Vladislav Dřínek

IR laser-induced reactive ablation of silicon monoxide in hydrogen and water atmosphere

TEA CO2 laser induced ablation of solid amorphous silicon monoxide in H2 and H2O atmosphere results in deposition of hydrogenated SiOx films, which reveals that ablated silicon monoxide fragments are reactive towards H2 and H2O. The films analyzed by FTIR and XP spectroscopy are revealed as rich in H, composed of Si0 and several SixOyHz configurations and containing both Si–OH and Si–H bonds. The films produced in H2O have (Si)H mostly bonded in the (O3)Si–H unit and those produced in H2 have H attached to Si which is bonded to 1–3 oxygen atoms.

IR laser-induced decomposition of disiloxane for chemical vapour deposition of poly(hydridosiloxane) films

Continuous-wave CO2-laser-induced gas-phase decomposition of H3SiOSiH3, dominated by elimination and polymerization of transient silanone H2SiO and yielding silane and hydrogen as side-products, represents a convenient process for chemical vapour deposition of poly(hydridosiloxane) films. Copyright

TEA CO2 pulsed laser deposition of silicon suboxide films

Abstract The growth of silicon suboxide films ( SiO x , x ) by pulsed TEA CO2 laser ablation of SiO target at low substrate temperatures (⩽425°C) in vacuum is reported. To understand the wavenumber shift of the asymmetric stretching band ν(Si–O) with temperature the subbands obtained by fitting of infrared spectra using X-ray photoelectron data were located and studied. The structural properties of deposited films were investigated. Since relative concentration of oxygen is almost constant and relative concentration of elemental silicon and SiO2 in the films increases with the substrate temperature the shift of asymmetric stretching band ν(Si–O) can be explained by rearrangement and relaxation processes in the films and/or by moving of oxygen atoms from Si2O, SiO and Si2O3 to Si and SiO2 silicon species creating the films.

IR laser photosensitized decomposition of trimethyl(2-propynyloxy)silane for chemical vapour deposition of polydimethylsiloxane phases

Abstract The infrared laser-photosensitized (SF 6 ) decomposition of trimethyl(2-propynyloxy)silane (TMPSi) induced by TEA CO 2 laser affords a multitude of unsaturated hydrocarbons and a solid polydimethylsiloxane phase. This process of chemical vapour deposition in which all the silicon of the parent is completely utilised in the formation of the solid phase is briefly compared with UV laser photolysis of TMPSi.

IR LASER-INDUCED DECOMPOSITION OF TETRAVINYLSILANE FOR CHEMICAL VAPOUR DEPOSITION OF SI/C/H MATERIALS

Abstract The infrared multiphoton decomposition of tetravinylsilane in flow and batch reactors induced by a TEA CO2 laser leads to the formation of gaseous ethyne (the major product), ethene, buta-1,3-diene and a solid a-SiC:H deposit, the composition of which depends on the reactor used and the temperature of the substrate. Prolonged exposure of the films to air leads to the incorporation of oxygen.

From shelled Ge nanowires to SiC nanotubes

Shelled germanium nanowires up to 100 nm in diameter and several micrometers in length were prepared by low pressure chemical vapor deposition (LPCVD) of tris(trimethylsilyl)germane (SiMe(3))(3)GeH. Vapors of the precursor were deposited on tantalum substrates in an oven at 365 degrees C. Subsequently, the products were annealed at 700 degrees C in vacuum. The wires consist of a crystalline Ge core surrounded by a two-layer jacket. The presence of hexagonal Ge in the core was documented in some of the nanowires. The inner jacket is formed by amorphous germanium, the outer part by an Si/C material. By annealing at 900 degrees C, germanium in the core is expelled and nanotubes formed by the Si/C material remain. The samples were studied by SEM, HRTEM, EDX, FTIR and Raman spectroscopy, and the XRD technique.

IR laser induced CVD of SiO2 phases from triethoxysilane and tetraethoxysilane

Abstract CO 2 laser induced decomposition of triethoxysilane and tetraethoxysilane in the gas phase affords a number of gaseous products and SiO 2 films that incorporate all the silicon from the parent compounds. The process has been examined in batch and flow reactors at different temperatures of substrates to assess its potential for CVD of SiO 2 . FTIR and XPS analysis of the films reveals a small contamination by H and C, which decreases with increasing substrate temperature. The occurrence of elemental silicon in the SiO 2 films produced from triethoxysilane reflects a hitherto unobserved mode of Si formation.

INFRARED PHOTOLUMINESCENCE SPECTRA OF PBS NANOPARTICLES PREPARED BY LANGMUIR–BLODGETT AND LASER ABLATION METHODS

We optimized the optical setup originally designed for the photoluminescence measurements in the spectral range 400‒1100 nm. New design extends the spectral range into the near infrared region 900‒1700 nm and allows the colloidal solutions measurements in cuvettes as well as the measurements of nanoparticles deposited in the form of thin films on glass substrates. The infrared photoluminescence spectra of the PbS nanoparticles prepared by the Langmuir–Blodgett technique show the higher photoluminescence intensity and the shift to the shorter wavelengths compared to the infrared photoluminescence spectra of the PbS nanoparticles prepared by the laser ablation from PbS target. We aslo proved the high stability of PbS nanoparticles prepared in the form of thin layers.

IR laser ablation of silicon monoxide in gaseous methanol and hydrocarbons: deposition of polyoxocarbosilane

TEA CO2 laser-induced (thermal) ablation of amorphous silicon monoxide in gaseous methanol and hydrocarbon (ethane, ethene, ethyne) results in chemical vapour deposition of solid nano-structured polyoxocarbosilane coatings. The coatings analyzed by FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS) are revealed as composed of different SikOlHmCn configurations and containing SiOCHx, SiCHx and SiH bonds (ablation in methanol) or SiH and SiCHx bonds (ablation in hydrocarbons). The enrichment by H and CHx groups is dependent on methanol and hydrocarbon pressure. The incorporation of carbon during the SiO ablation in hydrocarbons grows in the series ethane

IR laser induced chemical vapour deposition of carbonaceous phases from 3-butyn-2-one

Abstract CO2 laser induced decomposition of 3-butyn-2-one in the gas phase results in the deposition of carbonaceous films composed of a graphitic and monohydrogenated carbon, in which H is dominantly bonded to sp3 sites. The films incorporate oxygen in superficial layers. The technique is suitable for preparation of thin C-based films at low substrate temperatures.