Abstract:This work focuses on silicon oxycarbide thin film preparation and characterization. The Taguchi method of experimental design was used to optimize the process of film deposition. The prepared ceramic thin films with a thickness of ca. 500 nm were characterized concerning their morphology, composition, and electrical properties. The molecular structure of the preceramic polymers used for the preparation of the ceramic thin films as well as the thermomechanical properties of the resulting SiOC significantly infl… Show more
“…In our previous works, we gained insight into the deposition method of polysiloxane precursor on a 100 mm diameter silicon substrate, obtaining a 500 μm thick, homogeneous, and crack-free piezoresistive silicon oxycarbide thin film . Morphological investigation of the SiOC thin film revealed compositional segregations, as shown in Figure .…”
Section: Resultsmentioning
confidence: 99%
“…Morphological investigation of the SiOC thin film revealed compositional segregations, as shown in Figure . Oxygen-depleted segregations, consisting of carbon and silicon carbide domains, are homogeneously distributed within a C/SiOC matrix (see Figure A). The segregation of the C/SiC regions does not occur with a significant change in the thickness or roughness of the film, as shown in Figure B, in which the surface of the sample is tilted by 52°.…”
The nonlinear response of strain gauges at high temperatures has restricted their applications despite their highprecision and real-time measurement capability. This work addresses this limitation by utilizing the easy preparative access and versatility of silicon oxycarbide-based (SiOC) thin films as strain gauges offering outstanding high-temperature robustness and giant piezoresistive response. The sensitivity of the strain gauge is assessed with continuous cyclic loads, tensile and compressive, resulting in gauge factors of ca. 2000−5000. The linearity of the response is preserved up to 700 °C with a shift in the electrical response occurring at temperatures beyond 500 °C, switching the SiOC film from semiconducting to conducting behavior. This change causes a drop in the gauge factor of the SiOC-based thin films; nevertheless, it is still significantly higher than that of metallic and Si-based commercial strain gauges. Notably, the studied thin films can regulate the effect of temperature enabling them to be a highly sensitive device with good reversibility and replicability in high-temperature environments. Furthermore, the electrical shift at 460 °C broadens the application of the SiOC film as a currentlimiting device and temperature sensor.
“…In our previous works, we gained insight into the deposition method of polysiloxane precursor on a 100 mm diameter silicon substrate, obtaining a 500 μm thick, homogeneous, and crack-free piezoresistive silicon oxycarbide thin film . Morphological investigation of the SiOC thin film revealed compositional segregations, as shown in Figure .…”
Section: Resultsmentioning
confidence: 99%
“…Morphological investigation of the SiOC thin film revealed compositional segregations, as shown in Figure . Oxygen-depleted segregations, consisting of carbon and silicon carbide domains, are homogeneously distributed within a C/SiOC matrix (see Figure A). The segregation of the C/SiC regions does not occur with a significant change in the thickness or roughness of the film, as shown in Figure B, in which the surface of the sample is tilted by 52°.…”
The nonlinear response of strain gauges at high temperatures has restricted their applications despite their highprecision and real-time measurement capability. This work addresses this limitation by utilizing the easy preparative access and versatility of silicon oxycarbide-based (SiOC) thin films as strain gauges offering outstanding high-temperature robustness and giant piezoresistive response. The sensitivity of the strain gauge is assessed with continuous cyclic loads, tensile and compressive, resulting in gauge factors of ca. 2000−5000. The linearity of the response is preserved up to 700 °C with a shift in the electrical response occurring at temperatures beyond 500 °C, switching the SiOC film from semiconducting to conducting behavior. This change causes a drop in the gauge factor of the SiOC-based thin films; nevertheless, it is still significantly higher than that of metallic and Si-based commercial strain gauges. Notably, the studied thin films can regulate the effect of temperature enabling them to be a highly sensitive device with good reversibility and replicability in high-temperature environments. Furthermore, the electrical shift at 460 °C broadens the application of the SiOC film as a currentlimiting device and temperature sensor.
“…The film thickness was determined using a profilometer (Dektak XT Advanced System, Brucker, Karlsruhe, Germany) and measured in three different positions for each sample. The full details of the optimization process including the statistical approach are reported in detail in Reference 24. A favorable response was obtained using the setting of an initial spin speed of 4000 rpm for 30 s, then accelerated to a second spin speed of 8000 rpm for 30 s with an acceleration of 500 rpm/s.…”
Section: Methodsmentioning
confidence: 99%
“…22,23 A significant amount of literature is available on the synthesis approach and characterization of SiOC, although the majority is dedicated to powder and monolithic samples. In our latest work on SiOC thin film deposited on a silicon substrate, the evolution of the SiC and free carbon phases were documented at a temperature of 1400 • C. 24,25 A micro-scale segregation of phases was observed on the surface of the film; the segregations were found to consist of sp 2-h ybridized carbon and nanocrystalline β-SiC dispersed within an amorphous silicon oxycarbide matrix. The Si-O-C system is known to follow two processes when exposed to temperatures well beyond 1000 • C: The first process involves the partitioning of the glassy SiO 4−x C x network and the formation of amorphous silica and SiC nanodomains, latter may crystallize; the second process represents the carbothermal reaction between the phaseseparated silica and the excess carbon, complemented by the growth of crystalline SiC and release of gaseous CO. 9 These processes were extensively studied and are relatively well understood for monolithic SiOC.…”
Section: Introductionmentioning
confidence: 99%
“…A significant amount of literature is available on the synthesis approach and characterization of SiOC, although the majority is dedicated to powder and monolithic samples. In our latest work on SiOC thin film deposited on a silicon substrate, the evolution of the SiC and free carbon phases were documented at a temperature of 1400°C 24,25 . A micro‐scale segregation of phases was observed on the surface of the film; the segregations were found to consist of sp 2 ‐hybridized carbon and nanocrystalline β‐SiC dispersed within an amorphous silicon oxycarbide matrix.…”
Silicon oxycarbide film deposited on a silicon substrate has shown superior electrical conductivity relative to its monolithic counterpart. In this work, the evolution of different microstructures detected on the SiOC film reveals its hierarchical microstructure. The existence of sp2‐hybridized carbon domains has been unambiguously confirmed by means of Raman spectroscopy and transmission electron microscopy corroborated with electron energy loss spectroscopy. The diffusion coefficient of carbon in silica and its dependence on temperature were studied by assessing energy‐dispersive X‐ray spectroscopy profiles taken from the cross‐sections of samples annealed at temperatures in the range from 1100°C to 1400°C. The activation energy for diffusion of carbon in silica was determined to be approximately 3.05 eV, which is significantly lower than the values related to the self‐diffusion of silicon and oxygen. The microstructural evolution of precursor to SiCnO4‐n and SiC serves as migration path of sp2‐hybridized carbon to the SiOx layer. With increasing temperature, the formation of microscale carbon‐rich segregation is promoted while the SiOC film becomes thinner.
In the present work, transition metal‐containing preceramic silicon polymers were synthesized via chemical modification of a commercially available organopolysilazane with Hf and Ta amido complexes as well as with borane dimethyl sulfide complex. The incorporation of transition metals into the polymer structure, their influence on ceramization and processability were thoroughly investigated. Moreover, the prepared preceramics were coated onto silicon wafers via spin coating and converted into crack‐free, amorphous SiHfTa(B)CN based ceramic coatings with excellent adhesion to the substrate. The composition of the ceramic coatings was investigated via XPS and their high‐temperature behavior was studied via oxidation tests performed at 1100 °C. Moreover, a thermal cycling procedure to temperatures above 1250 °C with rapid heating and cooling rates (i.e., in the range of 100‐120 K/s) was applied to the ceramic coating, which showed no damage even after ten thermal cycles, indicating their outstanding performance and their potential for use as environmental barrier coatings at high temperatures.TOC: In the present study, single source precursors were obtained through the modification of a commercially available organopolysilazane with Hf, Ta and B. The preceramic polymers show good processability and yield dense, crack‐free and homogeneous ceramic coatings with excellent thermal cycling stability.This article is protected by copyright. All rights reserved.
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