Fabrication of silicon grating structures using interference lithography and chalcogenide inorganic photoresist

Application of inorganic photoresist based on chalcogenide films for fabrication of submicrometer periodic relief on silicon wafers was investigated. For this purpose, technological process of resistive two-layer chalcogenide-Cr mask formation on a silicon surface was developed, and silicon anisotropic etching was optimized, too. This technology has been used for the fabrication of high-quality diffraction gratings on Si (100) surface with symmetric triangular and trapezium grooves and two-dimentional periodic structures. Relief parameters and diffraction properties of the obtained structures and their dependences on etching time were determine

Recording of high efficiency diffraction gratings by He-Ne laser

The investigation results of holographic diffraction gratings recording processes by radiation of helium-neon laser have been represented. Inorganic As₄₀S₂₀Se₄₀ photoresist treated by the newly developed selective etching solution was chosen as a registering media. Angular and spectral dependencies of grating diffractive efficiency absolute values were measured. A comparison of fabricated gratings characteristics with corresponding parameters of gratings recorded on As₄₀Se₆₀ photoresist was carried out. Numericall simulation of groove profiles inherent to holographic gratings made in various experimental conditions was performed. Shown is that photoresists based on As₄₀S₂₀Se₄₀ are suitable for production of high quality holographic optical elements

Optical study of thermally induced phase separation in evaporated SiOx films

SiOx thin films (x ~1.3) have been prepared by thermal vacuum evaporation of silicon monoxide. A thermally stimulated (annealling temperatures – 700 and 1000°C) structural transformation of the Si-O phase in the SiOx layers, which leads to the formation of amorphous and crystalline Si nanoinclusions, was investigated using photoluminescence and infrared spectroscopy. It is demonstrated that the heat treatment leads to the decomposition of molecular complexes of slightly oxidized Si and the formation of both Si clusters and molecular clusters containing heavily oxidized Si. The transformations of the oxide phase are almost completed after 5 min. of the thermal treatment. The films annealed at 700°C contain amorphous Si nanoclusters embedded into homogeneous SiO₁.₇₅ matrix (the volume share of amorphous Si phase is equal to ~17 vol.%). The films annealed at 1000°C represent Si nanocrystals (the volume share is equal to ~20 vol.%) surrounded by SiOx interface layers and embedded into SiO₂. Both types of samples - the ones with Si nanocrystals and with amorphous Si nanoinclusions – exhibit photoluminescence in visible and near infrared spectral range. PL peak is blueshifted and is 5 to 10 time more intense for amorphous as compared with crystalline nano-Si. The origin of the light emission may be related to electron-hole pairs recombination in amorphous nanoinclusions and carrier recombination through double Si=O bonds at the nc-Si – oxide matrix interface. Remove selecte

Paramagnetic defects related to photoluminescence in SiOx films

The correlation between the photoluminescence and paramagnetic defects is studied in SiOx films grown by vacuum thermal deposition and annealed at 750 ⁰C. The as-grown samples exhibit a wide structureless EPR line centered at g = 2.0040, which is explained by the presence of a variety of dangling bonds •Si = SiyO₃–y. The annealing at 750 ⁰C causes the formation of amorphous silicon inclusions in SiOx matrix, appearance of the photoluminescence peaked at ~ 1.8 eV and shift of the EPR line to the low field range. The latter implies the preferable annealing of the paramagnetic defects in the regions of the sample with higher concentration of oxygen. The optically detected magnetic resonance studies show that these defects are not responsible for the luminescence; they are the centers of nonradiative recombination, but the efficiency of photoluminescence quenching due to these defects is rather low

Effect of chemical and radiofrequency plasma treatment on photoluminescence of SiOx films

Effect of hydrogen radiofrequency plasma and chemical treatment on photoluminescence (PL) spectra of SiOx layers containing Si nanoparticles are investigated. Considerable PL intensity growth in the samples containing Si nanocrystals (nc-Si-SiOx) after plasma treatment is observed. The process saturates for time of 15 minutes. Chemical treatment in ammonia and acetone vapour before thermal annealing of SiOx layers leads to the considerable changes in PL spectra effecting both on the band shape and on the intensity. The possibility of controlled changes in PL spectra in nc-Si-SiO₂ layers is shown

Effect of low-temperature annealing on light-emitting properties of na-Si/SiOx porous nanocomposite films

The effect of low-temperature annealing on light emitting properties of naSi/SiOx porous column-like nanocomposite films has been studied. Influence of type of chemically active gas or inert ambient on PL characteristics is shown. Existence of metastable defects in such structures is shown. A temperature interval for healing the metastable defects is defined. Mechanisms to reduce a non-radiative recombination channel depending on the gas ambient are proposed

Recording of rainbow holograms using As₂Se₃ amorphous layers

The simple method of phase-relief rainbow master-hologram recording using the only laser has been developed. In this method at both recording steps (a normal transmission hologram and phase-relief sunlight-viewable master hologram recording) the same inorganic chalcogenide photoresist and the same postexposure one-stage treatment are used. It results in more simple and cheaper process of master hologram fabrication

Electron field emission from SiOx films

Efficient electron field emission from silicon flat cathode coated with SiOx film (x 0.3-0.5) was observed both before and after thermal (1000 °C) annealing with subsequent etching in HF solution. Oxide films were produced by silicon thermal evaporation in vacuum (10⁻⁵ Torr). Using optical spectroscopy in visible and infrared ranges, as well as AFM technique, structural features of these films were investigated. It was shown that initial SiOx film may be represented as SiOх (Si) composite (x 1.2). Thermal annealing causes further phase segregation in film material, and it is transformed into SiO₂ (Si) composite. During such a process, silicon grains size decreases and their density increases. The model of electron field emission from the surface of such films was proposed. It was supposed that limitation process of the current flow under high electric fields is connected with Fowler-Nordheim tunneling through barriers Si-SiOх-vacuum or Si-vacuum. Current peaks in emission I-V characteristics were explained in the framework of resonance tunneling mechanism. Investigated structures seems to be perspective for application as flat field cathodes in vacuum electronic devices and in flat panel field emission displays