Wang, L. Y. Chen, C. P. Chen, Y. W. Cheng, M. Y. Ke, M. Y. Hsieh, H. M. Wu, L. H. Peng, and J. Huang, “GaN nanorod light emitting diode arrays with a nearly constant electroluminescent peak wavelength,” Opt. Express 16(14), 10549–10556 (2008). [CrossRef] [PubMed]

8.

H. P. T. Nguyen, S. Zhang, K. Cui, X. Han, S. Fathololoumi, M. Couillard, G. A. Botton, and Z. Mi, “p-Type modulation doped InGaN/GaN dot-in-a-wire white-light-emitting diodes monolithically grown on Si(111),” Nano Lett. 11(5), 1919–1924 (2011). [CrossRef] [PubMed]

9.

H.-M. Kim, Y.-H. Cho, H. Lee, S. I. Kim, S. R. Ryu, D. Y. Kim, T. W. Kang, and K. S. Chung, “High-brightness light emitting diodes using dislocation-free indium gallium nitride/gallium nitride multiquantum-well nanorod arrays,” Nano Lett. 4(6), 1059–1062 (2004). [CrossRef]

10.

K. Kishino, A. Kikuchi, H. Sekiguchi, and S. Ishizawa, “InGaN/GaN nanocolumn LEDs emitting from blue to red,” Proc. SPIE 6473, 64730T (2007). [CrossRef]

11.

G. T. Wang, A. A. Talin, D. J. Werder, J. R. Creighton, E. Lai, R. J. Anderson, and I. Arslan, “Highly aligned, template-free growth and characterization of vertical GaN nanowires on sapphire by metal-organic chemical vapour deposition,” Nanotechnology 17(23), 5773–5780 (2006). [CrossRef]

12.

A. A. Talin, G. T. Wang, E. Lai, and R. J. Anderson, “Correlation of growth temperature, photoluminescence, and resistivity in GaN nanowires,” Appl. Phys. Lett. 92(9), 093105 (2008). [CrossRef]

13.

P. C. Upadhya, Q. M. Li, G. T. Wang, A. J. Fischer, A. J. Taylor, and R. P. Prasankumar, “The influence of defect states on non-equilibrium carrier dynamics in GaN nanowires,” Semicond. Sci. Technol. 25(2), 024017 (2010). [CrossRef]

14.

C. H. Chiu, T. C. Lu, H. W. Huang, C. F. Lai, C. C. Kao, J. T. Chu, C. C. Yu, H. C. Kuo, S. C. Wang, C. F. Lin, and T. H. Hsueh, “Fabrication of InGaN/GaN nanorod light-emitting diodes with self-assembled Ni metal islands,” Nanotechnology 18(44), 445201 (2007). [CrossRef]

15.

Q. Li, J. J. Figiel, and G. T. Wang, “Dislocation density reduction in GaN by dislocation filtering through a self-assembled monolayer of silica microspheres,” Appl. Phys. Lett. 94(23), 231105 (2009). [CrossRef]

16.

Y. D. Wang, S. J. Chua, S. Tripathy, M. S. Sander, P. Chen, and C. G. Fonstad, “High optical quality GaN nanopillar arrays,” Appl. Phys. Lett. 86(7), 071917 (2005). [CrossRef]

17.

M. A. Miller, M. H. Crawford, A. A. Allerman, K. C. Cross, M. A. Banas, R. J. Shul, J. Stevens, and K. H. A. Bogart, “Smooth and vertical facet formation for AlGaN-based deep-UV laser diodes,” J. Electron. Mater. 38(4), 533–537 (2009). [CrossRef]

18.

D. A. Stocker, E. F. Schubert, and J. M. Redwing, “Crystallographic wet chemical etching of GaN,” Appl. Phys. Lett. 73(18), 2654–2656 (1998). [CrossRef]

19.

D. Zhuang and J. H. Edgar, “Wet etching of GaN, AIN, and SiC: a review,” Mater. Sci. Eng. Rep. 48(1), 1–46 (2005). [CrossRef]

20.

S. Barbet, R. Aubry, M. A. di Forte-Poisson, J. C. Jacquet, D. Deresmes, T. Melin, and D. Theron, “Surface potential of n- and p-type GaN measured by Kelvin force microscopy,” Appl. Phys. Lett. 93(21), 212107 (2008). [CrossRef]

21.

H. W. Choi, S. J. Chua, A. Raman, J. S. Pan, and A. T. S. Wee, “Plasma-induced damage to n-type GaN,” Appl. Phys. Lett. 77(12), 1795–1797 (2000). [CrossRef]

22.

Y. K. Byeun, K. S. Han, and S. C. Choi, “Influence on the growth temperature for one-dimesional GaN nanostructures by halide vapor-phase epitaxy,” J. Ceram. Process. Res. 6(3), 197–200 (2005).

23.

S. J. Chua, H. W. Choi, J. Zhang, and P. Li, “Vacancy effects on plasma-induced damage to n-type GaN,” Phys. Rev. B 64(20), 205302 (2001). [CrossRef]

24.

H. W. Li, A. H. Chin, and M. K. Sunkara, “Direction-dependent homoepitaxial growth of GaN nanowires,” Adv. Mater. (Deerfield Beach Fla.) 18(2), 216–220 (2006). [CrossRef]

25.

J. Wu, W. Walukiewicz, K. M. Yu, J. W. Ager, E. E. Haller, H. Lu, and W. J. Schaff, “Small band gap bowing in In1-xGaxN alloys,” Appl. Phys. Lett. 80(25), 4741–4743 (2002). [CrossRef]

26.

E. Garnett and P. Yang, “Light trapping in silicon nanowire solar cells,” Nano Lett. 10(3), 1082–1087 (2010). [CrossRef] [PubMed]

27.

A. A. Talin, F. Léonard, B. S. Swartzentruber, X. Wang, and S. D. Hersee, “Unusually strong space-charge-limited current in thin wires,” Phys. Rev. Lett. 101(7), 076802 (2008). [CrossRef] [PubMed]

28.

A. Armstrong, Q. Li, Y. Lin, A. A. Talin, and G. T. Wang, “GaN nanowire surface state observed using deep level optical spectroscopy,” Appl. Phys. Lett. 96(16), 163106 (2010). [CrossRef]

29.

L. Baird, C. P. Ong, R. A. Cole, N. M. Haegel, A. A. Talin, Q. M. Li, and G. T. Wang, “Transport imaging for contact-free measurements of minority carrier diffusion in GaN, GaN/AlGaN, and GaN/InGaN core-shell nanowires,” Appl. Phys. Lett. 98(13), 132104 (2011). [CrossRef]

OCIS Codes
(160.6000) Materials : Semiconductor materials
(230.3670) Optical devices : Light-emitting diodes
(250.5230) Optoelectronics : Photoluminescence
(160.4236) Materials : Nanomaterials
(220.4241) Optical design and fabrication : Nanostructure fabrication

ToC Category:
Optical Devices

History
Original Manuscript: October 6, 2011
Revised Manuscript: November 16, 2011
Manuscript Accepted: November 17, 2011
Published: November 30, 2011

Citation
Qiming Li, Karl R. Westlake, Mary H. Crawford, Stephen R. Lee, Daniel D. Koleske, Jeffery J. Figiel, Karen C. Cross, Saeed Fathololoumi, Zetian Mi, and George T. Wang, "Optical performance of top-down fabricated InGaN/GaN nanorod light emitting diode arrays," Opt. Express 19, 25528-25534 (2011)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-19-25-25528


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References

  1. C. H. Kuo, L. C. Chang, C. W. Kuo, and G. C. Chi, “Efficiency improvement of GaN-based light-emitting diode prepared on GaN nanorod template,” IEEE Photon. Technol. Lett.22(4), 257–259 (2010). [CrossRef]
  2. S. D. Hersee, X. Y. Sun, and X. Wang, “The controlled growth of GaN nanowires,” Nano Lett.6(8), 1808–1811 (2006). [CrossRef] [PubMed]
  3. Q. M. Li and G. T. Wang, “Strain influenced indium composition distribution in GaN/InGaN core-shell nanowires,” Appl. Phys. Lett.97(18), 181107 (2010). [CrossRef]
  4. T. Kuykendall, P. Ulrich, S. Aloni, and P. Yang, “Complete composition tunability of InGaN nanowires using a combinatorial approach,” Nat. Mater.6(12), 951–956 (2007). [CrossRef] [PubMed]
  5. H. W. Lin, Y. J. Lu, H. Y. Chen, H. M. Lee, and S. Gwo, “InGaN/GaN nanorod array white light-emitting diode,” Appl. Phys. Lett.97(7), 073101 (2010). [CrossRef]
  6. H. Sekiguchi, K. Kishino, and A. Kikuchi, “Emission color control from blue to red with nanocolumn diameter of InGaN/GaN nanocolumn arrays grown on same substrate,” Appl. Phys. Lett.96(23), 231104 (2010). [CrossRef]
  7. C. Y. Wang, L. Y. Chen, C. P. Chen, Y. W. Cheng, M. Y. Ke, M. Y. Hsieh, H. M. Wu, L. H. Peng, and J. Huang, “GaN nanorod light emitting diode arrays with a nearly constant electroluminescent peak wavelength,” Opt. Express16(14), 10549–10556 (2008). [CrossRef] [PubMed]
  8. H. P. T. Nguyen, S. Zhang, K. Cui, X. Han, S. Fathololoumi, M. Couillard, G. A. Botton, and Z. Mi, “p-Type modulation doped InGaN/GaN dot-in-a-wire white-light-emitting diodes monolithically grown on Si(111),” Nano Lett.11(5), 1919–1924 (2011). [CrossRef] [PubMed]
  9. H.-M. Kim, Y.-H. Cho, H. Lee, S. I. Kim, S. R. Ryu, D. Y. Kim, T. W. Kang, and K. S. Chung, “High-brightness light emitting diodes using dislocation-free indium gallium nitride/gallium nitride multiquantum-well nanorod arrays,” Nano Lett.4(6), 1059–1062 (2004). [CrossRef]
  10. K. Kishino, A. Kikuchi, H. Sekiguchi, and S. Ishizawa, “InGaN/GaN nanocolumn LEDs emitting from blue to red,” Proc. SPIE6473, 64730T (2007). [CrossRef]
  11. G. T. Wang, A. A. Talin, D. J. Werder, J. R. Creighton, E. Lai, R. J. Anderson, and I. Arslan, “Highly aligned, template-free growth and characterization of vertical GaN nanowires on sapphire by metal-organic chemical vapour deposition,” Nanotechnology17(23), 5773–5780 (2006). [CrossRef]
  12. A. A. Talin, G. T. Wang, E. Lai, and R. J. Anderson, “Correlation of growth temperature, photoluminescence, and resistivity in GaN nanowires,” Appl. Phys. Lett.92(9), 093105 (2008). [CrossRef]
  13. P. C. Upadhya, Q. M. Li, G. T. Wang, A. J. Fischer, A. J. Taylor, and R. P. Prasankumar, “The influence of defect states on non-equilibrium carrier dynamics in GaN nanowires,” Semicond. Sci. Technol.25(2), 024017 (2010). [CrossRef]
  14. C. H. Chiu, T. C. Lu, H. W. Huang, C. F. Lai, C. C. Kao, J. T. Chu, C. C. Yu, H. C. Kuo, S. C. Wang, C. F. Lin, and T. H. Hsueh, “Fabrication of InGaN/GaN nanorod light-emitting diodes with self-assembled Ni metal islands,” Nanotechnology18(44), 445201 (2007). [CrossRef]
  15. Q. Li, J. J. Figiel, and G. T. Wang, “Dislocation density reduction in GaN by dislocation filtering through a self-assembled monolayer of silica microspheres,” Appl. Phys. Lett.94(23), 231105 (2009). [CrossRef]
  16. Y. D. Wang, S. J. Chua, S. Tripathy, M. S. Sander, P. Chen, and C. G. Fonstad, “High optical quality GaN nanopillar arrays,” Appl. Phys. Lett.86(7), 071917 (2005). [CrossRef]
  17. M. A. Miller, M. H. Crawford, A. A. Allerman, K. C. Cross, M. A. Banas, R. J. Shul, J. Stevens, and K. H. A. Bogart, “Smooth and vertical facet formation for AlGaN-based deep-UV laser diodes,” J. Electron. Mater.38(4), 533–537 (2009). [CrossRef]
  18. D. A. Stocker, E. F. Schubert, and J. M. Redwing, “Crystallographic wet chemical etching of GaN,” Appl. Phys. Lett.73(18), 2654–2656 (1998). [CrossRef]
  19. D. Zhuang and J. H. Edgar, “Wet etching of GaN, AIN, and SiC: a review,” Mater. Sci. Eng. Rep.48(1), 1–46 (2005). [CrossRef]
  20. S. Barbet, R. Aubry, M. A. di Forte-Poisson, J. C. Jacquet, D. Deresmes, T. Melin, and D. Theron, “Surface potential of n- and p-type GaN measured by Kelvin force microscopy,” Appl. Phys. Lett.93(21), 212107 (2008). [CrossRef]
  21. H. W. Choi, S. J. Chua, A. Raman, J. S. Pan, and A. T. S. Wee, “Plasma-induced damage to n-type GaN,” Appl. Phys. Lett.77(12), 1795–1797 (2000). [CrossRef]
  22. Y. K. Byeun, K. S. Han, and S. C. Choi, “Influence on the growth temperature for one-dimesional GaN nanostructures by halide vapor-phase epitaxy,” J. Ceram. Process. Res.6(3), 197–200 (2005).
  23. S. J. Chua, H. W. Choi, J. Zhang, and P. Li, “Vacancy effects on plasma-induced damage to n-type GaN,” Phys. Rev. B64(20), 205302 (2001). [CrossRef]
  24. H. W. Li, A. H. Chin, and M. K. Sunkara, “Direction-dependent homoepitaxial growth of GaN nanowires,” Adv. Mater. (Deerfield Beach Fla.)18(2), 216–220 (2006). [CrossRef]
  25. J. Wu, W. Walukiewicz, K. M. Yu, J. W. Ager, E. E. Haller, H. Lu, and W. J. Schaff, “Small band gap bowing in In1-xGaxN alloys,” Appl. Phys. Lett.80(25), 4741–4743 (2002). [CrossRef]
  26. E. Garnett and P. Yang, “Light trapping in silicon nanowire solar cells,” Nano Lett.10(3), 1082–1087 (2010). [CrossRef] [PubMed]
  27. A. A. Talin, F. Léonard, B. S. Swartzentruber, X. Wang, and S. D. Hersee, “Unusually strong space-charge-limited current in thin wires,” Phys. Rev. Lett.101(7), 076802 (2008). [CrossRef] [PubMed]
  28. A. Armstrong, Q. Li, Y. Lin, A. A. Talin, and G. T. Wang, “GaN nanowire surface state observed using deep level optical spectroscopy,” Appl. Phys. Lett.96(16), 163106 (2010). [CrossRef]
  29. L. Baird, C. P. Ong, R. A. Cole, N. M. Haegel, A. A. Talin, Q. M. Li, and G. T. Wang, “Transport imaging for contact-free measurements of minority carrier diffusion in GaN, GaN/AlGaN, and GaN/InGaN core-shell nanowires,” Appl. Phys. Lett.98(13), 132104 (2011). [CrossRef]

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