由於氮化鎵具有極佳之光電特性，常用以製作發光二極體、雷射二極體、太陽能電池、光感測元件、高功率電晶體以及高載子遷移率電晶體。一維奈米結構具有獨特非均向(anisotropic)特性，已廣泛應用於各種光電元件之製作。本研究將結合氮化鎵與一維奈米結構之優勢，以本實驗室自行開發之爐管型電漿輔助化學氣相沉積設備，成長一維氮化鎵奈米結構。本論文可概分為兩大部分，分別為採用鎳觸媒以氣−固−固機制成長氮化鎵奈米線；另一部分為採用無觸媒之成長機制，成長氮化鎵奈米柱。
在第一部分之研究中，我們發現在過量的鎵蒸氣環境下，會導致氮化鎵奈米線之側向成長，並發展出角錐及鋸齒狀等結構。然，在適當的氫氣含量下，可藉由氫電漿與鎵原子之反應，使鎵原子自基板或氮化鎵奈米線表面脫附，令奈米線表面之鎵原子濃度下降，進而達到抑制奈米線表面之成核與成長，以維持一維結構之形貌。此外，本研究採用氮化鎂作為p型氮化鎵之摻雜前驅物，成長具軸向p−n接面之氮化鎵奈米線。為進一步探討氮化鎵奈米線之電性，本研究採用交流電場輔助法，製作氮化鎵奈米線之兩端元件。藉由兩端元件之電流−電壓特性曲線，可確認n型與p型氮化鎵奈米線分別與鋁電極及鎳電極間形成歐姆接觸，且本研究所成長之氮化鎵奈米線，的確具有軸向p−n接面。
在第二部分中，本研究成功在Si(100)及c-Sapphire基板上，長出垂直於基板表面之氮化鎵奈米柱。為探討開始進行成長氮化鎵奈米柱前之基板表面狀態，本研究在系統已升至成長溫度，在尚未啟動電漿前，將基板移至系統低溫水冷區，藉由低溫避免基板上之沉積物的熱裂解，並以AFM分析基板之表面狀態。由AFM分析可知，在開始進行成長前，基板上便已沉積三維島狀結構，推測應為金屬鎵之液滴。為探討所成長之奈米柱極性，本研究藉由KOH進行濕式蝕刻，並發現蝕刻後之氮化鎵奈米柱直徑大幅縮減，然，其底部直徑與蝕刻前並無明顯差異。此實驗結果證實本研究所成長之氮化鎵奈米柱同時具有Ga-polar之核及N-polar的殼，兩者之間應存在反轉區塊界面。本研究亦成長了具p−n接面之氮化鎵奈米柱，並製作為發光二極體。由元件之電流−電壓整流曲線可證實p−n接面之存在。此外，在30 mA之驅動電流下，也觀察到紫色的電致發光現象。本論文也提出影響氮化鎵奈米柱發光二極體之輻射複合效率及內部量子效率之潛在因子，包含Shockley-Read-Hall非輻射複合、電子溢流及通道窄化。本論文也針對以上現象，提出可行之方法，未來將具有朝向大面積且採用任意基板製作奈米柱發光二極體發展之潛力。

GaN is an excellent semiconductor material for the application of light emitting diode, laser diode, sensor and high mobility transistor due to its nature property. The anisotropic property of 1-D nano-structure has been applied in many fields such as optoelectronic devices. In this work, we combine these two advantages and present a homemade PEVCD system for the 1-D nano structural GaN growth. There are two sections in this work; the first one is mainly about the growth of GaN nanowires with nickel as catalyst by VSS growth mechanism. The second part is about growing GaN nanorods via self-assembled mechanism.
In the first part, we have found that the lateral homoepitaxial growth on GaN nanowires is suppressed by introducing hydrogen gas into the plasma-enhanced chemical vapor deposition (PECVD) apparatus for the growth of GaN nanowires. The formation of GaHx (x=2, 3) species due to the reaction between gallium atoms and hydrogen plasma is shown to decrease the amount of excess gallium atoms adsorbed on GaN nanowire surfaces, which results in the elimination of nucleation on the nanowire surface and thus improves the surface smoothness of the nanowire. The stacked-cone nanostructures appear under low hydrogen or hydrogen-less conditions, but completely disappear under high hydrogen conditions in the PECVD system. The mechanism of the elimination of lateral growth on the nanowire surface is further proposed.
Due to the n-type characteristics of intrinsic gallium nitride (GaN), p-type GaN is more difficult to synthesize than n-GaN in forming the p–n junctions for optoelectronic applications. For the growth of the p-type gallium nitride, magnesium is used as the dopant. The Mg-doped GaN nanowires (NWs) have been synthesized on (111)-oriented silicon substrates by plasma-enhanced chemical vapor deposition. The scanning electron microscope images showed that the GaN NWs were bent at high Mg doping levels, and the transmission electron microscope characterization indicated that single-crystalline GaN NWs grew along <0001> orientation. As shown by energy dispersive spectroscopy, the Mg doping levels in GaN NWs increased with increasing partial pressure of magnesium nitride, which was employed as the dopant precursor for p-GaN NW growth. Photoluminescence measurements suggested the presence of both p- and n‐type GaN NWs. Furthermore, the GaN NWswith axial p–n junctionswere aligned between either two-Ni or two-Al electrodes by applying alternating current voltages. The current–voltage characteristics have confirmed the formation of axial p–n junctions in GaN nanowires.
In the second part, vertically-aligned GaN nanorods are successfully grown on the Si(100) and c-sapphire substrate. The growth mechanism are investigated and believed to grow via drop-epitaxy. We found that some islands were formed in the very early stage of growth which is believed to be Ga droplets since the nitrogen-plasma was not even turned on at this moment and these results were supported by performing AFM analysis on the substrate surface. After the wet etching GaN nanorods by means of KOH, we obtained a nanowire with identical diameter. These results indicated that both N-polarity and Ga-polarity are existed within the nanowire structure.
The GaN nanorods with p−n junctions were made into light emitting diode devices. The rectifying I−V curves further confirm the formation of p−n junction in the GaN nanorods. The violet electroluminescence was also observed under 30 mA. We also suggested some factors that played important roles for reducing the radiative recombination efficiency of GaN nanorods-based LED, including Shockley-Read-Hall recombination, electron overflow and channel narrowing. In the end of this thesis, we propose some ways to resolve the problems we’ve met and hopefully make the potentiality of large area and flexible LEDs into reality.

[1] http://visibleearth.nasa.gov/view.php?id=55167
[2] http://www1.eere.energy.gov/buildings/ssl/sslbasics_whyssl.html
[3] http://apps1.eere.energy.gov/buildings/publications/pdfs/ssl/ssl2012_en
ergysavings_factsheet.pdf
[4] H. J. Round, “A Note on Carborundum,” Electrical World, vol. 49, pp. 309, 1907.
[5] E. F. Schubert, Light Emitting Diodes, Cambridge University Press, 2006.
[6] R. Juza and H. Hahn, “On the crystal structure of Cu3N, GaN and InN (translated from German),” Zeitschrift fuer anorganische und allgemeine Chemie, vol. 239, pp. 282, 1938.
[7] M. R. Lorenz and B. B. Binkowski, “Preparation, stability, and luminescence of gallium nitride,” Journal of Electrochemistry Society, vol. 109, pp. 24, 1962.
[8] H. P. Maruska and J. J. Tietjen, “The preparation and properties of vapour-deposited single-crystalline GaN,” Applied Physics Letters, vol. 15, pp. 327, 1969.
[9] J. I. Pankove, E. A. Miller, D. Richman and J. E. Berkeyheiser, “Electroluminescence in GaN,” Journal of Luminescence, vol.4, pp. 63, 1971.
[10] J. I. Pankove, E. A. Miller and J. E. Berkeyheiser, “GaN electroluminescent diodes,” RCA Review, vol. 32, pp. 383, 1971.
[11] H. P. Maruska, W. C. Rhines and D. A. Stevenson, “Preparation of Mg-doped GaN diodes exhibiting violet electroluminescence,” Material Research Bulletin, vol. 7, pp. 777, 1972.
[12] H. Amano, M. Kito, K. Hiramatsu and I. Akasaki, “P-type conduction in Mg-doped GaN treated with low-energy electron beam irradiation (LEEBI),” Japanese Journal of Applied Physics, vol. 28, pp. L2112, 1989.
[13] S. Nakamura, N. Iwasa and M. Senoh, “Method of manufacturing p-type compound semiconductor,” US Patent, 5306662, 1994.
[14] http://www.asu.edu/clas/csss/NUE/index.html
[15] W. Lu, P. Xie and C. M. Lieber, “Nanowire transistor performance limits and applications,” IEEE Transactions on Electron Devices, vol. 55, pp. 2859, 2008.
[16] F. Qian, S. Gradečak, Y. Li, C. Wen, and C. M. Lieber, “Core/multishell nanowire heterostructures as multicolor, high-efficiency light-emitting diodes,” Nano Letters, vol. 5, pp. 2287, 2005.
[17] M. A. Zimmler, F. Capasso, S. Müller and C. Ronning, ”Optically pumped nanowire lasers: invited review," Semiconductor Science and Technology, vol. 25, pp. 024001, 2010.
[18] B. Tian, T. J. Kempa and C. M. Lieber, “Single nanowire photovoltaics,” Chemical Society Reviews, vol. 38, pp. 16, 2009.
[19] E. C. Garnett, M. L. Brongersma, Y. Cui, and M. D. McGehee, “Nanowire solar cells,” Annual Review of Materials Research, vol. 41, pp. 269, 2011.
[20] V. Dobrokhotov, D. N. McIlroy, M. G. Norton, A. Abuzir, W. J. Yeh, I. Stevenson, R. Pouy, J. Bochenek, M. Cartwright, L. Wang, J. Dawson, M. Beaux and C. Berven, “Principles and mechanisms of gas sensing by GaN nanowires functionalized with gold nanoparticles,” Journal of Applied Physics, vol. 99, pp. 104302, 2006.
[21] A. K. Wanekaya, W. Chen, N. V. Myung and A. Mulchandani, “Nanowire-based electrochemical biosensors,” Electroanalysis, vol. 18, pp. 533, 2006.
[22] P. Yang, R. Yan, and M. Fardy, “Semiconductor nanowire: what’s next?” Nano Letters, vol. 10, pp. 1529, 2010.
[23] http://gizmodo.com/360260/nokia-morph-cellphone-rolls-up-stretches-cleans-itself
[24] http://www.youtube.com/watch?v=IX-gTobCJHs
[25] J. Piprek, R. Farrell, S. DenBaars and S. Nakamura, “Effects on built-in polarization on InGaN-GaN vertical cavity surface-emitting Lasers,” IEEE Photonics Technology Letters, vol. 18, pp. 7, 2006.
[26] H. Masui, A. Chakraborty, B. A. Haskell, U. K. Mishra, J. S. Speck, S. Nakamura and S. P. Denbaars, “Polarized light emission from nonpolar InGaN light-emitting diodes grown on a bulk m-plane GaN substrate,” Japanese Journal of Applied Physics, 44(43), L1329, 2005.
[27] W. L. Wilson, P. F. Szajowski, and L. E. Brus, "Quantum confinement in size-selected, surface-oxidized silicon nanocrystals," Science, vol. 262, pp. 1242-1244, 1993.
[28] N. Mingo, "Thermoelectric figure of merit of II-VI semiconductor nanowires," Applied Physics Letters, vol. 85, pp. 5986-5988, 2004.
[29] S. Nakamura, S. Pearton, and G. Fasol, The Blue Laser Diode: The Complete Story, Second ed. Berlin: Springer-Verlag, 2000.
[30] S. Porowski, "Growth and properties of single crystalline GaN substrates and homoepitaxial layers," Materials science & engineering. B, Solid-state materials for advanced technology, vol. B44, pp. 407-413, 1997.
[31] S. F. Li, S. Fuendling, X. Wang, S. Merzsch, M. A. M. Al-Suleiman, J. D. Wei, et al., "Polarity and its influence on growth mechanism during MOVPE growth of GaN sub-micrometer rods," Crystal Growth and Design, vol. 11, pp. 1573-1577, 2011.
[32] M. E. Levinshteĭn, S. L. Rumyantsev, and M. S. Shur, Properties of Advanced Semiconductor Materials: GaN, AlN, InN, BN, and SiGe. New York: John Wiley and Sons, 2001.
[33] D. I. Florescu, V. M. Asnin, F. H. Pollak, A. M. Jones, J. C. Ramer, M. J. Schurman, et al., "Thermal conductivity of fully and partially coalesced lateral epitaxial overgrown GaN/sapphire (0001) by scanning thermal microscopy," Applied Physics Letters, vol. 77, pp. 1464-1466, 2000.
[34] J. H. Edgar, Properties, processing and applications of gallium nitride and related semiconductors. London: INSPEC, 1999.
[35] S. O. Kucheyev, J. E. Bradby, J. S. Williams, C. Jagadish, M. Toth, M. R. Phillips, et al., "Nanoindentation of epitaxial GaN films," Applied Physics Letters, vol. 77, pp. 3373-3375, 2000.
[36] H. Morkoç, Nitride Semiconductors and Devices. Berlin: Springer-Verlag, 1999.
[37] Y. Huang, X. Duan, Y. Cui, and C. M. Lieber, "Gallium Nitride Nanowire Nanodevices," Nano Letters, vol. 2, pp. 101-104, 2002.
[38] J. Neugebauer and C. G. Van de Walle, "Chemical trends for acceptor impurities in GaN," Journal of Applied Physics, vol. 85, pp. 3003-3005, 1999.
[39] J. C. Zolper, R. G. Wilson, S. J. Pearton, and R. A. Stall, "Ca and O ion implantation doping of GaN," Applied Physics Letters, vol. 68, pp. 1945-1945, 1996.
[40] E. Monroy, T. Andreev, P. Holliger, E. Bellet-Amalric, T. Shibata, M. Tanaka, et al., "Modification of GaN(0001) growth kinetics by Mg doping," Applied Physics Letters, vol. 84, pp. 2554-2556, Apr 2004.
[41] A. Salvador, W. Kim, O. Aktas, A. Botchkarev, Z. Fan, and H. Morkoc, "Near ultraviolet luminescence of Be doped GaN grown by reactive molecular beam epitaxy using ammonia," Applied Physics Letters, vol. 69, pp. 2692-2692, 1996.
[42] P. Bergman, G. Ying, B. Monemar, and P. O. Holtz, "Time-resolved spectroscopy of Zn- and Cd-doped GaN," Journal of Applied Physics, vol. 61, pp. 4589-4592, 1987.
[43] S. Strite and H. Morkoç, "GaN, AlN, and InN: A review," Journal of Vacuum Science and Technology B, vol. 10, pp. 1237-1266, 1992.
[44] C. G. Van De Walle, C. Stampfl, and J. Neugebauer, "Theory of doping and defects in III-V nitrides," Journal of Crystal Growth, vol. 189-190, pp. 505-510, 1998.
[45] E. Cimpoiasu, E. Stern, R. Klie, R. A. Munden, G. Cheng, and M. A. Reed, "The effect of Mg doping on GaN nanowires," Nanotechnology, vol. 17, pp. 5735-5739, Dec 2006.
[46] G. S. Cheng, A. Kolmakov, Y. X. Zhang, M. Moskovits, R. Munden, M. A. Reed, et al., "Current rectification in a single GaN nanowire with a well-defined p-n junction," Applied Physics Letters, vol. 83, pp. 1578-1580, Aug 2003.
[47] Z. H. Zhong, F. Qian, D. L. Wang, and C. M. Lieber, "Synthesis of p-type gallium nitride nanowires for electronic and photonic nanodevices," Nano Letters, vol. 3, pp. 343-346, Mar 2003.
[48] J. R. Soulen, P. Sthapitanonda, and J. L. Margrave, "Vaporization of inorganic substances: B2O3, TeO2 and Mg3N2," Journal of Physical Chemistry, vol. 59, pp. 132-136, 1955.
[49] E. T. Yu, X. Z. Dang, P. M. Asbeck, and S. S. Lau, "Spontaneous and piezoelectric polarization effects in III–V nitride heterostructures," Journal of Vacuum Science and Technology B, vol. 17, pp. 1742-1749, 1999.
[50] A. Konar, A. Verma, T. Fang, P. Zhao, R. Jana, and D. Jena, "Charge transport in non-polar and semi-polar III-V nitride heterostructures," Semiconductor Science and Technology, vol. 27, 2012.
[51] S. F. Chichibu, A. Uedono, T. Onuma, B. A. Haskell, A. Chakraborty, T. Koyama, et al., "Origin of defect-insensitive emission probability in In-containing (Al,In,Ga)N alloy semiconductors," Nature Materials, vol. 5, pp. 810-816, 2006.
[52] M. C. Schmidt, K.-C. Kim, R. M. Farrell, D. F. Feezell, D. A. Cohen, M. Saito, et al., "Demonstration of nonpolar m-plane InGaN/GaN laser diodes," Japanese Journal of Applied Physics, Part 2: Letters, vol. 46, pp. L190-L191, 2007.
[53] K. Domen, K. Horino, A. Kuramata, and T. Tanahashi, "Analysis of polarization anisotropy along the c axis in the photoluminescence of wurtzite GaN," Applied Physics Letters, vol. 71, pp. 1996-1996, 1997.
[54] H. Masui, A. Chakraborty, B. A. Haskell, U. K. Mishra, J. S. Speck, S. Nakamura, et al., "Polarized light emission from nonpolar InGaN light-emitting diodes grown on a bulk m-plane GaN substrate," Japanese Journal of Applied Physics, Part 2: Letters, vol. 44, pp. L1329-L1332, 2005.
[55] D. Zubia and S. D. Hersee, "Nanoheteroepitaxy: The application of nanostructuring and substrate compliance to the heteroepitaxy of mismatched semiconductor materials," Journal of Applied Physics, vol. 85, pp. 6492-6496, 1999.
[56] A. Waag, X. Wang, S. Fundling, J. Ledig, M. Erenburg, R. Neumann, et al., "The nanorod approach: GaN NanoLEDs for solid state lighting," Physica Status Solidi (C) Current Topics in Solid State Physics, vol. 8, pp. 2296-2301, 2011.
[57] S. Li and A. Waag, "GaN based nanorods for solid state lighting," Journal of Applied Physics, vol. 111, p. 071101, 2012.
[58] T. Onuma, H. Amaike, M. Kubota, K. Okamoto, H. Ohta, J. Ichihara, et al., "Quantum-confined Stark effects in the m-plane In0.15Ga 0.85N/GaN multiple quantum well blue light-emitting diode fabricated on low defect density freestanding GaN substrate," Applied Physics Letters, vol. 91, p. 181903, 2007.
[59] 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," Applied Physics Letters, vol. 96, p. 231104, 2010.
[60] H. J. Fan, P. Werner, and M. Zacharias, "Semiconductor nanowires: From self-organization to patterned growth," Small, vol. 2, pp. 700-717, 2006.
[61] G. Seryogin, I. Shalish, W. Moberlychan, and V. Narayanamurti, "Catalytic hydride vapour phase epitaxy growth of GaN nanowires," Nanotechnology, vol. 16, pp. 2342-2345, 2005.
[62] J. Li, C. Lu, B. Maynor, S. Huang, and J. Liu, "Controlled Growth of Long GaN Nanowires from Catalyst Patterns Fabricated by "Dip-Pen" Nanolithographic Techniques," Chemistry of Materials, vol. 16, pp. 1633-1636, 2004.
[63] C. Y. Nam, J. Y. Kim, and J. E. Fischer, "Focused-ion-beam platinum nanopatterning for GaN nanowires: Ohmic contacts and patterned growth," Applied Physics Letters, vol. 86, pp. 1-3, 2005.
[64] R. S. Wagner and W. C. Ellis, "Vapor‐Liquid‐Solid Mechanism of Single Crystal Growth," Applied Physics Letters, vol. 4, pp. 89-90, 1964.
[65] B. Liu, Y. Bando, C. Tang, F. Xu, and D. Golberg, "Quasi-aligned single-crystalline GaN nanowire arrays," Applied Physics Letters, vol. 87, p. 073106, 2005.
[66] Y. B. Tang, X. H. Bo, C. S. Lee, H. T. Cong, H. M. Cheng, Z. H. Chen, et al., "Controllable synthesis of vertically aligned p-type GaN nanorod arrays on N-type Si substrates for heterojunction diodes," Advanced Functional Materials, vol. 18, pp. 3515-3522, 2008.
[67] W.-C. Hou, L.-Y. Chen, W.-C. Tang, and F. C. N. Hong, "Control of seed detachment in Au-assisted GaN nanowire growths," Crystal Growth and Design, vol. 11, pp. 990-994, 2011.
[68] W. C. Hou, L. Y. Chen, and F. C. N. Hong, "Fabrication of gallium nitride nanowires by nitrogen plasma," Diamond and Related Materials, vol. 17, pp. 1780-1784, Jul-Oct 2008.
[69] W. C. Hou and F. C.-N. Hong, "Controlled surface diffusion in plasma-enhanced chemical vapor deposition of GaN nanowires," Nanotechnology, vol. 20, 2009.
[70] W.-C. Hou, T.-H. Wu, W.-C. Tang, and F. C.-N. Hong, "Nucleation control for the growth of vertically aligned GaN nanowires," Nanoscale Research Letters, vol. 7, pp. 1-15, 2012.
[71] E. A. Stach, P. J. Pauzauskie, T. Kuykendall, J. Goldberger, R. He, and P. Yang, "Watching GaN nanowires grow," Nano Letters, vol. 3, pp. 867-869, 2003.
[72] J. L. Lensch-Falk, E. R. Hemesath, D. E. Perea, and L. J. Lauhon, "Alternative catalysts for VSS growth of silicon and germanium nanowires," Journal of Materials Chemistry, vol. 19, pp. 849-857, 2009.
[73] S. Kodambaka, J. Tersoff, M. C. Reuter, and F. M. Ross, "Germanium Nanowire Growth Below the Eutectic Temperature," Science, vol. 316, pp. 729-732, 2007.
[74] C. Chèze, L. Geelhaar, O. Brandt, W. M. Weber, H. Riechert, S. Münch, et al., "Direct comparison of catalyst-free and catalyst-induced GaN nanowires," Nano Research, vol. 3, pp. 528-536, 2010.
[75] R. Liu, A. Bell, F. A. Ponce, C. Q. Chen, J. W. Yang, and M. A. Khan, "Luminescence from stacking faults in gallium nitride," Applied Physics Letters, vol. 86, p. 021908, 2005.
[76] P. P. Paskov, R. Schifano, B. Monemar, T. Paskova, S. Figge, and D. Hommel, "Emission properties of a -plane GaN grown by metal-organic chemical-vapor deposition," Journal of Applied Physics, vol. 98, p. 093519, 2005.
[77] J. Yoo, Y.-J. Hong, S. J. An, G.-C. Yi, B. Chon, T. Joo, et al., "Photoluminescent characteristics of Ni-catalyzed GaN nanowires," Applied Physics Letters, vol. 89, p. 043124, 2006.
[78] C. Cheze, L. Geelhaar, B. Jenichen, and H. Riechert, "Different growth rates for catalyst-induced and self-induced GaN nanowires," Applied Physics Letters, vol. 97, p. 153105, 2010.
[79] J. Ristic, E. Calleja, S. Fernandez-Garrido, L. Cerutti, A. Trampert, U. Jahn, et al., "On the mechanisms of spontaneous growth of III-nitride nanocolumns by plasma-assisted molecular beam epitaxy," Journal of Crystal Growth, vol. 310, pp. 4035-4045, 2008.
[80] M. A. Sanchez-Garcia, E. Calleja, E. Monroy, F. J. Sanchez, F. Calle, E. Munoz, et al., "Effect of the III/V ratio and substrate temperature on the morphology and properties of GaN- and AlN-layers grown by molecular beam epitaxy on Si(1 1 1)," Journal of Crystal Growth, vol. 183, pp. 23-30, 1998.
[81] M. Yoshizawa, A. Kikuchi, N. Fujita, K. Kushi, H. Sasamoto, and K. Kishino, "Self-organization of GaN/Al0.18Ga0.82N multi-layer nano-columns on (0 0 0 1) Al2O3 by RF molecular beam epitaxy for fabricating GaN quantum disks," Journal of Crystal Growth, vol. 189-190, pp. 138-141, 1998.
[82] K. A. Bertness, A. Roshko, N. A. Sanford, J. M. Barker, and A. V. Davydov, "Spontaneously grown GaN and AlGaN nanowires," Journal of Crystal Growth, vol. 287, pp. 522-527, 2006.
[83] H. Sekiguchi, T. Nakazato, A. Kikuchi, and K. Kishino, "Structural and optical properties of GaN nanocolumns grown on (0 0 0 1) sapphire substrates by rf-plasma-assisted molecular-beam epitaxy," Journal of Crystal Growth, vol. 300, pp. 259-262, 2007.
[84] O. Landre, C. Bougerol, H. Renevier, and B. Daudin, "Nucleation mechanism of GaN nanowires grown on (111) Si by molecular beam epitaxy," Nanotechnology, vol. 20, 2009.
[85] R. Songmuang, O. Landre, and B. Daudin, "From nucleation to growth of catalyst-free GaN nanowires on thin AlN buffer layer," Applied Physics Letters, vol. 91, p. 251902, 2007.
[86] V. Consonni, M. Knelangen, L. Geelhaar, A. Trampert, and H. Riechert, "Nucleation mechanisms of epitaxial GaN nanowires: Origin of their self-induced formation and initial radius," Physical Review B - Condensed Matter and Materials Physics, vol. 81, 2010.
[87] R. K. Debnath, R. Meijers, T. Richter, T. Stoica, R. Calarco, and H. Luth, "Mechanism of molecular beam epitaxy growth of GaN nanowires on Si(111)," Applied Physics Letters, vol. 90, p. 123117, 2007.
[88] K. A. Bertness, A. Roshko, L. M. Mansfield, T. E. Harvey, and N. A. Sanford, "Nucleation conditions for catalyst-free GaN nanowires," Journal of Crystal Growth, vol. 300, pp. 94-99, 2007.
[89] K. A. Bertness, A. Roshko, L. M. Mansfield, T. E. Harvey, and N. A. Sanford, "Mechanism for spontaneous growth of GaN nanowires with molecular beam epitaxy," Journal of Crystal Growth, vol. 310, pp. 3154-3158, 2008.
[90] H. W. Kim, H. S. Kim, H. G. Na, J. C. Yang, S. S. Kim, and C. Lee, "Self-catalytic growth and characterization of composite (GaN, InN) nanowires," Chemical Engineering Journal, vol. 165, pp. 720-727, 2010.
[91] R. Calarco, R. J. Meijers, R. K. Debnath, T. Stoical, E. Sutter, and H. Luth, "Nucleation and growth of GaN nanowires on Si(111) performed by molecular beam epitaxy," Nano Letters, vol. 7, pp. 2248-2251, 2007.
[92] B. Alloing, S. Vezian, O. Tottereau, P. Vennegues, E. Beraudo, and J. Zuniga-Perez, "On the polarity of GaN micro- and nanowires epitaxially grown on sapphire (0001) and Si(111) substrates by metal organic vapor phase epitaxy and ammonia-molecular beam epitaxy," Applied Physics Letters, vol. 98, p. 011914, 2011.
[93] M. D. Brubaker, I. Levin, A. V. Davydov, D. M. Rourke, N. A. Sanford, V. M. Bright, et al., "Effect of AlN buffer layer properties on the morphology and polarity of GaN nanowires grown by molecular beam epitaxy," 2 Huntington Quadrangle, Suite N101, Melville, NY 11747-4502, United States, 2011.
[94] W. Bergbauer, M. Strassburg, C. H. Kolper, N. Linder, C. Roder, J. Lahnemann, et al., "Continuous-flux MOVPE growth of position-controlled N-face GaN nanorods and embedded InGaN quantum wells," Nanotechnology, vol. 21, 2010.
[95] B. Daudin, J. L. Rouviere, and M. Arlery, "Polarity determination of GaN films by ion channeling and convergent beam electron diffraction," Applied Physics Letters, vol. 69, pp. 2480-2480, 1996.
[96] F. A. Ponce, D. P. Bour, W. T. Young, M. Saunders, and J. W. Steeds, "Determination of lattice polarity for growth of GaN bulk single crystals and epitaxial layers," Applied Physics Letters, vol. 69, pp. 337-337, 1996.
[97] J. D. Wei, S. F. Li, A. Atamuratov, H. H. Wehmann, and A. Waag, "Photoassisted Kelvin probe force microscopy at GaN surfaces: The role of polarity," Applied Physics Letters, vol. 97, p. 172111, 2010.
[98] B. J. Rodriguez, A. Gruverman, A. I. Kingon, and R. J. Nemanich, "Piezoresponse force microscopy for piezoelectric measurements of III-nitride materials," in BNS 2002, May 18, 2002 - May 23, 2002, Amazonas, Brazil, 2002, pp. 252-258.
[99] L. Macht, J. L. Weyher, P. R. Hageman, M. Zielinski, and P. K. Larsen, "The direct influence of polarity on structural and electro-optical properties of heteroepitaxial GaN," Journal of Physics Condensed Matter, vol. 14, pp. 13345-13350, 2002.
[100] N. A. Fichtenbaum, T. E. Mates, S. Keller, S. P. DenBaars, and U. K. Mishra, "Impurity incorporation in heteroepitaxial N-face and Ga-face GaN films grown by metalorganic chemical vapor deposition," Journal of Crystal Growth, vol. 310, pp. 1124-1131, 2008.
[101] H. M. Ng and A. Y. Cho, "Investigation of Si doping and impurity incorporation dependence on the polarity of GaN by molecular beam epitaxy," in 20th North American Conference on Molecular Beam Epitaxy, October 1, 2001 - October 3, 2001, Providence, RI, United states, 2002, pp. 1217-1220.
[102] L. K. Li, M. J. Jurkovic, W. I. Wang, H. J. M. Van, and P. P. Chow, "Surface polarity dependence of Mg doping in GaN grown by molecular-beam epitaxy," Applied Physics Letters, vol. 76, pp. 1740-1742, 2000.
[103] C. T. Foxon, S. V. Novikov, J. L. Hall, R. P. Campion, D. Cherns, I. Griffiths, et al., "A complementary geometric model for the growth of GaN nanocolumns prepared by plasma-assisted molecular beam epitaxy," Journal of Crystal Growth, vol. 311, pp. 3423-3427, 2009.
[104] J. Wei, R. Neumann, X. Wang, S. Li, S. Fundling, S. Merzsch, et al., "Polarity analysis of GaN nanorods by photo-assisted Kelvin probe force microscopy," Physica Status Solidi (C) Current Topics in Solid State Physics, vol. 8, pp. 2157-2159, 2011.
[105] D. Cherns, L. Meshi, I. Griffiths, S. Khongphetsak, S. V. Novikov, N. Farley, et al., "Defect reduction in GaN/(0001)sapphire films grown by molecular beam epitaxy using nanocolumn intermediate layers," Applied Physics Letters, vol. 92, p. 121902, 2008.
[106] M. D. Brubaker, I. Levin, A. V. Davydov, D. M. Rourke, N. A. Sanford, V. M. Bright, et al., "Effect of AlN buffer layer properties on the morphology and polarity of GaN nanowires grown by molecular beam epitaxy," 2 Huntington Quadrangle, Suite N101, Melville, NY 11747-4502, United States, 2011, p. 053506.
[107] W. Q. Han, S. S. Fan, Q. Q. Li, and Y. D. Hu, "Synthesis of gallium nitride nanorods through a carbon nanotube-confined reaction," Science, vol. 277, pp. 1287-1289, Aug 29 1997.
[108] H. W. Li, A. H. Chin, and M. K. Sunkara, "Direction-dependent homoepitaxial growth of GaN nanowires," Advanced Materials, vol. 18, pp. 216-220, Jan 19 2006.
[109] X. M. Cai, A. B. Djurisic, M. H. Xie, C. S. Chiu, and S. Gwo, "Growth mechanism of stacked-cone and smooth-surface GaN nanowires," Applied Physics Letters, vol. 87, p. 183103, Oct 31 2005.
[110] H. Y. Peng, N. Wang, X. T. Zhou, Y. F. Zheng, C. S. Lee, and S. T. Lee, "Control of growth orientation of GaN nanowires," Chemical Physics Letters, vol. 359, pp. 241-245, 2002.
[111] S. Y. Bae, H. W. Seo, D. S. Han, M. S. Park, W. S. Jang, C. W. Na, et al., "Synthesis of gallium nitride nanowires with uniform [0 0 1] growth direction," Journal of Crystal Growth, vol. 258, pp. 296-301, 2003.
[112] X. T. Zhou, T. K. Sham, Y. Y. Shan, X. F. Duan, S. T. Lee, and R. A. Rosenberg, "One-dimensional zigzag gallium nitride nanostructures," Journal of Applied Physics, vol. 97, p. 104315, May 15 2005.
[113] F. Kawamura, M. Imade, M. Yoshimura, Y. Mori, and T. Sasaki, "Synthesis of GaN crystal using gallium hydride," Japanese Journal of Applied Physics Part 2-Letters & Express Letters, vol. 44, pp. L1-L3, 2005 2005.
[114] W. C. Hou and F. C.-N. Hong, "Controlled surface diffusion in plasma-enhanced chemical vapor deposition of GaN nanowires," Nanotechnology, vol. 20, p. 055606, Feb 4 2009.
[115] J. R. Roth, Industrial plasma engineering-Volume 1: Principles Institute of Physics. Bristol and Philadelphia: Institute of Physics Publishing, 1995.
[116] O. Englander, D. Christensen, J. Kim, L. Lin, and S. J. S. Morris, "Electric-field assisted growth and self-assembly of intrinsic silicon nanowires," Nano Letters, vol. 5, pp. 705-708, 2005.
[117] C. S. Lao, J. Liu, P. Gao, L. Zhang, D. Davidovic, R. Tummala, et al., "ZnO nanobelt/nanowire schottky diodes formed by dielectrophoresis alignment across au electrodes," Nano Letters, vol. 6, pp. 263-266, 2006.
[118] S. K. Lee, T. H. Kim, S. Y. Lee, K. C. Choi, and P. Yang, "High-brightness gallium nitride nanowire UV-blue light emitting diodes," Philosophical Magazine, vol. 87, pp. 2105-2115, 2007.
[119] T. H. Kim, S. Y. Lee, N. K. Cho, H. K. Seong, H. J. Choi, S. W. Jung, et al., "Dielectrophoretic alignment of gallium nitride nanowires (GaN NWs) for use in device applications," Nanotechnology, vol. 17, pp. 3394-3399, 2006.
[120] H. A. Pohl and J. S. Crane, "Dielectrophoretic force," Journal of Theoretical Biology, vol. 37, pp. 1-13, 1972.
[121] C. H. Lee, D. R. Kim, and X. Zheng, "Orientation-controlled alignment of axially modulated pn silicon nanowires," Nano Letters, vol. 10, pp. 5116-5122, 2010.
[122] D. L. Fan, R. C. Cammarata, and C. L. Chien, "Precision transport and assembling of nanowires in suspension by electric fields," Applied Physics Letters, vol. 92, p. 093115, 2008.
[123] http://zh.wikipedia.org/wiki/File:Scheme_TEM_en.svg
[124] G. T. Wang, A. A. Talin, D. J. Werder, J. R. Creighton, E. Lai, R. J. Anderson, et al., "Highly aligned, template-free growth and characterization of vertical GaN nanowires on sapphire by metal-organic chemical vapour deposition," Nanotechnology, vol. 17, pp. 5773-5780, 2006.
[125] A. Kuramata, K. Horino, K. Domen, K. Shinohara, and T. Tanahashi, "High-quality GaN epitaxial layer grown by metalorganic vapor phase epitaxy on (111) MgAl2O4 substrate," Applied Physics Letters, vol. 67, pp. 2521-2521, 1995.
[126] W.-C. Hou, L.-Y. Chen, W.-C. Tang, and F. C. N. Hong, "Control of seed detachment in Au-assisted GaN nanowire growths," Crystal Growth and Design, vol. 11, pp. 990-994, 2011.
[127] X. Weng, R. A. Burke, and J. M. Redwing, "The nature of catalyst particles and growth mechanisms of GaN nanowires grown by Ni-assisted metal-organic chemical vapor deposition," Nanotechnology, vol. 20, p. 085610, 2009.
[128] P. Ghekiere, S. Mahieu, G. De Winter, R. De Gryse, and D. Depla, "Scanning electron microscopy study of the growth mechanism of biaxially aligned magnesium oxide layers grown by unbalanced magnetron sputtering," Thin Solid Films, vol. 493, pp. 129-134, 2005.
[129] K. Hiramatsu, K. Nishiyama, A. Motogaito, H. Miyake, Y. Iyechika, and T. Maeda, "Recent progress in selective area growth and epitaxial lateral overgrowth of III-nitrides: Effects of reactor pressure in MOVPE growth," Physica Status Solidi (A) Applied Research, vol. 176, pp. 535-543, 1999.
[130] W. C. Hou and F. C.-N. Hong, "Controlled surface diffusion in plasma-enhanced chemical vapor deposition of GaN nanowires," Nanotechnology, vol. 20, p. 055606, Feb 4 2009.
[131] F. Kawamura, M. Imade, M. Yoshimura, Y. Mori, and T. Sasaki, "Synthesis of GaN crystal using gallium hydride," Japanese Journal of Applied Physics Part 2-Letters & Express Letters, vol. 44, pp. L1-L3, 2005.
[132] A. Koukitu, M. Mayumi, and Y. Kumagai, "Surface polarity dependence of decomposition and growth of GaN studied using in situ gravimetric monitoring," Journal of Crystal Growth, vol. 246, pp. 230-236, 2002.
[133] E. V. Yakovlev, R. A. Talalaev, A. S. Segal, A. V. Lobanova, W. V. Lundin, E. E. Zavarin, et al., "Hydrogen effects in III-nitride MOVPE," Journal of Crystal Growth, vol. 310, pp. 4862-4866, 2008.
[134] S. F. Li, S. Fuendling, X. Wang, S. Merzsch, M. A. M. Al-Suleiman, J. D. Wei, et al., "Polarity and its influence on growth mechanism during MOVPE growth of GaN sub-micrometer rods," Crystal Growth and Design, vol. 11, pp. 1573-1577, 2011.
[135] Z. H. Zhong, F. Qian, D. L. Wang, and C. M. Lieber, "Synthesis of p-type gallium nitride nanowires for electronic and photonic nanodevices," Nano Letters, vol. 3, pp. 343-346, Mar 2003.
[136] W. Kim, A. Salvador, A. E. Botchkarev, O. Aktas, S. N. Mohammad, and H. Morcoc, "Mg-doped p-type GaN grown by reactive molecular beam epitaxy," Applied Physics Letters, vol. 69, pp. 559-559, 1996.
[137] M. Leroux, B. Beaumont, N. Grandjean, P. Lorenzini, S. Haffouz, P. Venne´gue`s, et al., "Luminescence and reflectivity studies of undoped, n- and p-doped GaN on (0001) sapphire," Materials Science and Engineering: B, vol. 50, pp. 97-104, 1997.
[138] J. K. Sheu, Y. K. Su, G. C. Chi, B. J. Pong, C. Y. Chen, C. N. Huang, et al., "Photoluminescence spectroscopy of Mg-doped GaN," Journal of Applied Physics, vol. 84, pp. 4590-4594, 1998.
[139] A. K. Viswanath, E. J. Shin, J. I. Lee, S. Yu, D. Kim, B. Kim, et al., "Magnesium acceptor levels in GaN studied by photoluminescence," Journal of Applied Physics, vol. 83, pp. 2272-2275, 1998.
[140] M. S. Son, S. I. Im, Y. S. Park, C. M. Park, T. W. Kang, and K. H. Yoo, "Ultraviolet photodetector based on single GaN nanorod p-n junctions," Materials Science and Engineering C, vol. 26, pp. 886-888, 2006.
[141] M. Tan, V. Mahalingam, and F. C. J. M. Van Veggel, "White electroluminescence from a hybrid polymer-GaN:Mg nanocrystals device," Applied Physics Letters, vol. 91, pp. 093132-1, 2007.
[142] J. S. Foresi and T. D. Moustakas, "Metal contacts to gallium nitride," Applied Physics Letters, vol. 62, pp. 2859-2859, 1993.
[143] Y. B. Tang, Z. H. Chen, H. S. Song, C. S. Lee, H. T. Cong, H. M. Cheng, et al., "Vertically aligned p-type single-crystalline GaN nanorod arrays on n-type Si for heterojunction photovoltaic cells," Nano Letters, vol. 8, pp. 4191-4195, 2008.
[144] C. H. Lee, D. R. Kim, and X. Zheng, "Orientation-controlled alignment of axially modulated pn silicon nanowires," Nano Letters, vol. 10, pp. 5116-5122, 2010.
[145] H. P. T. Nguyen, M. Djavid, K. Cui, and Z. Mi, "Temperature-dependent nonradiative recombination processes in GaN-based nanowire white-light-emitting diodes on silicon," Nanotechnology, vol. 23, 2012.
[146] R. Calarco, M. Marso, T. Richter, A. I. Aykanat, R. Meijers, A. V. D. Hart, et al., "Size-dependent photoconductivity in MBE-grown GaN - Nanowires," Nano Letters, vol. 5, pp. 981-984, 2005.
[147] A. Waag, X. Wang, S. Fundling, J. Ledig, M. Erenburg, R. Neumann, et al., "The nanorod approach: GaN NanoLEDs for solid state lighting," Physica Status Solidi (C) vol. 8, pp. 2296-2301, 2011.
[148] A. A. Talin, F. Leonard, B. S. Swartzentruber, X. Wang, and S. D. Hersee, "Unusually strong space-charge-limited current in thin wires," Physical Review Letters, vol. 101, p. 076802, 2008.
[149] J. Yoo, Y.-J. Hong, S. J. An, G.-C. Yi, B. Chon, T. Joo, et al., "Photoluminescent characteristics of Ni-catalyzed GaN nanowires," Applied Physics Letters, vol. 89, p. 043124, 2006.
[150] P. Hartman and P. Bennema, "The attachment energy as a habit controlling factor. I. Theoretical considerations," Journal of Crystal Growth, vol. 49, pp. 145-156, 1980.
[151] C. Herring, "Some theorems on the free energies of crystal surfaces," Physical Review, vol. 82, pp. 87-93, 1951.
[152] H. Li, H. Chandrasekaran, M. K. Sunkara, R. Collazo, Z. Sitar, M. Stukowski, et al., "Self-oriented growth of GaN films on molten gallium," in 2004 MRS Fall Meeting, November 29, 2004 - December 3, 2004, Boston, MA, United states, 2005, pp. 703-708.
[153] K. H. Lee, J. Y. Lee, Y. H. Kwon, T. W. Kang, J. H. You, D. U. Lee, et al., "Effects of defects on the morphologies of GaN nanorods grown on Si (111) substrates," Journal of Materials Research, vol. 24, pp. 3032-3037, 2009.
[154] J. E. Northrup, J. Neugebauer, and L. T. Romano, "Inversion domain and stacking mismatch boundaries in GaN," Physical Review Letters, vol. 77, pp. 103-106, 1996.
[155] P. Xiao, X. Wang, J. Wang, F. Ke, M. Zhou, and Y. Bai, "Surface transformation and inversion domain boundaries in gallium nitride nanorods," Applied Physics Letters, vol. 95, p. 211907, 2009.
[156] Y. L. Lai, C. P. Liu, Y. H. Lin, R. M. Lin, D. Y. Lyu, Z. X. Peng, et al., "Effects of the material polarity on the green emission properties of InGaN/GaN multiple quantum wells," Applied Physics Letters, vol. 89, p. 151906, 2006.
[157] J. E. Northrup, "Structure of the {1120} inversion domain boundary in GaN," Physica B: Condensed Matter, vol. 273-274, pp. 130-133, 1999.
[158] J. E. Northrup and J. Neugebauer, "Theory of GaN(1010) and (1120) surfaces," Physical Review B, vol. 53, pp. R10477-R10480, 1996.
[159] J. E. Northrup, L. T. Romano, and J. Neugebauer, "Surface energetics, pit formation, and chemical ordering in InGaN alloys," Applied Physics Letters, vol. 74, pp. 2319-2321, 1999.
[160] S. L. Zhang, A. B. Djuriic, Y. F. Hsu, A. M. C. Ng, and M. H. Xie, "Influence of different insulating polymers on the performance of ZnO nanorod based LEDs," in Proceedings of SPIE, Strasbourg, France, 2008, pp. 69881O-1.
[161] D. A. Neamen, Semiconductor Physics and Devices, Third ed. New York: McGraw-Hill, 2003.