Optical nanogratings are widely used for different optical, photovoltaic, and sensing devices. However, fabrication methods of highly ordered gratings with the period around optical wavelength range are usually rather expensive and time consuming. In this article, we present high speed single-step approach for fabrication of highly ordered nanocomposite gratings with a period of less than 355 nm. For the purpose, we used commercially available nanosecond-pulsed fiber laser system operating at the wavelength of 355 nm. One-dimensional and two-dimensional nanostructures can be formed by direct laser treatment with different scan speed and intensity. These structures exhibit not only dispersing, but also anisotropic properties. The obtained results open perspectives for easier mass production of polarization splitters and filters, planar optics, and also for security labeling.
The compact negative ion source having a semiplanotron discharge geometry and the two independently heated LaB6 cathode inserts was developed and studied. The hot LaB6 cathode insert supports discharge ignition and operation at low hydrogen pressure, while the cold one provides the glow discharge concentration in its vicinity. The stable production of H− beams with the current density in the emission hole in the range of about 0.1 A/cm2 was obtained in the pure hydrogen discharge. Negative ion yield at the different parts of the composite source cathode was measured. It was maximal in the glow region. An enhanced H− yield was recorded due to discharge concentration near the LaB6 inserts. LaB6 with a decreased work function does not produce a sizable income of surface-produced negative ions to the beam, extracted from the pure hydrogen discharge. The use of LaB6 inserts as a reliable source of electrons to form the discharge simplifies the surface-plasma source use.
In this paper we demonstrate a nanofabrication technique based on local ion irradiation of silicon dioxide with a focused helium ion beam. The wet etching of silicon dioxide irradiated with a focused helium ion beam is described in a two-dimensional case both numerically and experimentally. We suggest a model for the etching process based on the distribution of ion induced defects in the irradiated material. The profile of the surface of the etched silicon dioxide is simulated and compared with the results from scanning electron microscopy. Fabrication of a suspended nanostring with a diameter of less than 20 nm by means of etching ion-irradiated material is demonstrated.
The optical characteristics of lead-free nanocrystals with a crystal structure of the double perovskite type with the chemical composition Cs2AgInCl6, doped with bismuth and coated with silicon dioxide were studied, and the possibility of their further application was shown. The optical properties of the nanocrystals under study are analyzed by absorption and luminescence spectroscopy, including those with time resolution. Images were obtained using a scanning electron microscope. The influence of the amount of silicon dioxide precursor addition on the optical properties and morphology of lead-free nanocrystals was established. It is shown that the observed broad photoluminescence band is associated with the occurrence of self-trapped excitons in such nanocrystals. To demonstrate the possibility of practical application of these nanocrystals a light-emitting device based on them was developed and constructed. The light emitting device has a wide emission spectrum close to warm white light. Keywords: LEDs, lead-free perovskites, double perovskites, nanocrystals, photoluminescence.
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