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This paper presents a detailed characterization of Ti surface geometries as produced by non-contact laser functionalization and its impact on the process of protein adsorption. The proposed surface modification is designed for the local treatment of implantable devices with original roughness. In this work, titanium plates were initially modified by the two most common mechano-chemical treatments, shot peening and acid etching. The material under study was next functionalized DLIL (Direct Laser Interference Lithography) in order to obtained two different surface patterns: grooves and islands. The modified surfaces were characterized in terms of their shape, roughness, wettability, surface energy and chemical composition. For this purpose, the following methods were used: scanning electron microscopy, optical profilometry, atomic force microscopy, contact angle measurements, and X-ray photoelectron spectroscopy. Protein adsorption tests were conducted to consider the potential of the proposed methodology in biomedical applications and to compare the influence of the two different surface patterns on the initial state of ossointegration. To this end, XPS and FTIR studies were conducted. The systematic analysis presented will be useful when selecting an appropriate surface geometry for the local surface functionalization of implantable devices.

Nanostructured artificial receptor materials with unprecedented hierarchical structure for determination of human serum albumin (HSA) are designed and fabricated. For that purpose a new hierarchical template is prepared. This template allowed for simultaneous structural control of the deposited molecularly imprinted polymer (MIP) film on three length scales. A colloidal crystal templating with optimized electrochemical polymerization of 2,3′-bithiophene enables deposition of an MIP film in the form of an inverse opal. Thickness of the deposited polymer film is precisely controlled with the number of current oscillations during potentiostatic deposition of the imprinted poly(2,3′-bithiophene) film. Prior immobilization of HSA on the colloidal crystal allows formation of molecularly imprinted cavities exclusively on the internal surface of the pores. Furthermore, all binding sites are located on the surface of the imprinted cavities at locations corresponding to positions of functional groups present on the surface of HSA molecules due to prior derivatization of HSA molecules with appropriate functional monomers. This synergistic strategy results in a material with superior recognition performance. Integration of the MIP film as a recognition unit with a sensitive extended-gate field-effect transistor (EG-FET) transducer leads to highly selective HSA determination in the femtomolar concentration range.

We demonstrate that a new, stable, artificial TATA (T — thymine, A — adenine) box is recognized by amino acids recognizing the natural TATA box. Here, the former mimicked, as a minimal motif, oligodeoxyribonucleotide interactions with amino acids of proteins involved in repairing of damaged dsDNA. By electropolymerization, we molecularly imprinted non-labeled 5′-TATAAA-3′ via Watson-Crick nucleobase pairing, thus synthesizing, in a one-step procedure, the hexakis[bis(2,2′-bithien-5-yl)] TTTATA and simultaneously hybridizing it with the 5′-TATAAA-3′ template. That is, a stable dsDNA analog having a controlled sequence of nucleobases was formed in the molecularly imprinted polymer (MIP). The 5′-TATAAA-3′ was by the X-ray photoelectron spectroscopy (XPS) depth profiling found to be homogeneously distributed both in the bulk of the MIP film and on its surface. The 5′-TATAAA-3′ concentration in the 2.8(±0.2)-nm relative surface area, ~140-nm thick MIP film was 2.1 mM. The MIP served as a matrix of an artificial TATA box with the TATAAA-promoter sequence. We comprehensively characterized this artificial DNA hybrid by the polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS) and X-ray photoelectron spectroscopy (XPS). Further, we examined interactions of DNA repairing TATA binding protein (TBP) amino acids with the artificial TATA box prepared. That is, molecules of l -phenylalanine aromatic amino acid were presumably engaged in stacking interactions with nucleobase steps of this artificial TATA box. The nitrogen-to‑phosphorus atomic % ratio on the surface of the MIP-(5′-TATAAA-3′) film increased by ~1.6 times after film immersing in the l -glutamic acid solution, as determined using the XPS depth profiling. Furthermore, l -lysine and l -serine preferentially interacted with the phosphate moiety of 5′-TATAAA-3′. We monitored amino acids interactions with the artificial TATA box using real-time piezoelectric microgravimetry at a quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) spectroscopy under flow injection analysis (FIA) conditions.

A 3-D molecularly imprinted polymer (MIP) film comprising a unit for recognition of 2,4,6-trinitrophenol (TNP) embedded with a fluorophore for signal transduction and quantification is newly fabricated and shown to be selective and sensitive to the target TNP analyte in solution. The limit of detection of this chemosensor reached a level of subnanogram per liter of TNP concentration. Moreover, this MIP film was fabricated by just one-step electropolymerization from a prepolymerization solution; therefore, the procedure is readily extendable for selective determination of other nitroaromatic explosives.

In this work analysis of thermal behavior of piezoresistive silicon Scanning Thermal Microscopy cantilever with integrated resistive metal tip is presented. In order to determine the temperature distribution of the tip in the case of present power supply micro-Raman spectroscopy was used. Two different excitation wavelengths, in particular from visible and ultraviolet spectral ranges, were applied. The application of different excitation wavelengths results in significantly different penetration depth of the light into the silicon. As a result the information from different depths of the material is detected. The results obtained from micro-Raman spectroscopy can be summarized in two points. First: the increase of the temperature is observed only in the vicinity of conducting tracks. This increase is of the order of 10K. Second: there is no large increase of the temperature in the thin layer of silicon substrate in the vicinity of silicon/silicon dioxide interface. Measured temperature distribution is compared with theoretical simulation calculated with Finite-Element Method and data obtained from thermal imaging. Calculated thermal effect can be summarized as follows: the temperature increases by 11K for conducting track, and by 9K for silicon in the vicinity of the track above the temperature of the environment. The increase of the temperature of the cantilever obtained from thermal imaging is equal to about 12K. Display Omitted Temperature distribution in new type of cantilever for SThM was investigated.All applied methods present the same results within their accuracies.Application of two excitation wavelengths allowed investigation of thermal effect for two different depths.Agreement between experimental techniques and theoretical calculations allowed to validate FEM models in microscale.

Presented work focuses the attention on two regions of MOS structure placed in the vicinity of the semiconductor/dielectric interface, in particular: on part of dielectric layer and thin layer of the substrate. In the presented work the application of absorption as a tool that can vary the absorption depth of excitation light into the semiconductor substrate is discussed. The changes of the absorption depth of visible light allows to obtain Raman signal from places in the substrate placed at different distances from the dielectric/semiconductor interface. The series of Raman spectra obtained from visible excitation in the case of varying absorption depth allowed to analyze the structure of the substrate as a function of distance from the interface. Deep ultraviolet Raman study regarding part of silicon dioxide layer placed directly at the interface is not discussed so far which makes the analysis of the structure of this part of dielectric layer possible. Comparison of reported in this work Raman data with structure of silicon/silicon dioxide interface obtained from other experimental techniques proves the applicability of proposed methodology.

This study proposes Direct Laser Interference Lithography as a highly suitable technique for functionalization titanium surfaces for biomedical applications. DLIL was employed to produce periodic patterns on titanium after two commonly used surface treatments of implantable devices (shot peening and acid etching). The biomedical potential of the proposed method was analyzed using immersion tests in a simulated body fluid solution and cell adhesion tests. After 48 h of immersion surface morphology, the chemical composition and phase structure of the apatite layers deposited on the modified titanium were analyzed. In order to analyze the kinetics of the apatite layer growth, X-Ray Photoelectron Spectroscopy measurements at different soaking times were performed. Cell adhesion tests were performed using human fetal osteoblastic cells (hFOB). The adhered cells were analyzed using confocal and scanning electron microscopies after 48 h of incubation. The formation of biomimetic apatite layers was accelerated on the titanium surface structures after DLIL modification. The periodic titanium patterns induced more uniform and direct cell growth. This effect is mainly connected with the surface properties of the DLIL-modified substrates. The formation mechanism of biomimetic apatite on the textured titanium samples, as well as the compounds created on the surface, are discussed.

This paper describes the effects of phosphorus implantation into n-type 4H-SiC substrate prior to standard dry oxidation process. Phosphorus incorporation has been reported to be one of the most efficient means of increasing SiC MOSFET field mobility however the physical basis of this phenomenon is still not clear. The aim of this research is to investigate the influence of phosphorus implantation on trap density profile close to conduction band of silicon carbide and to gain understanding of physical processes responsible for observed trap density improvement in phosphorus related oxidation technologies of silicon carbide.

By means of molecular imprinting of a conducting polymer, molecular cavities selective for oxytocin nonapeptide, an autism biomarker, were designed. Embedding of the oxytocin template, and then its extracting from the molecularly imprinted polymer (MIP) was confirmed by the XPS analysis. AFM imaging of the MIP film surface indicated changes in mechanical properties of the film after template extraction. The MIP synthetic receptor was deposited by potentiodynamic electropolymerization as a thin film on an Au film electrode in an electrochemical miniaturized microfluidic cell. The use of this cell allowed to shorten analysis time and to decrease the sample volume. The linear dynamic concentration range extended from 0.06 to 1mM with the limit of detection of 60µM (S/N = 3). Advantageously, sensitivity of the diagnostic microfluidic platform devised for oxytocin determination in both synthetic serum samples and in aqueous solutions was similar and, moreover, it was selective to common interferences, such as oxytocin analogs and potential metabolites.

The paper reports on the fabrication of electrical isolation for planar AlGaN/GaN high electron mobility transistor using Al double-implantation. The implantation was performed using Al+ ions with energies of 800 keV and 300 keV with doses of 1.5×1013 ion/cm2 and 1×1013 ion/cm2, respectively. Electrical measurements have shown that after implantation the sheet resistance was 1.8×1011 Ω/□ and increased to 1.17×1014 Ω/□ and 3.29×1012 Ω/□ after annealing at 400°C and 600°C respectively. Annealing at 800°C decreased the sheet resistance to 1.38×108 Ω/□. Characterization by XRD, Raman and photoluminescence spectroscopy give evidence that implantation damages the crystal lattice, yielding insulating properties. It has been demonstrated that the isolation is stable up to 600°C.

The 3C-SiC silicon carbide is a promising substrate material for MOS transistors. Parameters of MOS transistors are strongly dependent on the processing of the semiconductor-dielectric system. We study and compare the crucial features of the SiC(3C)-SiO2 systems with thermally grown and PECVD deposited SiO2 layers. For both types of systems, using the Al-SiO2-SiC(3C) capacitors as test structures, we determine and compare the following properties: The leakage currents and breakdown voltages of SiO2 layers, densities and distributions in energy of interface traps, band diagrams of the SiC(3C)-SiO2 systems, as well as structural properties and mechanical stresses in both types of SiO2 layers. Characterization of the above mentioned features is done using electrical, photoelectric and optical methods, including micro-Raman spectroscopy. The characterization results lead us to the conclusion, that PECVD deposition of SiO2 followed by wet oxygen annealing is more advantageous for MOSFET fabrication than the thermal growth of the SiO2 layer.

The structure of carbonic layer in three samples composed of 4H polytype of silicon carbide and the following sequence of layers: carbon/nickel/silicon/nickel/silicon was investigated with Raman spectroscopy. Different thermal treatment of the samples led to differences in the structure of carbonic layer. Raman measurements were performed with visible excitation focused on two interfaces: silicon carbide/carbon and carbon/silicide. The results showed differences in the structure across carbon film although its thickness corresponds to 8/10 graphene layers.

In this article, an influence of nitrogen implantation dosage on SiC MOS structure is analyzed using wide range of nitrogen implantation dose (between ~1013 – 1016). Authors analyzed electrical and material properties of investigated samples using C-V, I-V measurements, Raman spectroscopy, and XPS profiling. It has been shown that surface state trap density is directly connected to implantation damage and thus implantation conditions. Using research results a trap origin at given energy can be concluded.

Three samples of 4H polytype of silicon carbide (4H-SiC) covered with the following sequence of layers: carbon/nickel/silicon/nickel/silicon were investigated with micro-Raman spectroscopy. Different thermal treatments of each sample result in differences of carbon layer structure and migration of carbon atoms thorough silicide layer. Two ranges of Raman shift were investigated. The first one is placed between 1000 cm−1 and 2000 cm−1. The main carbon bands D and G are observed in this range. Analysis of the positions of these bands and their intensity ratio enables one to determine the graphitization degree of carbon layer. Additional information about the changes of the carbon layer structure was derived from analysis of 2D band placed around 2700 cm−1. Application of deep ultraviolet excitation delivered information about the structure of carbon layer formed on the free surface of silicides and the distribution of the carbon inside the silicide layer.

Silicon carbide (SiC) is a wide band gap semiconductor having good thermal conductivity and high break down voltage. Formation of SiO2layer in thermal oxidation process completes the set of properties of SiC as a promising material for fabrication of high power and high frequency electronic devices. This picture is perturbed by Near Interface Traps (NIT's) that decrease the surface mobility of charge carriers. The origin of NIT's is still the subject of discussion and there are several candidates for NIT's. One possibility is the formation of carbonic structures during the process of manufacturing of MOS-type structures. The aim of this work was to look for possible carbonic inclusions with Raman spectroscopy. The attention of authors was focused on non-destructive way of application of the experimental technique.

Silicon carbide (SiC) is a wide band gap semiconductor suitable for high power and frequency electronic devices. The most important features of the material making it promising in this application are good thermal conductivity, high breakdown voltage and formation of native SiO 2 layer on the surface of SiC substrate by thermal oxidation. However, the material has significant drawbacks. The most important one is low surface mobility. The surface mobility of the charge carriers is decreased by near interface states (NIT's — Near Interface Traps) — caused by defects formed in the vicinity of SiC/SiO 2 interface. There are several candidates for NIT's and one of them is the occurrence of carbonic structures. Raman spectroscopy provides information about investigated structure without destruction of the sample. The aim of this work was to look for carbonic inclusions in 4H and 3C polytypes of SiC. The attention was focused on this part of the range of the Raman Shift where the strongest bands of carbonic structures are expected.

The diheptyl-bipyridyl-diol, as a non-self-absorbing fluorescent compound characterized by a large separation between absorption and fluorescence bands, has been incorporated in polyvinyl-butyral film. Steady state luminescence and lifetime were measured. An increase of luminescence intensity by about 34% in the presence of silver nanoparticles was observed. No appreciable changes were found in the corresponding lifetimes. The system is proposed as a potential candidate for increasing the LSC efficiency.

We focus our attention to the laser-controlled association process of poly(N-vinylcarbazole) by “pure” photon pressure effect. A few wt % N,N-dimethylformamide solution of the polymer was irradiated with a focused 1064 nm laser beam of sub wattage power, and a resultant condensation (microparticle formation) at a focal point of the microscope was initially probed by backscattering of He−Ne laser and later observed by transmission image of the microscope. To understand in detail the behavior of the polymer induced by the photon force, the relation between laser power and particle diameter, as well as repeated irradiation effect, were investigated. The laser-controlled association was successfully demonstrated even for short polymer chains of about 20 mean degrees of polymerization. Fluorescence spectra and their rise and decay curves were measured microspectroscopically for a formed microparticle. The results are different from those of the polymer in solution, suggesting the association structure is chara...

Nickel-based contacts with additional interfacial layer of carbon, deposited on n-type 4H-SiC, were annealed at temperatures ranging from 600 to 1000°C and the evolution of the electrical and structural properties were analyzed by I-V measurements, SIMS, TEM, and Raman spectroscopy. Ohmic contact is formed after annealing at 800°C and minimal specific contact resistance of about 2.0×10-4 Ω cm2 has been achieved after annealing at 1000°C. The interfacial carbon is amorphous in as-deposited state and rapidly diffuses and dissolves in nickel forming graphitized carbon. This process activates interfacial reaction between Ni and SiC at lower temperature than usual and causes the formation of ohmic contact at relatively low temperature. However, our results show that the specific contact resistance as well as interface quality of contacts was not improved, if additional layer of carbon is placed between Ni and SiC.

Raman spectroscopy is a powerful experimental technique for structural investigation of silicon based electronic devices such as metal‐oxide‐semiconductor-type structures. It is widely used for characterization of mechanical stress distribution in silicon substrate. However, in the case of Raman measurements of oxide layer on silicon substrate visible excitation makes this technique almost useless. The reason for this difficulty is two-phonon scattering from silicon substrate which masks the signal from oxide layer. Application of deep-ultraviolet (deep-UV) excitation reduces the penetration depth of the radiation into silicon substrate about 30 times. As a result, the simultaneous measurement of one-phonon scattering from silicon substrate and the Raman spectrum of the oxide layer become possible. This work presents the study of thin silicon oxide film on silicon substrate with application of deep-UV Raman scattering. The spectra measured for thin film are compared with reference spectra obtained for bulk material.

Two kinds of samples were investigated with micro-Raman spectroscopy. MOS structures having poly-silicon gates with metallic contact were made of Al with addition of 1% Cu. The other type of the sample was Si wafer subjected to surface oxidation. The position of the sample was changed along z-axis in order to maximize the Raman signal coming from different layers of the structure. Two MOS structures were studied, both prepared in the same process, and after that only one was thermally-treated at temperature 400◦C. The spectra coming from different layers of the structure were analyzed numerically using Lorentzian profile. The authors want to point out that the measurements of the Raman signal performed through the metallic contact of the poly-silicon gate gave anomalously large signal coming from silicon structure. This effect was observed only for thermally threated sample. This suggest that in the case of thermally-treated structure the signal observed through the metallic contact was magnified by surface-enhanced Raman scattering phenomenon.

A new method for determination of the refractive index of any transparent solvent or glass was developed and tested for use at temperatures of 133–293 K in the ultraviolet and visible spectral ranges. The wavelength and temperature dependencies of the refractive indices of several solvents and of fused silica are reported. The data obtained for tetrachloromethane and fused silica are compared with those available in the literature. The advantages and limitations of the method are discussed, based on the accuracy of the data presented. Knowing the values of refractive indices of organic solvents should be useful in luminescence spectroscopy.

Microassociation of poly(N-vinylcarbazole) by a focused near-infrared laser beam (cw-YAG, 1064 nm) was first demonstrated in organic solvents. Investigations were made in cyclohexanone and N,N-dime...

The signal coming from SiO2 layer of MOS structure have large noise-to-signal ratio. This has two reasons — first: the dielectric layers have small Raman eciency, second: the thickness of the dielectric layers are of the order of 10 nm, so the volume of the material irradiated with laser light is small. At the other side spectroscopic and optical data carry the information about important properties of the structure like mechanical stress. Distribution of mechanical stress introduce an important contribution to the electric properties of the electronic systems based on the MOS structures. Therefore, it is important to “distillate” the optical data from the noise. In this contribution the authors discuss some methods of denoising of the Raman signal. The discussed methods compare treatments like wavelet analysis or convolution. The work is illustrated with some examples of the extraction of the data coming from thin layers. The examples of application of the optical data in the description of the properties of the studied structures are presented.