Metal and semiconductor nanoparticles display fascinating size-dependent structural, electronic, optical, magnetic, and chemical properties, which make them promising materials to be tailored and functionalized as fundamental building blocks for emerging nanotechnology applications. [1,2] Because of the strong dependence of nanoparticle properties on their quantum-scale dimensions, the synthesis of nanoparticles with a small size and shape variation is of key importance. At present, size-, shape-, composition-, and surface-chemistry-controlled nanoparticles can be synthesized by colloidal-solution methods for a wide range of materials. [3,4] Furthermore, strategies have been developed in which monodispersed nanoparticles can form self-assembled, long-range nanoparticle lattices (2D and 3D) under appropriate conditions. [1,2,5,6] The next important challenge for emerging nanotechnological applications (chemical and biological sensing, electronics, optoelectronics) is to perform controlled and hierarchical self-assembly of monodispersed nanoparticles from the solution phase into ordered and specifically designed nanoparticle structures immobilized on solid-surface templates. In this paper, we report an approach for controlled assembly of metal (Au) and semiconducting (CdSe/ZnS core/shell) thiol-terminated nanoparticles onto electrically patterned Si 3 N 4 /SiO 2 /Si (NOS) electret films with an unprecedented resolution.In the past few years, several important breakthroughs in scanning-probe-based lithographic techniques using tip-induced local electrochemical reactions of self-assembled monolayers (SAMs) [7][8][9][10] or tip-induced local-transport processes, such as dip-pen nanolithography, [11,12] were developed for fabricating surface templates, which can be used to assemble nanoparticles on solid supports. In these techniques, the patterning process is realized by molecular reaction or transport through a water meniscus that naturally occurs between the tip and sample under ambient conditions. Therefore, the typical resolution and writing speed of such techniques is controlled by parameters such as probe scan speed, temperature, humidity, and molecule type. Furthermore, the reaction or transport rate is limited by the reaction or ink-transport process. As a result, these types of lithographic mechanism limit the line-writing speed to the range 0.1-10 lm s -1 and the dotwriting time to the range of a few milliseconds to tens of seconds per dot (size-dependent) under ambient conditions. [7][8][9][10][11][12] Recently, electrostatic-force-based assembly of nanoparticles has been proposed as a general, precise, and reliable methodology for such purposes. [13][14][15][16][17][18][19][20][21][22] In the most direct type of electrostatic-force-based assembly, charge patterns are created by scanning-probe or microcontact charging techniques onto electret materials via electron-or hole-tunneling processes. [16][17][18][19][20] As the electret materials can retain electric charge or polarization for a long time, these ch...

Self-assembled hexagonal Au particle networks, 2–12 μm in cell size, on silicon have been achieved by a simple method. Honeycomb structure of Au nanoparticles on silicon was drop cast from the Au nanoparticle solution under appropriate concentration, evaporation rate, substrate temperature, and humidity. Hexagonal networks with discrete Au particles were generated in samples annealed in N2 ambient. Two-step annealing, i.e., annealing at 400 °C followed by annealing at 1000 °C for 1 h each was found to be effective to improve the regularity of the Au particle network. As the cell size can be adjusted by the tuning of the deposition conditions, the scheme promises to be an effective patterning method without complex lithography.

Hierarchical growth of silicate nanowires on individual Au particles in self-organized hexagonal Au particle networks has been achieved by appropriate control of annealing conditions in N2 ambient. Cathodoluminescence data showed that the silicate nanowires emit light with a wavelength of 415nm. The scheme to form the regular Au particle network offers an effective and economical means to produce a universal template to grow functional structures without complex lithography.

Long-range order of uniform in size and regular in shape 2D arrays of Au@TOAB-DT nanoparticles (4.9 nm) were formed by a displacement reaction of the outer-shells from tetraoctylammonium bromide (TOAB) to dodecanethiol (DT) molecules at room temperature. The displacement reaction has utilized both superior size and shape control of Au@TOAB nanoparticles and uniform dispersion capability of Au@DT nanoparticles to achieve an extraordinarily large in extent (3 µm × 3 µm) regular nanoparticle lattice structure.Self-assembled NiSi quantum dot arrays have been grown on relaxed epitaxial Si 0.7 Ge 0.3 on (001)Si. The formation of the one-dimensional ordered structure is attributed to the nucleation of NiSi nanodots on the surface undulations induced by step bunching on the surface of SiGe film owing to the miscut of the wafers from normal to the (001)Si direction. The two-dimensional, pseudo-hexagonal structure was achieved under the influence of repulsive stress between nanodots.

Long-range order, uniform in size, and regular in shape two-dimensional (2-D) arrays of core-shell structure Au nanoparticles have been synthesized. A reaction involving the displacement of the outer shells from tetraoctylammonium bromide (TOAB) to dodecanethiol (DT) molecules was used to form Au@TOAB-DT nanoparticles at room temperature (RT). The displacement reaction has used both superior size and shape control of Au@TOAB nanoparticles and uniform dispersion capability of Au@DT nanoparticles to achieve an extraordinarily large in extent (3 µm ϫ 3 µm), regular nanoparticle lattice structure. From ultraviolet (UV)-visible spectra, it was inferred that the interaction between the inner core and outer shell of Au@TOAB nanoparticles is weaker than that of Au@TOAB-DT and Au@DT samples. As a result, the ability of the TOAB outer shell to protect the Au@TOAB nanoparticles is weaker so that the system is more prone to agglomerate. On the other hand, the strong interactions between the inner core and outer shell for Au@TOAB-DT and Au@DT nanoparticles led to a predominantly 2-D structure.