Investigation on Light Extraction Behavior of Surface Plasmon-Coupled Deep-Ultraviolet LED in Different Emission Directions

The light extraction behavior of an AlGaN-based deep-ultraviolet LED covered with Al nanoparticles (NPs) is investigated by three-dimensional finite-difference time-domain simulation. For the transmission spectra of s- and p-polarizations in different emission directions, the position of maximum transmittance can be changed from (θ = 0°, λ = 273 nm) to (θ = 0°, λ = 286 nm) by increasing the diameter of Al NPs from 40 nm to 80 nm. In the direction that is greater than the critical angle, the transmittance of s-polarization is very small due to the strong absorption of Al NPs, while the transmittance spectrum of p-polarization can be observed obviously for the 80 nm Al NPs structure. For a ~284 nm AlGaN-based LED with surface plasmon (SP) coupling, although the luminous efficiency is significantly improved due to the improvement of the radiation recombination rate as compared with the conventional LED, the light extraction efficiency (LEE) is lower than 2.61% of the conventional LED without considering the lateral surface extraction and bottom reflection. The LEE is not greater than ~0.98% (~2.12%) for an SP coupling LED with 40 nm (80 nm) Al NPs. The lower LEE can be attributed to the strong absorption of Al NPs.

Laser synthesis of nanocomposite hydrocarbon fuel and CARS diagnostics of its combustion flame

We report an analysis of diffusive combustion in oxygen of a composite fuel formed by the addition of aluminium nanoparticles (NPs) to isopropanol. The process of obtaining Al NPs consisted in laser fragmentation of initially large industrial NPs using radiation of a pulsed nanosecond neodymium laser. The size distribution of Al NPs was determined using a measuring disk centrifuge. The average nanoparticle size was 20 nm, which is confirmed by transmission electron microscopy data. A diagnostic system based on coherent anti-Stokes Raman scattering (CARS) was used to experimentally study the diffusive combustion of composite fuel. The temperature distributions were measured in two mutually orthogonal directions (along the flame and in the transverse direction) in pure isopropanol and in isopropanol with the addition of 0.15 wt % of Al nanoparticles.

Study of synthesis and combustion of composite fuels based on n-decane and Al nanoparticles

The article is devoted to the analysis of a diffusion combustion of a composite fuel (formed by an addition of non-oxidized aluminum (Al) nanoparticles (NP’s) to n-decane) with oxygen. The process of obtaining Al NP’s consisted of a laser fragmentation of initially large commercially produced NP’s (so called “Alex” with mean diameter is about 450 nm) in the solution of isopropanol. A final size distribution of NP’s was determined by a CPS DC2400 measuring disk centrifuge. The morphology of NP’s was characterized with the Transmission Electron Microscope (TEM) JEM-100C. The measured average diameter of NP’s was about 40 nm. In the final step of a preparation of a composite fuel an isopropanol was exchanged on n-decane. To characterize the composite fuel, diffusion combustion was used in combination with the laser diagnostic technique CARS. Temperature distributions along the x direction were measured at two values of distances from the nozzle. It has been shown that, for the fuel consistent of 0.1% mass concentration of Al NP’s in n-decane, the temperature at the distance equaled 14 mm downstream from the nozzle exit of a burner in the vicinity of the flame front was significantly higher (by 200–300 K) than that upon burning of pure n-decane.

Moiré Nanolithography Based on Ultrathin Anodized Aluminium Oxide Membranes

A new nanofabrication method for construction of complex superlattice structure with versatile super-periodicity is developed using the moiré fringe of anodized aluminium oxide (AAO) membranes. Two ultrathin AAO membranes with long-range order holes are stacked to form 2D moiré nanopatterns. Both rotational symmetry and the periodicity of the holes are modified by the relative spatial displacement between the superimposing layers. Using the membranes as metal evaporation masks, a wide assortment of complex Al nanostructures are fabricated by varying the misorientation angle of the two ultrathin AAO membranes. Highly ordered Al nanoparticles with different sizes, shapes, orientations, and arrangements on substrates are achieved, which are expected to give abundant surface plasmon mode.

Control and Modification of Nanostructured Materials by Electron Beam Irradiation

I have proposed a bottom-up technology utilising irradiation with active beams, such as electrons and ions, to achieve nanostructures with a size of 3–40 nm. This can be used as a nanotechnology that provides the desired structures, materials, and phases at desired positions. Electron beam irradiation of metastable θ-Al2O3, more than 1019 e/cm2s in a transmission electron microscope (TEM), enables the production of oxide-free Al nanoparticles, which can be manipulated to undergo migration, bonding, rotation, revolution, and embedding. The manipulations are facilitated by momentum transfer from electrons to nanoparticles, which takes advantage of the spiral trajectory of the electron beam in the magnetic field of the TEM pole piece. Furthermore, onion-like fullerenes and intercalated structures on amorphous carbon films are induced through catalytic reactions. δ-, θ-Al2O3 ball/wire hybrid nanostructures were obtained in a short time using an electron irradiation flashing mode that switches between 1019 and 1022 e/cm2s. Various α-Al2O3 nanostructures, such as encapsulated nanoballs or nanorods, are also produced. In addition, the preparation or control of Pt, W, and Cu nanoparticles can be achieved by electron beam irradiation with a higher intensity.