Formation mechanism of SiGe nanorod arrays by combining nanosphere lithography and Au-assisted chemical etching
© Lai et al; licensee Springer. 2012
Received: 30 November 2011
Accepted: 18 February 2012
Published: 18 February 2012
The formation mechanism of SiGe nanorod (NR) arrays fabricated by combining nanosphere lithography and Au-assisted chemical etching has been investigated. By precisely controlling the etching rate and time, the lengths of SiGe NRs can be tuned from 300 nm to 1μm. The morphologies of SiGe NRs were found to change dramatically by varying the etching temperatures. We propose a mechanism involving a locally temperature-sensitive redox reaction to explain this strong temperature dependence of the morphologies of SiGe NRs. At a lower etching temperature, both corrosion reaction and Au-assisted etching process were kinetically impeded, whereas at a higher temperature, Au-assisted anisotropic etching dominated the formation of SiGe NRs. With transmission electron microscopy and scanning electron microscopy analyses, this study provides a beneficial scheme to design and fabricate low-dimensional SiGe-based nanostructures for possible applications.
Over the past few decades, intensive research efforts have been devoted to the fabrication and characterization of Si-based nanostructures due to their intrinsic physical properties, high packing density, and compatibility with current Si technology . Self-assembled Si-based nanostructures are of particular interest because self-assembly provides a possible way to realize nanostructures without process-induced damages, which are frequently observed in the samples defined by electron (e)-beam lithography or reactive ion etching (RIE) [2, 3]. Ge/Si has become a model system for the fabrication and investigation of nanometer-scale heteroepitaxy due to their moderate lattice mismatch (4.2%) [4, 5]. The fabrication of SiGe nanowire arrays is one of the most interesting topics [6, 7]. Recently, the use of Si-based nanowires as high-performance devices or sensors has been extensively reported [8–12]. There are several methods to fabricate nanowire structures, such as e-beam lithography  and vapor-liquid-solid growth [14–16], and metal-assisted chemical etching [17–20]. Previous works have demonstrated that nanosphere lithography (NSL) provides an efficient way to fabricate self-organized, ordered, and close-packed sphere arrays [21, 22]. However, there have been few studies paying attention on the formation mechanism of SiGe NRs. In this work, we fabricated SiGe NR arrays by combing NSL and Au-assisted chemical etching. The influences of chemical etching conditions on the morphologies of as-etched SiGe NRs were investigated to clarify their formation mechanism.
Results and discussion
In this study, the formation mechanism of SiGe NR arrays fabricated by combining NSL and Au-assisted chemical etching has been investigated. By precisely controlling the etching rate and time, the lengths of the SiGe NRs can be tuned. The morphologies of SiGe NRs changed dramatically by varying the etching temperatures. We propose a mechanism involving a locally temperature-sensitive redox reaction to explain this strong temperature dependence of the morphologies of SiGe NRs. At a lower etching temperature, both corrosion reaction and Au-assisted etching process were kinetically hindered, whereas at a higher temperature, Au-assisted anisotropic etching dominated the formation of SiGe NRs. With TEM and SEM analyses, this study provides a beneficial scheme to design and fabricate low-dimensional SiGe-based nanostructures for possible applications.
The research is supported by the National Science Council of Taiwan under contract numbers NSC 100-2221-E-008-016-MY3, NSC 100-2622-E-008-009-CC3, and NSC-98-2112-M-032-003-MY3. The authors also thank the National Nano Device Laboratories and Center for Nano Science and Technology at National Central University for the facility support.
- Pauzauskie PJ, Yang P: Nanowire photonics. Mater Today 2006, 9: 36–45.View ArticleGoogle Scholar
- Medeiros-Ribeiro G, Brathovski AM, Kamins TI, Ohlberg DAA, Williams RS: Shape transition of germanium nanocrystals on a silicon (001) surface from pyramids to domes. Science 1998, 279: 353–355. 10.1126/science.279.5349.353View ArticleGoogle Scholar
- Kammerer C, Cassabois G, Voisin C, Delalande C, Roussignol P, Gerard JM: Photoluminescence up-conversion in single self-assembled InAs / GaAs quantum dots. Phys Rev Lett 2001, 87: 207401.View ArticleGoogle Scholar
- Medeiros-Ribeiro G, Williams RS: Thermodynamics of coherently-strained Ge x Si1-xnanocrystals on Si(001): alloy composition and island formation. Nano Lett 2007, 7: 223–226. 10.1021/nl062530kView ArticleGoogle Scholar
- Robinson JT, Rastelli A, Schmidt O, Dubon OD: Global faceting behavior of strained Ge islands on Si. Nanotechnology 2009, 20: 085708. 10.1088/0957-4484/20/8/085708View ArticleGoogle Scholar
- Wang X, Pey KL, Choi WK, Ho CKF, Fitzgerald E, Antoniadisa D: Arrayed Si/SiGe nanowire and heterostructure formations via Au-assisted wet chemical etching method. Electrochem Solid-State Lett 2009, 12: K37-K40. 10.1149/1.3093036View ArticleGoogle Scholar
- Geyer N, Huang Z, Fuhrmann B, Grimm S, Reiche M, Duc TKN, de Boor J, Leipner HS, Werner P, Gosele U: Sub-20 nm Si/Ge superlattice nanowires by metal-assisted etching. Nano Lett 2009, 9: 3106–3110. 10.1021/nl900751gView ArticleGoogle Scholar
- Law M, Greene L, Johnson JC, Saykally R, Yang P: Nanowire dye-sensitized solar cells. Nat Mater 2005, 4: 455–459. 10.1038/nmat1387View ArticleGoogle Scholar
- Peng K, Wang X, Lee ST: Silicon nanowire array photoelectrochemical solar cells. Appl Phys Lett 2008, 92: 163103. 10.1063/1.2909555View ArticleGoogle Scholar
- Yu JY, Chung SW, Heath JR: Silicon nanowires: preparation, device fabrication, and transport properties. J Phys Chem B 2000, 104: 11864–11870.View ArticleGoogle Scholar
- Greytak AB, Lauhon LJ, Gudiksen MS, Lieber CM: Growth and transport properties of complementary germanium nanowire field-effect transistors. Appl Phys Lett 2004, 84: 4176–4178. 10.1063/1.1755846View ArticleGoogle Scholar
- Whang SJ, Lee SJ, Yang WF, Cho BJ, Kwong DL: Study on the synthesis of high quality single crystalline Si1-xGexnanowire and its transport properties. Appl Phys Lett 2007, 91: 072105. 10.1063/1.2772665View ArticleGoogle Scholar
- Gangloff L, Minoux E, Teo KBK, Vincent P, Semet VT, Binh VT, Yang MH, Bu IYY, Lacerda RG, Pirio G, Schnell JP, Pribat D, Hasko DG, Amaratunga GAJ, Milne WI, Legagneux P: Self-aligned, gated arrays of individual nanotube and nanowire emitters. Nano Lett 2004, 4(9):1575–1579. 10.1021/nl049401tView ArticleGoogle Scholar
- Wu Y, Fan R, Yang P: Block-by-block growth of single-crystalline Si/SiGe superlattice nanowires. Nano Lett 2002, 2: 83–86. 10.1021/nl0156888View ArticleGoogle Scholar
- Dailey JW, Taraci J, Clement T, Smith DJ, Drucker J, Picraux ST: Vapor-liquid-solid growth of germanium nanostructures on silicon. J Appl Phys 2004, 96: 7556. 10.1063/1.1815051View ArticleGoogle Scholar
- Hochbaum AI, Fan R, He R, Yang P: Controlled growth of Si nanowire arrays for device integration. Nano Lett 2005, 5: 457–460. 10.1021/nl047990xView ArticleGoogle Scholar
- Li X, Bohn PW: Metal-assisted chemical etching in HF/H2O2produces porous silicon. Appl Phys Lett 2000, 77: 2572. 10.1063/1.1319191View ArticleGoogle Scholar
- Fuhrmann B, Leipner HS, Hoche HR: Ordered arrays of silicon nanowires produced by nanosphere lithography and molecular beam epitaxy. Nano Lett 2005, 5: 2524–2527. 10.1021/nl051856aView ArticleGoogle Scholar
- Zhang ML, Peng KQ, Fan X, Jie JS, Zhang RQ, Lee ST, Wong NB: Preparation of large-area uniform silicon nanowires arrays through metal-assisted chemical etching. J Phys Chem C 2008, 112: 4444–4450. 10.1021/jp077053oView ArticleGoogle Scholar
- Huang Z, Zhang X, Reiche M, Liu L, Lee W, Shimizu T, Senz S, Gsele U: Extended arrays of vertically aligned sub-10 nm diameter  Si nanowires by metal-assisted chemical etching. Nano Lett 2008, 8: 3046–3051. 10.1021/nl802324yView ArticleGoogle Scholar
- Hulteen JC, Duyne RPV: Nanosphere lithography: a materials general fabrication process for periodic particle array surfaces. J Vac Sci Technol A 1995, 13: 1553–1558. 10.1116/1.579726View ArticleGoogle Scholar
- Wang X, Summers CJ, Wang ZL: Large-scale hexagonal-patterned growth of aligned ZnO nanorods for nano-optoelectronics and nanosensor arrays. Nano Lett 2004, 4: 423–426. 10.1021/nl035102cView ArticleGoogle Scholar
- Peng K, Hu J, Yan Y, Wu Y, Fang H, Xu Y, Lee ST, Zhu J: Fabrication of single-crystalline silicon nanowires by scratching a silicon surface with catalytic metal particles. Adv Funct Mater 2006, 16: 387–394. 10.1002/adfm.200500392View ArticleGoogle Scholar
- Katsaros G, Rastelli A, Stoffel M, Isella G, Känel HV, Bittner AM, Tersoff J, Denker U, Schmidt OG, Costantini G, Kern K: Investigating the lateral motion of SiGe islands by selective chemical etching. Surf Sci 2006, 600: 2608–2613. 10.1016/j.susc.2006.04.027View ArticleGoogle Scholar
- Canham LT: Bioactive silicon structure fabrication through nanoetching techniques. Adv Mater 1995, 7: 1033–1037. 10.1002/adma.19950071215View ArticleGoogle Scholar
- Lin VSY, Motesharei K, Dancil KPS, Sailor MJ, Ghadiri MR: A porous silicon-based optical interferometric biosensor. Science 1997, 278: 840–843. 10.1126/science.278.5339.840View ArticleGoogle Scholar
- Lee SW, Chueh YL, Chen LJ, Chou LJ, Chen PS, Tsai MJ, Liu CW: Formation of SiCH6-mediated Ge quantum dots with strong field emission properties by ultra-high vacuum chemical vapor deposition. J Appl Phys 2005, 98: 073506. 10.1063/1.2060951View ArticleGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.