From the nucleation of wiggling Au nanostructures to the dome-shaped Au droplets on GaAs (111)A, (110), (100), and (111)B
© Li et al.; licensee Springer. 2014
Received: 7 February 2014
Accepted: 2 March 2014
Published: 12 March 2014
In this paper, the systematic evolution process of self-assembled Au droplets is successfully demonstrated on GaAs (111)A, (110), (100), and (111)B. On various GaAs substrates, self-assembled Au clusters begin to nucleate at around 300°C, and then, they develop into wiggly Au nanostructures at 350°C. Between 400°C and 550°C, the self-assembled dome-shaped Au droplets with fine uniformity are fabricated with various sizes and densities based on the Volmer-Weber growth mode. Depending on the annealing temperature, the size including the average height and lateral diameter and the density of Au droplets show the opposite trend of increased size with correspondingly decreased density as a function of the annealing temperature due to the difference in the diffusion length of adatoms at varied activation energy. Under an identical growth condition, depending on the surface index, the size and density of Au droplets show a clear distinction, observed throughout the temperature range. The results are systematically analyzed and discussed in terms of atomic force microscopy (AFM) images, cross-sectional line profiles, and Fourier filter transform (FFT) power spectra as well as the summary plots of the size and density.
KeywordsSelf-assembled Au droplets Annealing temperature Various surface indices Nucleation
In this study, the self-assembled Au droplets were fabricated on GaAs (111)A, (111)B, (110), and (100) representing the general zinc blende lattice indices in a pulsed laser deposition (PLD) system. To start with, various index samples were indium-bonded together on an Inconel holder side by side for uniformity per batch and then treated with a degassing process at 350°C for 30 min under 1 × 10−4 Torr. Subsequently, a total amount of 2.5 nm of Au was equally deposited on the samples at a rate of 0.5 Å/s and at an ionization current of 3 mA under 1 × 10−1 Torr in an ion coater chamber. With the aim of investigating the detailed evolution process of the self-assembled Au droplets, each growth was systematically carried out by varying the annealing temperatures (Ta) at 100°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500, and 550°C, respectively. For the systematic growths, the substrate temperature (Ts) was ramped up to the target temperature at a ramp rate of 1.83°C/s under 1 × 10−4 Torr by a computer-operated recipe, and after reaching each target, a dwell time of 450 s was equally given to the samples. After the termination of each growth, the Ts was immediately quenched down to diminish the Ostwald ripening [30, 31]. Following the fabrication, AFM was used for the characterization of surface morphologies, and XEI software was used for the data preparation and analysis of AFM top-view and side-view images and line profiles as well as the Fourier filter transform (FFT) power spectra. The FFT power spectrum represents the height information converted from the real spatial domain to the frequency domain, and thus, the horizontal (x) and vertical (y) information is converted by taking the reciprocal of the corresponding units of x and y from the AFM images; hence, the distribution of color patterns can present the distribution of frequent height with directionality.
Results and discussion
Summary of AH, LD, and AD of self-assembled Au droplets
Average height (AH) [nm]
Average lateral diameter (LD) [nm]
Average density (AD) [×108 cm−2]
The evolution of the self-assembled Au droplets has been successfully demonstrated on GaAs (111)A, (110), (100), and (111)B through the variation of annealing temperature throughout the feasible annealing temperature (Ta) range between 250°C to 550°C. The resulting Au nanostructures were systematically analyzed in terms of AFM images, cross-sectional line profiles, height distribution histograms, and FFT power spectra. The unique nucleation stages of the Au clusters and wiggly nanostructures were observed on various GaAs surfaces at the Ta range between 250°C and 350°C, and the self-assembled dome-shaped Au droplets with excellent uniformity were successfully fabricated between 400°C and 550°C. The average height and lateral diameter of the Au droplets were gradually increased with the increased Ta, and the average density was correspondingly decreased at each Ta point. The nucleation and the formation of Au droplets were described based on the Volmer-Weber growth mode, namely Ea > Ei. The evolution of the size and density of Au droplets was described in terms of the lD of Au adatoms in relation with the thermal dynamic equilibrium along with the Ta. In addition, an apparent distinction in the size and density of Au droplets between various GaAs indices was clearly observed, and it was maintained throughout the Ta range GaAs (111)A > (110) > (100) > (111)B in size and vice versa in diameter, and the trend was described in relation between the Rq and lD. This study can find applications in the nanowire fabrications on various GaAs surfaces.
This work was supported by the National Research Foundation (NRF) of Korea (no. 2011–0030821 and 2013R1A1A1007118). This research was in part supported by the research grant of Kwangwoon University in 2014.
- Steffen B, Carsten P€u, Timur F, Oliver B, Grahn HT, Lutz G, Henning R: Suitability of Au- and self-assisted GaAs nanowires for optoelectronic applications. Nano Lett 2011, 11: 1276–1279. 10.1021/nl104316tView Article
- Wen C-Y, Reuter MC, Bruley J, Tersoff J, Kodambaka S, Stach EA, Ross FM: Formation of compositionally abrupt axial heterojunctions in silicon-germanium nanowires. Science 2009, 326: 1247–1250. 10.1126/science.1178606View Article
- Mahpeykar SM, Koohsorkhi J, Ghafoori-fard H: Ultra-fast microwave-assisted hydrothermal synthesis of long vertically aligned ZnO nanowires for dye-sensitized solar cell application. Nanotechnology 2012, 23: 165602(1)-165602(7).View Article
- Haofeng L, Rui J, Chen C, Zhao X, Wuchang D, Yanlong M, Deqi W, Xinyu L, Tianchun Y: Influence of nanowires length on performance of crystalline silicon solar cell. Appl Phys Lett 2011, 98: 151116(1)-151116(3).
- Tae Hoon S, Bo Kyoung K, GangU S, Changhyup L, Myung Jong K, Hyunsoo K, Eun-Kyung S: Graphene-silver nanowire hybrid structure as a transparent and current spreading electrode in ultraviolet light emitting diodes. Appl Phys Lett 2013, 103: 051105(1)-051105(5).
- Shirak O, Shtempluck O, Kotchtakov V, Bahir G, Yaish YE: High performance horizontal gate-all-around silicon nanowire field-effect transistors. Nanotechnology 2012, 23: 395202(1)-395202(8).View Article
- Jae-Hyuk A, Sung-Jin C, Jin-Woo H, Tae Jung P, Sang Yup L, Yang-Kyu C: Double-gate nanowire field effect transistor for a biosensor. Nano Lett 2010, 10: 2934–2938. 10.1021/nl1010965View Article
- Frajtag P, Hosalli AM, Bradshaw GK, Nepal N, El-Masry NA, Bedair SM: Improved light-emitting diode performance by conformal overgrowth of multiple quantum wells and fully coalesced p-type GaN on GaN nanowires. Appl Phys Lett 2011, 98: 143104(1)-143104(3).
- Ying X, Linyou C, Sonia C-B, Sonia E, Jordi A, Francesca Peiro MH, Zardo I, Morante JR, Brongersma ML, Morral AF: single crystalline and core–shell indium-catalyzed germanium nanowires—a systematic thermal CVD growth study. Nanotechnology 2009, 20: 245608(1)-245608(9).
- Jorg KNL, DjamilaBahloul H, Daniel K, Michael W, Thierry M, Bernd S: TEM characterization of Si nanowires grown by CVD on Si pre-structured by nanosphere lithography. Mater Sci Semicond Process 2008, 11: 169–174. 10.1016/j.mssp.2008.09.016View Article
- Cai Y, Wong TL, Chan SK, Sou IK, Su DS, Wang N: Growth behaviors of ultrathin ZnSe nanowires by Au-catalyzed molecular-beam. epitaxyAppl Phys Lett 2008, 93: 233107(1)-233107(3).
- Tchernycheva M, Harmand JC, Patriarche G, Travers L, Cirlin GE: Temperature conditions for GaAs nanowire formation by Au-assisted molecular beam epitaxy. Nanotechnology 2006, 17: 4025–4030. 10.1088/0957-4484/17/16/005View Article
- Kazuki N, Takeshi Y, Hidekazu T, Tomoji K: Epitaxial growth of MgO nanowires by pulsed laser deposition. Appl Phys Lett 2007, 101: 124304(1)-124304(4).
- Bjorn E, Vladimir S, Andreas B, Silke C: Growth of axial SiGe heterostructures in nanowires using pulsed laser deposition. Nanotechnology 2011, 22: 305604(1)-305604(8).
- Wagner RS, Ellis WC: Vapor liquid solid mechanism of single crystal growth. Appl Phys Lett 1964, 4: 89–90. 10.1063/1.1753975View Article
- Morales AM, Lieber CM: Laser ablation method for the synthesis of crystalline semiconductor nanowires. Science 1998, 279: 208–208. 10.1126/science.279.5348.208View Article
- Volker S, Ulrich G: How nanowires grow. Science 2007, 316: 698–698. 10.1126/science.1142951View Article
- Khac An D, Khang Dao D, Dai Nguyen T, Tuan Phan A, Hung Manh D: The effects of Au surface diffusion to formation of Au droplets/clusters and nanowire growth on GaAs substrate using VLS method. Mater Electron 2012, 23: 2065–2074. 10.1007/s10854-012-0704-yView Article
- Borgstrom M, Deppert K, Samuelson L, Seifert W: Size- and shape-controlled GaAs nano-whiskers grown by MOVPE: a growth study. J Cryst Growth 2004, 260: 18–22. 10.1016/j.jcrysgro.2003.08.009View Article
- Yi C, Lauhon LJ, Gudiksen MS, Jianfang W, Lieber CM: Diameter-controlled synthesis of single-crystal silicon nanowires. Appl Phys Lett 2001, 78: 2214–2216. 10.1063/1.1363692View Article
- Pin Ann L, Dong L, Samantha R, Xuan P, Gao A, Mohan Sankaran R: Shape-controlled Au particles for InAs nanowire growth. Nano Lett 2012, 12: 315–320. 10.1021/nl2036035View Article
- Hannon JB, Kodambaka S, Ross FM, Tromp RM: The influence of the surface migration of gold on the growth of silicon nanowires. Nature 2006, 440: 69–71. 10.1038/nature04574View Article
- Jianwei Z, Lirong Q, Yong Z, Yonghao H, Qing G, Lide Z: Catalytic growth of cubic phase ZnO nanowires with jagged surface. Micro Nano Lett 2010, 5: 336–339. 10.1049/mnl.2010.0126View Article
- Jiang W, Seungyong L, Reddy VR, Manasreh MO, Weaver BD, Yakes MK, Furrow CS, Kunets VP, Benamara M, Salamo GJ: Photoluminescence plasmonic enhancement in InAs quantum dots coupled to gold nanoparticle. Mater Lett 2011, 65: 3605–3608. 10.1016/j.matlet.2011.08.019View Article
- Guang Z, Fengfang S, Tian L, Likun P, Zhuo S: Au nanoparticles as interfacial layer for CdS quantum dot-sensitized solar cells. Nanoscale Res Lett 2010, 5: 1749–1754. 10.1007/s11671-010-9705-zView Article
- Catchpole KR, Polman A: Design principles for particle plasmon enhanced solar cells. Appl Phys Lett 2008, 93: 191113(1)-191113(3).View Article
- Jiang W, Mangham SC, Reddy VR, Manasreh MO, Weaver BD: Surface plasmon enhanced intermediate band based quantum dots solar cell. Sol Energy Mater Sol Cells 2012, 102: 44–49.View Article
- Zhang YF, Wang YF, Chen N, Wang YY, Zhang YZ, Zhou ZH, Wei LM: Photovoltaic enhancement of Si solar cells by assembled carbon nanotubes. Nano-Micro Lett 2010, 2: 22–25.View Article
- Jiunn-Woei L, Huang-Chih C, Mao-Kuen K: Plasmonic Fano resonance and dip of Au-SiO2-Au nanomatryoshka. Nanoscale Res Lett 2013, 8: 468(1)-486(8).
- Jian Hua Y, Elder KR, Hong G, Martin G: Theory and simulation of Ostwald ripening. Phys Rev B 1993, 47: 14110–14125. 10.1103/PhysRevB.47.14110View Article
- Alloyeau D, Oikawa T, Nelayah J, Wang G, Ricolleau C: Following Ostwald ripening in nanoalloys by high-resolution imaging with single-atom chemical sensitivity. Appl Phys Lett 2012, 101: 121920(1)-121920(3).View Article
- Zhenyu Z, Lagally MG: Atomistic processes in the early stages of thin-film growth. Science 1997, 276: 377–383. 10.1126/science.276.5311.377View Article
- Abraham DB, Newman CM: Equilibrium Stranski-Krastanow and Volmer-Weber models. Europhysics Lett 2009, 86: 16002(p1)-16002(p4).View Article
- Sui M, Li MY, Kim ES, Lee JH: Annealing temperature effect on self-assembled Au droplets on Si (111). Nanoscale Res Lett 2013, 8: 525. 10.1186/1556-276X-8-525View Article
- Lei G, Yusuke H, Ming-Yu L, Jiang W, Sangmin S, Sang-Mo K, Eun-Soo K, Wang ZM, Jihoon L, Salamo GJ: Observation of Ga metal droplet formation on photolithographically patterned GaAs (100) surface by droplet epitaxy. IEEE Trans Nanotechnol 2012, 11: 985–991.View Article
- Rijnders G, Blank DHA: Pulsed Laser Deposition of Thin Films: Applications-Led Growth of Functional Materials, Chapter 8. USA: Wiley-Interscience, USA; 2007:179–180.
- Jihoon L, Zhiming W, Yusuke H, Eun-Soo K, Namyoung K, Seunghyun P, Cong W, Salamo GJ: Various configurations of In nanostructures on GaAs (100) by droplet epitaxy. Cryst Eng Comm 2010, 12: 3404–3408. 10.1039/c0ce00057dView Article
- Ziad Y, Abu W, Wang ZM, Lee JH, Salamo GJ: Optical behavior of GaAs/AlGaAs ring-like nanostructures. Nanotechnology 2006, 17: 4037–4040. 10.1088/0957-4484/17/16/007View Article
- Lee JH, Wang ZM, Black WT, Kunets VP, Mazur YI, Salamo GJ: Spatially localized formation of InAs quantum dots on shallow mesa- and trench patterns regardless of crystallographic directions. Adv Funct Mater 2007, 17: 3187. 10.1002/adfm.200700066View Article
- Lee JH, Wang ZM, Kim ES, Kim NY, Park SH, Salamo GJ: Self-assembled InGaAs tandem nanostructures consisting a hole and pyramid on GaAs (311)A by droplet epitaxy. Phys Status Solidi (a) 2010, 207: 348. 10.1002/pssa.200925406View Article
- Lee JH, Sablon K, Wang ZM, Salamo GJ: Evolution of InGaAs quantum dot molecules. J Appl Phys 2008, 103: 054301. 10.1063/1.2890149View Article
- Wang ZM, Seydmohamadi S, Lee JH, Salamo GJ: Surface ordering of (In, Ga)As quantum dots controlled by GaAs substrate indexes. Appl Phys Lett 2004, 85: 5031. 10.1063/1.1823590View Article
- Biegelsen DK, Bringans RD, Northrup JE, L E : Surface reconstructions of GaAs(100) observed by scanning tunneling microscopy. Phys ReV B 1990, 41: 5701–5711. 10.1103/PhysRevB.41.5701View Article
- Laukkanen P, Kuzmin M, Perälä RE, Ahola M, Mattila S, Väyrynen I: Electronic and structural properties of GaAs(100) (2 × 4) and InAs(100) (2 × 4) surfaces studied by core-level photoemission and scanning tunneling microscopy. J Phys ReV B 2005, 72: 045321.View Article
- Jiang W, Wang ZM, Li AZ, Shibin L, Salamo GJ: Surface mediated control of droplet density and morphology on GaAs and AlAs surfaces. Phys Status Solidi (RRL)-Rapid Res Lett 2010, 4: 371–373. 10.1002/pssr.201004402View Article
- Duke CB, Mailhiot C, Paton A, Kahn A, Stiles K: Shape and growth of InAs quantum dots on high-index GaAs(113)A, B and GaAs(2 5 11)A, B substrates. J Vac Sci Technol A 1986, 4: 947–952. 10.1116/1.573762View Article
- Sakong S, Du YA, Kratzer P: Atomistic modeling of the Au droplet–GaAs interface for size-selective nanowire growth. Phys ReV B 2013, 88: 155309.View Article
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/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited.