Bartosz Glebocki's research while affiliated with Polish Academy of Sciences and other places

The motivation for this contribution is the search for thin-film silicon oxycarbide (SiOC) materials suitable for modern electronics with good chemical/thermal stability, good barrier properties and conformal coverage, which can be deposited on rigid and flexible substrates, and whose surface can be organically functionalized. Two types of thin SiOC films of very different nature, such as polymer-like and ceramic-like, were fabricated by means of remote hydrogen microwave plasma chemical vapour deposition (RP-CVD) from 1,1,3,3–tetramethyldisiloxane (TMDSO). The RP-CVD coatings deposited on a silicon substrate were then modified by treatment with a direct radiofrequency (RF) plasma process induced in a mixture of argon and water vapour (Ar/H2O), which resulted in the surface activation through the formation of highly reactive silanol groups (Si–OH). In this process a silicon oxide layer (SiOx) was also formed, and its growth was examined by FTIR, XPS and ellipsometry. The growth of the SiOx structure reduces the film thickness of silicon oxycarbide. Activation of the film surface is completed in <10 s. In the next modification step, the RP-CVD films were silanized by immobilizing (3-aminopropyl)triethoxysilane (APTES). Attachment of APTES molecules to the activated surface of SiOC films was observed with the development of an additional layer of SiOx on the surface. The silanization with APTES vapour under nitrogen allowed the formation of 10 nm-thick condensate. The AFM microscopic examination showed that the deposited APTES layers are homogeneous without aggregates specific for conventional silanization from the solution. The final modification of RP-CVD films was achieved by functionalization with an organic fluorescent probe, which involves the covalent attachment of pyrene to amino group of APTES using hydroxyimide ester linkage (PyNHS). The results of the present study proved that the chemical functionalization of thin silicon oxycarbide films was achieved.

Amorphous hydrogenated silicon carbooxide (a-SiCO: H) films are coating materials of a complex structure composed of carbidic Si-C and oxide Si-O units. They have attracted much attention in recent times due to their excellent properties, such as high hardness and elastic modulus, low residual stress, low dielectric constant, and very low absorption coefficient. Taking into account that the contents of the chemical bonds or groups in the film are proportional to the integrated intensities of their IR bands, the relative integrated intensities of the component bands are assumed to provide quantitative information on the evolution of the a-SiCO:H film structure. The results of atomic force microscopy (AFM) examination of a-SiCO:H films revealed that their surface exhibited an excellent morphological homogeneity.

Gradient copolymer grafts of styrene and α-tert-butoxy-ω-vinylbenzyl-poly(glycidol ethoxyethyl ether) (PGLet), precursor of α-tert-butoxy-ω-vinylbenzyl-polyglycidol macromonomer (PGL) were prepared on silicon wafers via a surface-initiated activator generated by electron transfer radical polymerization (AGET ATRP). Silicon plates with previously attached 2-bromo-isobutyrate served as a macro-initiator for the AGET ATRP (activator generated by electron transfer) of styrene and PGLet. The copolymers' gradient P(S-co-PPGL) of composition and thickness was obtained by a simple method where the plates were slowly removed from reaction mixture using a step motor. PGLet was added continuously (dropwise) into the reactor during withdrawal of the plates from solution in order to increase the relative concentration of PGLet in polymerization mixture. A range of strategies of making grafts was tested. The plates with copolymers grafts were analysed by various techniques, like XPS, ellipsometry, FTIR spectroscopy. The results indicate that the AGET ATRP process is dependent to the styrene/PGLet macromonomer ratio in the polymerization mixture. Under optimal conditions, the addition of PGLet during polymerization and subsequent deprotection of hydroxyl groups of PGLet, permits to obtain plates with a novel copolymer layer with composition, thickness and wettability gradient. Plates with chemical composition of copolymer grafts gradient served as versatile supports with controlled hydrophilic/hydrophobic area and were suitable for tailored deposition of particles.

Amorphous, hydrogenated, silicon carbide (a-SiC:H) films are deposited in the remote hydrogen microwave plasma (RP-CVD) process using diethylsilane as a single-source precursor. The effect of substrate temperature (TS) on the kinetics of RP-CVD, chemical composition, structure, surface morphology, and properties (density, refractive index, and extinction coefficient) of the resulting a-SiC:H films is investigated. The TS dependence of film growth rate implies that RP-CVD is an adsorption-controlled process. The increase of TS from 30 °C to 350 °C causes the elimination of organic moieties from the film and the formation of a SiC network structure. The relationships between the content of SiC bonds, represented by the relative integrated intensity of the SiC IR band, and the film properties are determined. The number of SiC bonds is found to be a key parameter in the control of the examined film properties. The films deposited at TS = 350 °C appear to be very dense materials exhibiting small surface roughness and high refractive index. The results of the present study are compared with those reported for a-SiC:H films produced by RP-CVD from a triethylsilane precursor.

The a-SiC:H films were produced by remote hydrogen plasma chemical vapor deposition (RP-CVD) from bis(dimethylsilyl)ethane as a novel single-source precursor. The effect of substrate temperature (T-S) on the kinetics of RP-CVD, chemical composition, structure, surface morphology, and properties of resulting films (density, refractive index, photoluminescence, hardness, elasticity, and resistance to wear) is reported. The T-S dependence of film growth rate implies that RP-CVD is an adsorption controlled process. The increase of T-S from 30 degrees C to 400 degrees C causes the elimination of organic moieties from the film and the formation of Si-C network structure. The relationships between the relative integrated intensity of Si-C IR band and film properties were determined. The films deposited at T-S = 300 degrees C appear to be very hard materials exhibiting small surface roughness and low intensity of blue photoluminescence (PL). They seem to be suitable protective coatings for metals to increase their wear strength.

Communication: The effect of substrate temperature (TS) on the growth rate, chemical structure, surface morphology, density, refractive index and photoluminescence (PL) of a-SiC: H films is reported. The increase in TS from 30 degrees C to 400 degrees C causes the elimination of organic moieties from the film and the formation of Si-carbidic network structure. The films produced at high TS are morphologically homogeneous, dense, and hard materials of high refractive index and extremely low PL intensity.

Amorphous silicon carbonitride films were produced by remote hydrogen plasma CVD (RP-CVD) from Tris(dimethylamino)silane precursor. The effect of substrate temperature (T(s)) on the kinetics of RP-CVD, chemical composition, structure, surface morphology, and properties of resulting films is reported. The T(s) dependence of film growth rate imply that RP-CVD is an adsorption-controlled process. The increase of T(s) from 30 to 400 degrees C causes the elimination of organic moieties from the film and the formation of Si-C and Si-N network structure. The structure property relationships were determined. The films deposited at T(s)=300 degrees C appear to be dense materials exhibiting very small surface roughness, high hardness, and an extremely low friction coefficient. They seem to be suitable protective coatings for metal surfaces to increase their wear strength.

SiCN films were produced by remote microwave hydrogen plasma CVD (RP-CVD) from tris(dimethylamino) silane precursor using different substrate temperature in the range T(S) = 30-400 degrees C. The effect of T(S) on the rate of RP-CVD, chemical structure, surface morphology, density, and photoluminescence (PL) of resulting films is reported. The increase in T(S) causes the formation of silicon carbonitride network, marked densification and smoothening of film surface, as well as shift of PL peak position.

Core-shell particles of poly(styrene/alpha-tert-butoxy-omega-vinylbenzylpolyglycidol) P(S/PGL) were used as new building blocks for the assembly of a colloidal crystal. The added-value properties of these particles for photonic crystal architectures are their high hydrophilicity together with their thermoresponsivity. Indeed, the poglycidol-rich shell undergoes a phase transition above 45 degrees C, which leads to its collapse at the particle surface accompanied by a decrease in the particle diameter. The three-dimensional crystalline arrays display Bragg diffraction properties, as judged by angle-resolved reflectance spectroscopy. The thermoresponsivity of the colloidal assemblies was observed through modifications of their optical properties with respect to the temperature used during the assembly process. The wetting properties of the crystalline material were also shown to reversibly switch from hydrophilic to hydrophobic as a function of the assembly temperature, thus evidencing the reorganization of the surface polyglycidol chains during the polymer phase transition. This work shows conclusively that P(S/PGL) particles are promising alternatives to poly(N-isopropylacrylamide) and poly(ethylene glycol) particles for the elaboration of thermoresponsive colloidal crystals, with a phase transition situated in between those of these two polymers.

The surface morphology and physical (density), optical (refractive index), and mechanical (hardness, elasticity) properties of amorphous hydrogenated silicon carbide (a-SiC:H) films produced by remote microwave hydrogen plasma (RHP)CVD from a triethylsilane precursor are investigated. The effect of substrate temperature (varied in the range Ts = 30–400 °C) on the properties of a-SiC:H films is reported. In view of the atomic force microscopy (AFM) examination the films were found to be morphologically homogeneous materials exhibiting small surface roughness which varies with Ts in a narrow range of values (1.0–1.5 nm). The relationships between the film compositional parameter, expressed by the atomic concentration ratio Si/C, and structural parameter described by the relative integrated intensities of the absorption IR band from the SiC bonds (controlled by substrate temperature) are examined. On the basis of the results of these examinations, reasonable compositional and structural dependencies of film properties are determined. The properties of investigated a-SiC:H films are compared with those reported in the literature for films produced from various organosilicon precursors by different CVD techniques. Due to their good mechanical properties a-SiC:H films produced in a high substrate temperature regime (Ts = 300–400 °C) seem to be useful as protective coatings improving the surface mechanics of various engineering materials.