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We report on the fabrication process of SiO2 templates with periodic sub-100 nm patterns by electron-beam (e-beam) lithography followed by reactive ion etching. One-dimensional and two-dimensional periodic patterns were defined in 350 nm polymethylmethacrylate resist by e-beam lithography, and then transferred into 100 nm SiO2 layers which were coated on GaAs or GaN/sapphire substrate. Patterns including line arrays and square/hexagonal hole arrays were obtained in the SiO2 layers with sizes ranging from 100 nm to 52 nm in width or diameter. A pattern size deviation of less than 4% in a hole array of 100 µm by 100 µm was achieved. The patterned SiO2 layers can serve as templates for the growth of periodic III–V semiconductor nanostructures. In this work, periodic InGaN nanowires and nanodots with high optical quality have been fabricated successfully by using the SiO2 templates on GaN/sapphire.

Ultrathin films of Eu 3+ doped Y2O3 were deposited onto alumina nanoparticles using a unique solution synthesis method. The surface structure, composition, and morphology of the thin films deposited were analysed using high resolution transmission electron microscopy (TEM) and high angle annular dark field scanning TEM imaging and energy dispersive x-ray measurements. The films deposited were extremely thin, on the order of 3–5 nm, and uniformly covered all the alumina nanoparticles. X-ray diffraction was used to investigate the phases and structures of the thin films deposited. At the heat treatment temperature of 600 ◦ C, cubic Y2O3 nanocrystals were found in the film while as-coated layers exhibited mainly amorphous features. As the heat treatment temperature increased to 750 ◦ C, the amorphous thin film became well crystallized. Optical properties of Eu 3+ doped Y2O3 films were characterized by fluorescence spectroscopy. Strong photoluminescence was observed in the sample annealed at 750 ◦ C, from the fluorescence of Eu 3+ ions in a well-crystallized film, consistent with the

The structural and electronic properties of Eu3+-doped Y2O3 films coated on spherical alumina nanoparticles are studied using transmission electron microscope, x-ray diffraction, and laser spectroscopic techniques. It is observed that the coated films crystallize at temperatures higher than 600°C and may be completely converted into a cubic Y2O3 nanocrystalline layer at 750°C. At 900°C, phase transition occurs between the outer coating layer and the inner core, and different types of crystalline nanophase can be obtained. In the materials that we prepared and studied, all possible crystallographic phases, including two of solid-state laser media, YAlO3 (YAP), and Y3Al5O12 (YAG), may be formed in the pseudo-binary Al2O3–Y2O3 nanosystem by controlling thermal annealing procedures from 600 to 900°C, a temperature region far below the conventional solid-state reaction temperature. The spectroscopic properties of Eu3+ in all the nanophases are characterized in comparison with those of their bulk counterparts.

The LB technique is an important way to obtain the ordered aggregate of nanometre-sized particles. However, with the usual LB technique only those particles capped by short-chain molecules (

We report the observation of periodical negative differential conductivity (NDC) in hydrogenated nanocrystalline silicon/crystalline silicon diode heterostructures by low-temperature current–voltage measurements. The NDC-related series of spike-like current peaks is found to result from the accumulation and depletion of electrons tunnelling through the nanodot layers in the neutral region. The observation has been further supported by the facts of onset-voltage blueshift, number variation in current peaks, and inter-Landau-level tunnelling in the temperature- and magnetic field-dependent experiments. We also discuss the differences between the present periodical NDC and the electric field domain in superlattice structures.