Here we report a facile and versatile procedure for the preparation of semiconductor-metal hybrid nanoparticles with an anisotropic structure consisting of bismuth telluride (Bi2Te3) and gold (Au) (or silver (Ag)) nanoparticles. We simply added flake-shaped Bi2Te3 nanoparticles (Bi2Te3 nanoflakes) and trisodium citrate to an aqueous Au or Ag precursor solution heated to boiling. The edge part of the Bi2Te3 nanoflake was preferentially modified with Au or Ag nanoparticles, and the Bi2Te3-Au hybrid nanoparticles had a broad peak of light absorption around the visible region and a higher thermoelectric power factor than ordinary Bi2Te3 nanoflakes. Because of the simplicity of the procedure, the hybrid nanoparticles are expected to be used as a new class of functional materials in the large scale production.

An epitaxial shell of cadmium sulphide is grown on lead sulphide quantum dots in order to reduce the concentration of surface defects. Thin solid films of these core/shell materials are found to have low carrier concentrations due to effective surface passivation which reduces the number of dangling bonds. In this paper PbS/CdS is used as a quasi-intrinsic layer in p-i-n photovoltaic devices where PbS acts as the p-layer and ZnO the n-layer. By studying different permutations of these layers and the degree of PbS p-type doping by annealing we optimise fill factor and open-circuit voltage.

The emission of crystalline silicon nanoparticles as well as nanowires can be tuned by varying their diameters. The diameter selection is achieved via a difficult chemical procedure that necessitates filtration which cannot be easily scaled up. Herein, we report a novel approach for producing and tuning the emission of freestanding colloidal of amorphous porous silicon nanoparticles (which should not be confused with bulk amorphous silicon nor with porous silicon) via a controlled oxidation without relying on size of nanoparticles. This oxidation increases local strain in the disordered network that causes orbital interactions which modifies the band-gap but a new hybridization.

Nanosphere lithography (NSL) is a technique capable of creating large-area arrays of small objects with tailor-made shapes. Here we present an algorithm, which simulates the shape and morphology of nanoparticles produced via NSL in combination with physical vapor deposition from variable angles. The key idea is based on a ray-tracing technique. Mask clogging effects have a major influence on the shape of resulting nanoobjects and are therefore taken into account. In addition, we implemented a metaball concept for the precise description of thermally modified masks. The calculated results are compared exemplarily with atomic force microscopy (AFM) data of experimentally fabricated nanostructures.

InP membranes have been bonded both oxide free and oxide mediated onto a Si substrate. The mechanical responses of the obtained thin (0.4 µm) membranes could be tested by nanoindentation and compared. Delamination of the membrane was observed to occur when the indenting load reached 55 mN for an oxide mediated bonded structure and 80 mN for an oxide free bonded one. Weibull analysis of these events yielded a modulus m of magnitude 6 to 10, indicating that delamination fracture is relatively predictable with a stronger interface obtained in oxide free approach. Delamination of the membrane is the result of constraint of plastic flow by the InP/Si interface. Membrane rotation is induced and increases with the indentation load, until it is sufficient to induce and propagate an interfacial crack.

Area-selective electroless deposition of gold nanostructures on a 6H-SiC substrate is demonstrated. Gold nanostructures selectively grow on a focused ion beam (FIB)-irradiated area on the 6H-SiC substrate when the substrate is exposed to a pure HAuCl4 aqueous solution. The nucleation of gold was more favorable on the Si face than on the C face. Quantitative evaluation of the amount of gold grown both on SiC and silicon is conducted to discuss the growth of gold, where silicon is a substrate we used in our previous study on this method. We reveal the mechanism of the growth of gold nanostructures as follows: Dangling bond defects formed in the FIB-irradiated area initiate the nucleation of gold by reducing Au ions in the solution at the surface. Once the SiC-gold or the silicon-gold boundary, which meets the Schottky contact condition, has formed, electrons in the non-FIB-irradiated region under/around the FIB-irradiated one also reduce Au ions on the gold surface through the boundary.

Nanoscale systems combining colloidal quantum dots with plasmonic antennas will pioneer the development of novel nanodevices with tailored optical features for a wide range of applications. The interactions between such nanoparticles strongly depend on the particular distance. We propose the use of an atomic force microscope (AFM) to image and to position quantum dots with respect to plasmonic particles. Additionally, we analyze the arrangements with several optical characterization methods, such as confocal microscopy, fluorescence microscopy and superresolution optical fluctuation imaging (SOFI). These methods support each other and improve the AFM manipulation technique. The AFM tip is perfectly aligned to a focused laser by detecting the Raman signal of the silicon tip. Thus ultimately, we can simultaneously use the topography information with a spatial resolution in the range of the nanoparticle sizes and cross-correlate it with the optical characterization methods.

We present a strain-free, self-assembled GaAs nanodots on GaAs(001) surfaces. Nanodots are studied by atomic force microscopy and field emission scanning electron microscopy. Nanodots self-assemble on the GaAs surface when two laser pulses overlap on the surface interferentially. Their stoichiometry is characterized by energy dispersive X-ray spectroscopy in the electron microscope. For the stoichiometry study, electrons with voltages less than 5 kilovolts were used to produce the characteristic X-rays from dots in order to enhance the surface sensitivity. The stoichiometric analysis indicates that the nanodots’ relative composition ratio of Ga over As reaches to that of GaAs substrate when the dot size becomes smaller than 100 nm. The chemical analysis suggests a novel route of strain-free semiconductor nanodots.

In this paper we present fast response processes in dye doped liquid crystal cell with ZnSe layers on electrodes. Two-wave mixing and grating monitoring experiments were performed to characterize this liquid crystal system. With the help of photoconductive layers, the response time was reduced to a few milliseconds, which improved further the response rate in liquid crystal photorefractive system. A peak in response time versus applied voltage and unexpected oscillations in diffraction efficiency dynamics were observed, which implies unconventionally complex charge dynamics associated with SPPs excited at one of the photoconductive layer/liquid crystal interfaces.

The highlight of this work is the synthesis of copper sulfide nanocrystals by a simple one-pot colloidal process, and the study of its electrochemical, electrical and morphological properties. Nanocrystals of Cu1.8S of about 15-30 nm were obtained at a temperature of 240°C under an argon atmosphere. The colloidal solution of the nanocrystals was analyzed by cyclic voltammetry. Agreeing to the values of EOx and ERedvs. SCE, and the average of three samples the HOMO and LUMO levels are 6.16 and 4.27 eV, respectively, the calculated HOMO – LUMO (Eg) is 1.89 eV. The Eg value, differs of that value obtained from Kubelka-Munk equation (1.7 eV). The photocurrent vs. time results showed that the Cu1.8S/Cu junction is photosensitive and could be used as absorbing material. The morphology and the topography of the film were analyzed by SEM and AFM techniques. Irregular agglomeration of nanocrystals was observed and a roughness of about 194 nm.

We herein report the optical and cytotoxicity properties of highly luminescent water soluble mercaptopropanoic acid (MPA) capped CdTe/CdSe core shell nanoparticles (NPs). The synthesis of the CdTe/CdSe NPs was carried out via a simple, one pot and economical route, involving the use of greener materials under ambient environment in the absence of an inert atmosphere. The temporal evolution of the size and optical properties of the nanomaterials was investigated by varying the reaction time and stability of the as-synthesised material at pH 12. The as-synthesised nanomaterials were characterised using UV-vis absorption and photoluminescence (PL) spectroscopy. The nanoparticles obtained were of high quality with high absorption and emission features. Addition of Se precursor to produce CdSe layer on the CdTe NPs core surface resulted in significant red shirt of both the absorption and emission maxima. The stability study showed that the emission maximum peak positions and FWHM remain the same with increase in emission intensity for all the NPs during the aging period. The cytotoxicity assay showed very high cell viability for the CdTe/CdSe NPs produced at 7 h compared with those produced at 30 mins as the concentration increased from 0.1 to 60 ug/ml. The lower cytotoxicity at the higher reaction time was attributed to the higher stability of the material and hence lower release of Cd2+.

We herein report the synthesis of highly-fluorescent CdSe/ZnS core-shell quantum dots (QDs) nanophosphors via a simple, non-phosphine and one pot synthetic method in the absence of an inert atmosphere. The as-prepared nanocrystallites were characterized by Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-vis) and photoluminescence spectroscopy, transmission electron microscopy (TEM) and high resolution TEM (HRTEM). The obtained CdSe/ZnS QDs were of high quality with sharp absorption peaks, bright luminescence, narrow emission width and high PL quantum yield (up to 74 %) without any size sorting. The structural analysis showed that the as-synthesised QDs are small and spherical in shape with narrow size distributions while the presence of the lattice fringe in the HRTEM image confirmed the crystallinity of the material. The dispersion of the obtained core-shell QDs in PMMA matrix resulted in the fabrication of highly fluorescent PMMA- CdSe/ZnS core shell QDs polymer nanocomposite film.

We study how the period of transient thermal gradient impacts on morphologies of nanostructures on the Si(001) surface. Strain-free, self-assembled nanodots as well as periodic nanowires are fabricated directly on Si(001) surfaces by applying high power laser pulses on the surface interferentially. The morphologies of the nanostructures are studied by atomic force microscopy. Generally, the laser irradiated surfaces show nanowires but nanodots are also observed. The nanowire width increases with interference period. The narrowest nanowires observed have the width smaller than 50 nm, which is four times smaller than the interference period while the nanodots have a base width of 43 nm and height of 8 nm.