Fabrication of large UV transmission blazed gratings for slitless spectral sky survey

Slitless spectral sky survey is a critical direction of international astronomical research. Compared with ground-based sky survey, space-based sky survey can achieve full-band observation, and its imaging quality and resolution capability are restricted by the efficiency and size of dispersive elements. Transmission blazed gratings are often used as the dispersive elements in the UV band. Holographic interference lithography produces the photoresist mask of a grating, and the ion beam etching vertically transfers the pattern to the substrate to form the SiO2 mask of a grating. To reduce the effect of ion beam divergence on the uniformity of the groove shape, the grating mask is etched tilted by the ion beam passing through a narrow slit to obtain a blazed grating with consistent structural parameters. Moreover, two-dimensional scanning of the sample stage enables the etching of large-size samples. A UV transmission blazed grating with a linear density of 333 lines mm−1, a blazing angle of 11.8°, and a dimension of 99.2mm × 60.0mm × 6.0mm was successfully fabricated with an average diffraction efficiency of 66%, a PV diffraction wavefront of 0.169λ (λ = 632.8 nm) and low stray light.

Постростовые технологии каскадных фотоэлектрических преобразователей на основе A-=SUP=-3-=/SUP=-B-=SUP=-5-=/SUP=--гетероструктур

Investigation and development of the post-growth technology for fabricating multi-junction photovoltaic converters based on GaInP/GaInAs/Ge heterostructure has been carried out. Antireflection coating, ohmic contacts and mesa-structure forming stages have been reviewed. The technology of n+-GaAs contact layer etching with the help of plasma-chemical, liquid and ion-beam etching has been investigated. Antireflection coefficient of radiation from the heterostructure with TiOx/SiO2 (x close to 2) antireflection coating surface was less then 3% in wavelength range 450-850 nm. The value of contact resistance for n- and p-type conductivity was 3E−5 − 3E−6 ohm · cm2, the decrease of photosensitive region shading degree at increased bus-bar conductivity has been archived. The mesa-structure surface current leakage decreased to the value of E-9 A at voltage less then 1 V.

Neutral Dissociation of Pyridine Evoked by Irradiation of Ionized Atomic and Molecular Hydrogen Beams

The interactions of ions with molecules and the determination of their dissociation patterns are challenging endeavors of fundamental importance for theoretical and experimental science. In particular, the investigations on bond-breaking and new bond-forming processes triggered by the ionic impact may shed light on the stellar wind interaction with interstellar media, ionic beam irradiations of the living cells, ion-track nanotechnology, radiation hardness analysis of materials, and focused ion beam etching, deposition, and lithography. Due to its vital role in the natural environment, the pyridine molecule has become the subject of both basic and applied research in recent years. Therefore, dissociation of the gas phase pyridine (C5H5N) into neutral excited atomic and molecular fragments following protons (H+) and dihydrogen cations (H2+) impact has been investigated experimentally in the 5–1000 eV energy range. The collision-induced emission spectroscopy has been exploited to detect luminescence in the wavelength range from 190 to 520 nm at the different kinetic energies of both cations. High-resolution optical fragmentation spectra reveal emission bands due to the CH(A2Δ → X2Πr; B2Σ+ → X2Πr; C2Σ+ → X2Πr) and CN(B2Σ+ → X2Σ+) transitions as well as atomic H and C lines. Their spectral line shapes and qualitative band intensities are examined in detail. The analysis shows that the H2+ irradiation enhances pyridine ring fragmentation and creates various fragments more pronounced than H+ cations. The plausible collisional processes and fragmentation pathways leading to the identified products are discussed and compared with the latest results obtained in cation-induced fragmentation of pyridine.

Research of FIB local milling processes for creation of nanosized field emission structures

The paper presents the results of experimental studies of the influence of the main parameters of a focused ion beam (FIB) during surface profiling on the accuracy of transfer of a pattern to a silicon substrate to create nanoscale field emission structures. In this work, the optimal FIB currents are determined, introducing a minimum amount of distortions during the formation of structures of various sizes. The possibilities of the method of local ion-beam etching of structures in a wide range from 0.1 to 2 μm are shown. The prospects of using this technology for the creation of field emission structures have been demonstrated. It is determived the current-voltage characteristic of the fabricated field-emission cells with a threshold voltage of the onset of emission of ∼ 2.5 V and a maximum current of 300 nA at 30 V.