Marijan Maček

Infrared Optical Constants and Dielectric Response Functions of Silicon Nitride and Oxynitride Films

The complex refractive indices of thick plasma-enhanced chemical vapour deposited silicon nitride and oxynitride films were determined within the infrared spectral region (4000-400 cm -1 , i.e. 2.5-25 μm) and used further to obtain their complex dielectric response functions. The imaginary part, i.e. the so-called energy-loss-function was analysed to get accurate phonon data of the amorphous layer. This way, TO-phonon frequencies, half-widths, and intensities of characteristic infrared absorptions were determined for each film. The dependence of the obtained data upon the variation of chemical/physical structure of the amorphous lattice was discussed.

Comparison of structural and chemical properties of Cr-based hard coatings

Abstract A series of chromium nitride, carbide and carbonitride coatings were prepared by ion plating using nitrogen and acetylene as reactive gases. The depositions were made at different partial pressures of the reactive gases while maintaining other parameters constant. The crystal structure and microstructure were studied by TEM. The CrN and Cr 2 N phases were detected in the chromium nitride coatings. In the carbide coatings, orthorhombic Cr 7 C 3 and the metastable cubic CrC phase were confirmed. For oxidation studies, the samples were annealed at 750 °C. Afterwards, the depth profile was measured by glow discharge optical emission spectrometry (GDOES). A complex diffusion was observed involving outdiffusion of nitrogen and segregation of carbon at the substrate-coating interface.

Properties of Cr(C,N) hard coatings deposited in ArC2H2N2 plasma

Abstract Several chromium carbonitride (Cr(C,N)) coatings were prepared with different C:N ratios by varying the N 2 and C 2 H 2 flow. Chromium nitride (CrN) and chromium carbide (CrC) coatings were also prepared for comparison. The coatings were deposited in two different ion-plating systems: by reactive evaporation in BAI730M (Balzers) apparatus at high temperature (450 °C) and by reactive sputtering in plasma-beam Sputron (Balzers) apparatus at low temperature (200 °C). Among mechanical properties microhardness, adhesion (measured by scratch test) and surface roughness were evaluated. Oxidation of the coatings was carried out by heating the samples at temperatures of 750–900 °C in an oxygen atmosphere. Crystal structure and microstructure were studied by XRD, TEM and SEM. Chemical State of the elements was observed by XPS. The concentration and depth profiles of the samples oxidized at various temperatures were measured by AES, EDX and GDOES.

Energy resolved ion mass spectroscopy of the plasma during reactive magnetron sputtering

Abstract The energy distribution and composition of the ion flux on a substrate during reactive magnetron sputtering of TiN and TiWN films were studied by the energy resolved mass spectroscopy. The entrance flange of the probe Hiden EQP500 was positioned in a distance of 50 mm from the Ti or WTi (70:30 at.%) target 100 mm in diameter. The sputtering was carried out in a mixture of argon and nitrogen of various compositions at pressures from 0.05 to 10 Pa and discharge currents from 0.5 to 7 A. The energy spectra of ions at low pressures were characterized by extended high-energy tails. The high energy of sputtered (metal) atoms follows from their distribution at the cathode after being sputtered. The high-energy gas ions (Ar + , N 2 + , N + ) stem from two sources. One is the transfer of energy in the collisions with the sputtered metal atoms. The other is the reflection of the energetic ions from heavy elements in the target. A strong reduction of the ion energy at the substrate was found when the pressure was increased from 0.5 to 10 Pa. As a consequence of a loss of energy in many collisions the high-energy portion of the ion energy spectra diminished and the energy spectra of various kinds of ions became similar. Nevertheless, the reflected ions were still apparent, albeit at lower intensity. The TRIM Monte-Carlo simulation showed that the flux of the fast reflected ions and flux of sputtered atoms are of the same order of magnitude, indicating thus the important role of the former species in forming the film properties at low pressures. The analysis of the composition of the ion flux during sputtering in a mixture of nitrogen and argon revealed that the ratio of ion fluxes TiN + /Ti + reached maximum of approximately 0.13, while WN + /W + was up to 0.3.

Carbon-containing Ti–C:H and Cr–C:H PVD hard coatings

Abstract Ti–C:H and Cr–C:H coatings were prepared by reactive sputtering in a Balzers Sputron deposition system at a substrate temperature of approximately 150°C. Acetylene was used as reactive gas. Coatings were deposited onto polished tool steel and silicon substrates. Transmission electron microscopy, Auger electron spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, scratch test and microindentation were used to characterize the properties of the coatings.

Sensitivity Comparison of Vapor Trace Detection of Explosives Based on Chemo-Mechanical Sensing with Optical Detection and Capacitive Sensing with Electronic Detection

The article offers a comparison of the sensitivities for vapour trace detection of Trinitrotoluene (TNT) explosives of two different sensor systems: a chemo-mechanical sensor based on chemically modified Atomic Force Microscope (AFM) cantilevers based on Micro Electro Mechanical System (MEMS) technology with optical detection (CMO), and a miniature system based on capacitive detection of chemically functionalized planar capacitors with interdigitated electrodes with a comb-like structure with electronic detection (CE). In both cases (either CMO or CE), the sensor surfaces are chemically functionalized with a layer of APhS (trimethoxyphenylsilane) molecules, which give the strongest sensor response for TNT. The construction and calibration of a vapour generator is also presented. The measurements of the sensor response to TNT are performed under equal conditions for both systems, and the results show that CE system with ultrasensitive electronics is far superior to optical detection using MEMS. Using CMO system, we can detect 300 molecules of TNT in 10+12 molecules of N2 carrier gas, whereas the CE system can detect three molecules of TNT in 10+12 molecules of carrier N2.

Surface-Functionalized COMB Capacitive Sensors and CMOS Electronics for Vapor Trace Detection of Explosives

In this paper, we present a miniature detection system, which is able to detect and selectively recognize different vapor traces of explosives. It is based on surface-functionalized array of COMB capacitive sensors and extremely low noise integrated electronics. The measurement system is sensitive and selective, consumes minimum amount of energy, is very small and cheap to produce in large quantities, and is insensitive to environmental influences. Owing to extremely low noise electronics and selective modification of COMB capacitor surfaces, it is possible to detect less than 3.5 ppt of TNT in the atmosphere (three TNT molecules in 10+12 molecules of air and 10 times better for RDX) at 25°C in one second using very small volume (few mm3). The measurement system needs only approximately 20 mA current at 5 V supply voltage.

A study of plasma parameters in a BAI 730 M triode ion plating system by means of a Langmuir probe and plasma mass and energy spectroscopy

Abstract The plasma in a physical vapor deposition (PVD) system used for the deposition of hard coatings (TiN, CrN) was studied by means of a Langmuir probe and energy resolved spectroscopy (Balzers plasma process monitor PPM 421). I – V measurements gave the plasma ( U pl ) and floating ( U fl ) potentials, as well as the electron temperature T e and plasma density n i . U pl deduced from I – V measurements agreed well with the peak of the positive ion energy distribution, as well as with the highest positive potential for the given operational mode. Energy spectra measured in deposition of TiN show a high degree of ionization of Ti, with Ti 2+ as the prevalent ion. T e calculated from the Maxwellian distribution for the standard deposition of TiN is rather high ( T e =6–8 eV). We believe that the oscillations of the plasma potential with the measured amplitude up to 15 V are most probably the reason. The electron energy distribution F ( E ) is better described by the Druyvesteyn distribution one than by a Maxwellian one.

Energy-resolved mass spectroscopy of Ar–C2H2–N2 plasma, performed during ion plating of TiC and TiN hard coatings

Abstract Energy-resolved mass spectroscopy studies during discharge in Ar+N 2 and Ar+C 2 H 2 gas mixtures in a triode ion-plating apparatus (Balzers BAI 730) revealed a high degree of acetylene (C 2 H 2 ) decomposition under typical conditions suitable for titanium evaporation. In the case of the Ar+C 2 H 2 gas mixture, the most abundant neutral species besides argon is hydrogen, and not acetylene as would be expected. On the other hand, the 12 C + ion is the most abundant carbon-containing species. The ratio between C + , CH 3 + and C 2 H 2 + ions and titanium ions (Ti + , T 2+ ) decreases with increasing arc current. By careful adjustment of the discharge parameters, either a plasma rich in C x H y radicals with a low metal evaporation rate or plasma with a high evaporation rate but with almost completely decomposed acetylene, i.e. with C + and H n =1–3 + only, can be obtained.

Effect of reactive gas pressure on the plasma parameters during triode ion plating of Cr−C films

AbstractMechanical properties and the average chemical composition of Cr−C hard coatings deposited by means of triode ion plating strongly depends on the partial pressure of the reactive gas (C2H2) during the deposition. The partial pressure of the acetylene has to be higher ( % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqr1ngB% PrgifHhDYfgasaacH8srps0lbbf9q8WrFfeuY-Hhbbf9v8qqaqFr0x% c9pk0xbba9q8WqFfea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qqQ8fr% Fve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaatCvAUf% KttLearyqr1ngBPrgaiuGacqWFWbaCdaWgaaWcbaacfaGae43qam0a% aSbaaWqaaiab+jdaYaqabaacbaWccaqFibWaaSbaaWqaaiab+jdaYa% qabaaaleqaaOGaeyypa0Jae4xmaeJae4Nla4Iae4xnauJae4hiaase% fWuDJLgzHbYqV52CVXwzaGGbaiaa8DnacqGFGaaicqGFXaqmcqGFWa% amdaahaaWcbeqaaGGaaiab7jHiTiab+ndaZaaakiaa9bcacqGFTbqB% cqGFIbGycqGFHbqycqGFYbGCaaa!5816!