Nanodot array

Synthesis of nanodot arrays using self-assembled niobium oxide nanopillar mask by reactive ion etching... 

The formation of nanostructures such as nanodot arrays has drawn a great attention due to the feasible applications in a variety of functional structures and nanodevices containing optoelectronic device, information storage, and sensing media [1-3]. The various methods such as self-assembled nanodots from solution onto substrate, strain-induced growth, and template-based methods have been proposed for the fabrication of nanodot arrays on a large area, [4-6]. However, most of these works can be applied to the small scale systems due to the limited material systems. 

In this report, the fabrication of Si nanodot arrays using niobium oxide nanopillars as an etching mask was performed by an inductively coupled plasma reactive ion etching (ICPRIE). 

The formation of Si nanodot arrays on a substrate was performed by ICPRIE of Si films using self-assembled niobium oxide pillars as an etching mask. The etch rates of niobium oxide pillars and Si films, and the etch selectivity of Si films to niobium oxide were investigated by varying etch parameters in a Ch/Ar gas. The main etch parameters used in this study were the concentration of CI2 gas, coil rf power, and dc-bias to substrate. 

In order to confirm the formation of nanodots, the fabricated nanodot arrays on a substrate were examined using energy dispersive spectroscopy (EDS). The EDS analysis of niobium oxide arrays on Si film before etching (Fig. 2(a)) was shown in Fig. 3(a). The Si peak as well as Nb and O peaks was observed because niobium oxide on Si film was so thin. 

Figures 3(b) and 3(c) were the EDS results of the etched nanodot arrays shown in Figs. 2(b) and 2(c). The EDS of Fig. 3(b) was almost identical to that of Fig. 3(a). It means that niobium oxide masks were still on Si film although the Si dots were formed. Fig. 3(c) was the EDS result of the nanodot arrays etched for longer etch time than Fig. 3(b). The Nb peak disappeared due to the increased etching and it was confirmed that the nanodots consisted of only Si. The diameters of Si nanodots were approximately 20 30 nm. It was demonstrated that the optimal etching condition could form close-packed and highly ordered Si nanodot arrays without niobium oxide mask. It is expected that this novel technique of forming...

Fig. 2. FESEM images of (a) niobium oxide arrays before etching, and of Si nanodot arrays etched for (b) 20 s and (c) 30 s at 20% CI2, 500 W coil rf power, 300 V dc-bias voltage and 5 mTorr gas pressure...

Secondly, we describe the site-selective introduction of a functional molecule, tetrakis-5,10,15,20-(4-carboxyphenyl)porphyrin (TCPP), into the microphase separation structure of a diblock copolymer film of PS-fo-P4VP. Since porphyrin derivatives show various functionalities such as sensitization, redox activity, and nonlinear optical effect, a polymer nanodot array containing a porphyrin at a high concentration would be applicable to a light-harvesing and charge transporting nanochannel. 

Similarly, monometallic Rh, Pd, and Au and bimetallic Pt-Rh and Pt-Pd nanowires were prepared in FSM-16 or HMM-1 by the photoreduction method [30,33,34]. The bimetallic wires gave lattice fringes in the HRTEM images, and the EDX analysis indicated the homogeneous composition of the two metals. These results show that the wires are alloys of Pt-Rh and Pt-Pd. Mesoporous silica films were also used as a template for the synthesis of uniform metal particles and wires in the channels [35,36]. Recently, highly ordered Pt nanodot arrays were synthesized in a mesoporous silica thin film with cubic symmetry by the photoreduction method [37]. The... 

Figure 5.16 Tapping-mode AFM image of a 25 Cu nanodot array on H-terminated p-Si(l 0 0), formed by nanoindentation. (Reproduced with permission from Ref. [72].)...

Fig. 12 SEM image of a a Ru04 stained PS-PLA film and b a NisoFe2o nanodot array formed from the resultant nanoporous PS template. Reproduced from [50]...

There are some unique examples of organic-inorganic hybrids in natural systems. Some kinds of protein possess inorganic components at their interior. Because such bio-originated hybrid structures have discrete size and composition, they can be used for preparation of fine mesoscopic structures. For example, ferritin, which is composed of 24 self-assembled peptide subunits and capable of including iron oxide, is a good candidate to fulfill this demand. Yamashita demonstrated use of a ferritin array for preparation of a mesoscopic nanodot array (Fig. 2.11 ).47 A Langmuir... 

Figure 2.11 Monolayer array of ferritin and conversion into a nanodot array.

Surface micelles of fluorinated amphiphiles have potential as templates for the elaboration of metallic nanodot arrays. Hexagonal arrays of gold and silver nanodots, a few nM in size, have been observed by AFM to form when a thin layer of metal was deposited through vacuum evaporation on a silicon wafer covered with hemimicelles of the F8H16 diblock (E. Charrault, P. Muller, M. Maaloum, M.P. Krafft, C. Petit, P. Petit, unpublished). 

Kawaji J et al (2005) Area selective formation of magnetic nanodot arrays on Si wafer by electroless deposition. J Magn Magn Mater 287 245-249... 

Masuda H, Satoh M (1996) Fabrication of gold nanodot array using anodic porous alumina as an evaporation mask. Jpn J Appl Phys 35 L126-L129... 

P.A. Kossyrev, A.J. Yin, S.G. Cloutier, D.A. Cardimona, D.H. Huang, P.M. Alsing, J.M. Xu, Electric field mning of plasmonic response of nanodot array in liquid crystal matrix. Nano Lett. 5, 1978-1981 (2005)... 

Depending on the coverage. You etal. [167] have recently been successful in achieving nanodot arrays or nanowire array of Pl/ErSii heterostructures. Reactive... 

Schematic of patterning of Pt/ErSi2 nanowire and nanodot array on silicon substrate.

Tiberto P, Boarino L, Celegato F, Coisson M, Enrico E, De Leo N, Vinai F, Allia P (2011) Synthesis of NigoFe20 and Co nanodot arrays by self-assembling of polystyrene nanospheres magnetic and microstructural properties. J Nanopart Res 13 4211... 

Huang J, Chiam SY, Tan HH, Wang S, Chim WK (2010b) Fabrication of sihcon nanowires with precise diameter control using metal nanodot arrays as a hard mask blocking material in chemical etching. Chem Mater 22 4111—4116... 

Recently, the characteristic phonon transport in nanostructures was analyzed by molecular dynamics simulations (Fang and Pilon 2011) in relation to the scaling laws for the thermal conductivity in nanodot array (Fang et al. 2012) and by hydrodynamic approach (Alvarez et al. 2010) for investigating the influence of PS porosity and pore size on the reduction in the thermal conductivity. 

The SMAs were also used to fabricate large-area ultrahigh-density nanoring arrays with sub-30 nm diame-ter. The nanodot arrays on silicon wafer, obtained from the porous thin film based on PS- -P4VP(HABA) SMA,... 

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