Multi-section core-shell InGaN/GaN quantum- well nanorod light-emitting diode array Charng-Gan Tu, Yu-Feng Yao, Che-Hao Liao, Chia-Ying Su, Chieh Hsieh, Chi-Ming Weng, Chun-Han Lin, Hao-Tsung Chen, Yean-Woei Kiang, and C. C. Yang* Institute of Photonics and Optoelectronics, and Department of Electrical Engineering, National Taiwan University, 1, Roosevelt Road, Section 4, Taipei, 10617 Taiwan *ccycc@ntu.edu.tw Abstract: The growth of a two-section, core-shell, InGaN/GaN quantum- well (QW) nanorod- (NR-) array light-emitting diode device based on a pulsed growth technique with metalorganic chemical vapor deposition is demonstrated. A two-section n-GaN NR is grown through a tapering process for forming two uniform NR sections of different cross-sectional sizes. The cathodoluminescence (CL), photoluminescence (PL), and electrolumines-cence (EL) characterization results of the two-section NR structure are compared with those of a single-section NR sample, which is prepared under the similar condition to that for the first uniform NR section of the two-section sample. All the CL, PL, and EL spectra of the two- section sample (peaked between 520 and 525 nm) are red-shifted from those of the single-section sample (peaked around 490 nm) by >30 nm in wavelength. Also, the emitted spectral widths of the two-section sample become significantly larger than their counterparts of the single-section sample. The PL spectral full-width at half-maximum increases from ~37 to ~61 nm. Such variations are attributed to the higher indium incorporation in the sidewall QWs of the two-section sample due to the stronger strain relaxation in an NR section of a smaller cross-sectional size and the more constituent atom supply from the larger gap volume between neighboring NRs. ©2015 Optical Society of America OCIS codes: (230.3670) Light-emitting diodes; (250.5590) Quantum-well, -wire and -dot devices. References and links 1. S. D. Hersee, X. Sun, and X. Wang, “The controlled growth of GaN nanowires,” Nano Lett. 6(8), 1808–1811 (2006). 2. X. Wang, X. Sun, M. Fairchild, and S. D. Hersee, “Fabrication of GaN nanowire arrays by confined epitaxy,” Appl. Phys. Lett. 89(23), 233115 (2006). 3. Y. S. Chen, W. Y. Shiao, T. Y. Tang, W. M. Chang, C. H. Liao, C. H. Lin, K. C. Shen, C. C. Yang, M. C. Hsu, J. H. Yeh, and T. C. Hsu, “Threading dislocation evolution in patterned GaN nanocolumn growth and coalescence overgrowth,” J. Appl. Phys. 106(2), 023521 (2009). 4. T. Y. Tang, W. Y. Shiao, C. H. Lin, K. C. Shen, J. J. Huang, S. Y. Ting, T. C. Liu, C. C. Yang, C. L. Yao, J. H. Yeh, T. C. Hsu, W. C. Chen, and L. C. Chen, “Coalescence overgrowth of GaN nanocolumns on sapphire with patterned metal organic vapor phase epitaxy,” J. Appl. Phys. 105(2), 023501 (2009). 5. C. H. Liao, W. M. Chang, H. S. Chen, C. Y. Chen, Y. F. Yao, H. T. Chen, C. Y. Su, S. Y. Ting, Y. W. Kiang, and C. C. Yang, “Geometry and composition comparisons between c-plane disc-like and m-plane core-shell InGaN/GaN quantum wells in a nitride nanorod,” Opt. Express 20(14), 15859–15871 (2012). 6. C. H. Liao, W. M. Chang, Y. F. Yao, H. T. Chen, C. Y. Su, C. Y. Chen, C. Hsieh, H. S. Chen, C. G. Tu, Y. W. Kiang, C. C. Yang, and T.-C. Hsu, “Cross-sectional sizes and emission wavelengths of regularly patterned GaN and core-shell InGaN/GaN quantum-well nanorod arrays,” J. Appl. Phys. 113(5), 054315 (2013). 7. W. Bergbauer, M. Strassburg, Ch. Kölper, N. Linder, C. Roder, J. Lähnemann, A. Trampert, S. Fündling, S. F. Li, H. H. Wehmann, and A. Waag, “N-face GaN nanorods: continuous-flux MOVPE growth and morphological properties,” J. Cryst. Growth 315(1), 164–167 (2011). 8. W. Bergbauer, M. Strassburg, Ch. Kölper, N. Linder, C. Roder, J. Lähnemann, A. Trampert, S. Fündling, S. F. Li, H. H. Wehmann, and A. Waag, “Continuous-flux MOVPE growth of position-controlled N-face GaN nanorods and embedded InGaN quantum wells,” Nanotechnology 21(30), 305201 (2010). 9. X. Wang, S. F. Li, M. S. Mohajerani, J. Ledig, H. H. Wehmann, M. Mandl, M. Strassburg, U. Steegmüller, U. #245764 Received 10 Jul 2015; revised 9 Aug 2015; accepted 9 Aug 2015; published 12 Aug 2015 © 2015 OSA 24 Aug 2015 | Vol. 23, No. 17 | DOI:10.1364/OE.23.021919 | OPTICS EXPRESS 21919