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This paper is dedicated to preparation and analysis of metal insulator semiconductor (MIS) photoanode with a metal organic chemical vapor deposited RuO2 layer and TiO2 protection layer for photoelectrochemical water splitting. It is shown that utilization of TiO2 layers of 2, 4, and 6 nm thickness preserve the catalytic activity of underlying RuO2. The origin of increased overpotential and decreased photovoltage of the photoanode upon the increase of TiO2 layer thickness is discussed in the paper. Results revealed that utilization of TiO2 layer in the MIS concept is suitable for photoelectrochemical water oxidation applications.

We present results on very thin NiO films which are able to detect 3 ppm of acetone, toluene and n-butyl acetate in synthetic air and to operate at 300°C. NiO films with 25 and 50 nm thicknesses were prepared by dc reactive magnetron sputtering on alumina substrates previously coated by Pt layers as heater and as interdigitated electrodes. Annealed NiO films are indexed to the (fcc) crystalline structure of NiO and their calculated grain sizes are in the range from 22 to 27 nm. Surface morphology of the examined samples was influenced by a rough and compact granular structure of alumina substrate. Nanoporous NiO film is formed by an agglomeration of small grains with different shapes while they are created on every alumina grain.

A novel approach based on the application of light irradiation during the electrodeposition is proposed to prepare Cu2O structures for photoelectrochemical water splitting. Potentiostatic deposition of Cu2O layers under irradiation and in the dark was carried out from lactate-stabilized copper sulfate on Ag coated glass substrates. The higher growth speed for light deposited samples is related to the contribution of photogenerated carriers to the reduction of electrolyte and electrodeposition of Cu2O. The light deposited samples exhibited higher photoresponse of 3.37 mA/cm2 compared to 2.5 mA/cm2 measured for dark deposited sample. Better carrier collection due to larger grain size and lower impurity incorporation are suggested as possible sources of the higher photoresponse for light deposited sample. The presented study demonstrates the light electrodeposition as an attractive way for preparation of highly photoactive Cu2O structures for water splitting applications.

Our activities were focused on the preparation of WS2 films on sapphire substrates by sulfurization of different thick sputtered W films. The influence of very thin W films in the range from 4 nm to 12 nm on the structural, morphological and optical properties of WS2 was investigated. XRD measurements revealed a polycrystalline nature with hexagonal symmetry and randomly connected nanocrystals with grain size about 6 nm for all WS2 films. Using Raman spectroscopy with a 532 nm laser excitation, the presence of characteristic E12g and A1g vibration modes was recorded and the multilayered nature of the prepared WS2 films was confirmed. FESEM observations revealed randomly oriented lamellar and flake-shaped microstructures with the basal plane of the WS2 crystallites. Thinner WS2 films (20 and 24 nm) showed highly dense horizontally aligned flakes. On the other hand, thicker WS2 films (33 and 42 nm) indicated a granular surface and the WS2 crystallites grew perpendicularly to the substrate surface. All examined WS2 films were transparent from 30 to 78% in the spectral range of 500 to 900 nm and showed a direct bandgap of 2.3 eV.

Metal-oxide nanostructures with precisely controlled geometries can play an important role in the technological improvement of sensors for gas detection. In this article we deal with the preparation of sensoric structures of sputtered TiO2 film the aim of which is for detection of environmental gases such as COx, NOx or NH3 and the like. Thin polycrystalline TiO2 deposited on a resistive layer of SiO2 was patterned by Electron-Beam Lithography (EBL) and subsequently Reactive Ion Etching (RIE) etched to obtain controlled geometrical extension of its active area. The increase and enhancement of the TiO2 active area was also controlled by its annealing and Ion Coupled Plasma (ICP RIE) etching through a Hydrogen Silsesquioxane (HSQ) resist mask or eventually an aluminum mask.

This paper is dedicated to the characterization of MoS 2 supercapacitor structures by means of electrochemical methods. The pseudocapacitive behaviour of MoS 2 structure is suggested as a dominant charge mechanism. The strong impact of the scan rate on the specific capacity is observed indicating a high impact of supercapacitor porosity on the capacity. Supercapacitor structures were subjected to the long-term electrolyte treatment. An increase of the specific capacity upon the electrolyte treatment is analysed by evaluation of morphological factor.

In this paper, experimental results are presented on the deposition of colloidal gold nanoparticles on the surfaces of TiO2 prepared on silicon/silicon dioxide. Important procedures, such as titanium dioxide surface hydrophilization as well as functionalization by an organosilane coupling agent (3-aminopropyl) trimethoxysilane and (3-mercaptopropyl) trimethoxysilane were investigated in order to obtain a metal oxide surface with the most convenient properties for immobilization of gold nanoparticles having a dense and uniform distribution. TiO2 nanotips prepared by reactive ion etching of oxide surface covered with self-mask gold nanoparticles are demonstrated.

Patterning of metal oxide nanostructures with different shapes and well-defined size may play an important role in the improvement of MEMS systems, sensors and optical devices. We investigated the effects of HSQ e-beam resist processing on the fabrication of sputtered TiO2 nanostructures. They were patterned using direct write e-beam lithography combined with ICP-RIE etching in CF4/Ar plasma. Experimental results confirmed that the HSQ resist with a thickness of about 600 nm is suitable as a masking material for optimal etching process and allows patterning of the dots array in TiO2 sputtered films with a thickness up 150 nm. TiO2 arrays with a minimal dots diameter of 180 nm and spacing of 1000 nm were successfully developed.

We present structural, optical and electrical investigations of layered WS2 films prepared on tungsten. A two-step technique has been used to synthesize layered WS2 films using sulfurization of W films sputtered with thinner (1 and 2 nm) and thicker (14 and 28 nm) thicknesses at 800 °C. XRD analysis revealed that the examined films are polycrystalline with texture and have a 2H-WS2 hexagonal microstructure. Using Raman spectroscopy with the 532 nm laser excitation, the presence of E12g and A1g vibration modes was observed and the layered nature of WS2 was confirmed. FE SEM observations showed two different surface morphologies. The samples grown on thinner W films were not compact over the surface and agglomeration of nanosize grains in combination of triangles and flakes was visible. In another group the surface was lamellar and contained plenty of nanorods embedded vertically and/or inclined at different angles to the surface. Layered WS2 films exhibited a direct band gap in the range of 2.1–2.5 eV and they were n-type semiconductors with the sheet resistance in the order of several MΩ at room temperature.

We present the basic growth knowledge and the building mechanism on layered WS2 thin films prepared on sapphire substrates by sulfurization at 800 °C of sputtered precursor W with 14 and 28 nm thicknesses. The recorded XRD patterns from both types of samples indicate that a 2H-WS2 hexagonal microstructure with the grain size of about 9 nm was created. However, the intensities of the (100) and (110) peaks were very weak in comparison with that of the (002) peak. From SEM observations it was identified that the WS2 layer is not compact in its depth and many flakes in combination with nanorods and nanowires are visible and in addition they are embedded into the basal material in both investigated samples. We assume that the quantification of nanorods parameters together with detailed XRD evaluation are effective methods to get more information on non-closed layered WS2 films.

This study is dedicated to fabrication and characterisation of a Cu20 gas sensor prepared by potentiostatic electrodeposition on interdigitated electrodes. A new simple and low cost approach based on the overgrowth of IDE fingers by Cu20 layer is used for fabrication of gas sensing structures. Tuning of the deposition charge is shown as a key factor to obtain optimal fingers overgrowth and Cu 2 0 crystals interconnection and hence sensor sensitivity. Comparison of sensors prepared in electrolyte with KOH and LiOR buffers revealed superior sensitivity for the later type. The developed sensor achieved a sensitivity of 3.7 to 1000 ppm of R 2 gas measured at 200°C.

This paper describes fabrication and characterisation of Ruo2 based metal-insulator-semiconductor (MIS) structure for photoelectrochemical water splitting. The expected high catalytic activity, transparency, stability and conductivity of Ruo2 make this material highly appealing for preparation of a photoanode with high performance. Optical, electrical and photoelectrochemical properties of Ruo2based MIS structures are compared with MIS structures with a Ni catalytic layer. The lower overpotential $V_{\text{op}}=0.12\mathrm{V}$ of Ruo2structure compared to $V_{\text{op}}=0.3\mathrm{V}$ obtained for Ni structure as well as higher saturation photocurrent indicates promising application of the developed Ruo2 structures for solar water splitting.

A novel wafer level and fully CMOS-compatible spray pyrolysis manufacturing process for SnO 2 -based gas sensors was developed. SnO 2 -sensor families making use of different additional nano materials like Au, Pt and Pd and combinations of them applied to the sensor surface were manufactured. The sensors were exposed to specific gases like CO, CO 2 and volatile organic compounds (VOCs) for sensor array characterization according to an application for climate control in rooms as defined in the IOSENSE project. In addition, sputtered NiO sensors exhibited very good long time stability and they reached the best results at 200°C when the relative sensitivity was in the order of 104.

Potentiostatic electrodeposition conducted at various deposition voltages from lactate-stabilized copper sulfate electrolyte was used for preparation of Cu2O layers for Photoelectrochemical (PEC) production of hydrogen. A novel approach based on an application of light during the electrodeposition is utilized to suppress the potential drop in the Cu2O layer during the potentiostatic deposition. Structures prepared under dark and light on an Ag substrate are analyzed by X-Ray Diffraction analysis (XRD), Scanning Electron Microscopy (SEM) and Linear Sweep Voltammetry (LSV). It was shown that the application of light increases the deposition rate due to the contribution of the photogenerated carriers. The deposition voltage affects the photoresponse of light deposited structures but causes only a negligible change in dark deposited structures. The light deposited samples exhibited a higher photoresponse for all deposition voltages. The presented study suggests the light potentiostatic electrodeposition as an attractive approach for the preparation of Cu2O structures for cheap and efficient photoelectrochemical water splitting applications.

Titanium oxide thin films were deposited at room temperature by reactive magnetron sputtering in a mixture of oxygen and argon on oxidized silicon substrates. The optimal etching characteristics of TiO2 films by an inductively coupled plasma system were investigated. The maximum etch rate of TiO2 was 104 nm/min at fixed 200 W of ICP power and the highest investigated value of RF chuck power of 150 W. Patterning of TiO2 tip arrays by electron beam lithography and dry etching was conducted. Experimental results showed that the exposure dose optimization was a significant parameter for controlling the tip size and its shape. Pyramidal TiO2 tip arrays were successfully fabricated by dry etching in CF4/Ar plasma through a Au nanoparticle mask. The TiO2 tip arrays can be expected to have an important application in gas microsensors.

a b s t r a c t Double layer films based on TiO2 and NiOx for gas detection were studied. Two layouts with opposite position of functional films were deposited via DC magnetron sputtering method and annealed at 600 ◦ C. The compositional, structural, morphological, electrical and gas sensing parameters were investigated. The depth profiles and the chemical state of the thin films elements were explored by X-ray photoelectron spectroscopy (XPS). Differences between the surface and subsurface NiOx were confirmed. In this way the formation of surface oxides and subsurface metallic Ni were observed. The structural changes and polycrystalline character were noticed by X-ray diffraction (XRD). The atomic force microscopy (AFM) revealed nanocrystalline character of the examined surfaces (both layouts). Different position of TiO2 and NiOx functional films brought difference in the type of response to reducing gas. Moreover, inversion of response type due to different H2 concentrations was confirmed.

Voltammetric sensors based on bismuth film electrodes are an attractive alternative to other sensors for application in electroanalysis of heavy metals. Bismuth film electrodes can be formed by a similar method on the same substrates as mercury. These systems were used most frequently for simultaneous determination of heavy metals such as Pb, Cd and Zn by anodic stripping voltammetry. Our voltammetric sensor was fabricated on an alumina substrate. A photoresist film prepared by pyrolysis of positive photoresist S-1813 SP15 on the alumina substrate was used as an electrode support for bismuth film deposition. The influence of the Nafion membrane on the measurement sensitivity of the sensor and mechanical stability of the bismuth film were investigated. The sensor was successfully applied for determination of Pb, Cd and Zn in an aqueous solution in the concentration range of 0.2 to 10 µg L−1 by square wave anodic stripping voltammetry on an in-situ formed bismuth film electrode with Nafion-coating. Parameters of the sensor such as sensitivity, linearity, detection limit, repeatability and life-time were evaluated. In the best case, the detection limits were estimated as 0.07, 0.11 and 0.63 µg L−1 for Pb, Cd and Zn, respectively. Finally, the applicability of the sensor was tested in analysis of Pb, Cd and Zn in real samples of tap and river water using the method of standard additions.

Indium tin oxide (ITO) thin films for application in thin-film silicon solar cells with superior electrical and optical properties (resistivity ranging from 1.4 to 8.4 × 10 −4 Ω cm; transparency of >80%) have been investigated. ITO layers were deposited by radio-frequency (RF) magnetron sputtering process at different argon gas pressures and substrate temperatures ranging from room temperature to 280 °C. The main goal was to identify the relationship between structural and electrical properties. Generally, ITO layers were rather smooth with granular topography; electro-optically superior layers exhibited substantially different surface morphology of large, well-organized domain formations. Hall mobility of remarkably high value of 49 cm 2 /V s (resistivity of 2.6 × 10 −4 Ω cm) was achieved for the ITO layers, which were deposited at surprisingly low temperature of 125 °C. ITO process has been successfully applied, even at room temperature, to fabricate front contacts for microcrystalline silicon solar cells, exhibiting excellent performance on both rigid and flexible substrates.

The effect of NiO additives and post-deposition treatment by rapid thermal annealing on the properties of TiO2 thin films has been studied. The structural, compositional and H2 sensing parameters have been investigated by X-ray diffraction (XRD), glow discharge optical emission spectrometry (GDOES), scanning electron microscopy (SEM) and by electrical measurements. In the range of annealing temperatures from 500 °C to 700 °C crystallization started and the structure changed from amorphous to polycrystalline. The NiO modified sensing films exhibit enhanced and improved sensing behavior to hydrogen at relatively low operating temperatures. The inversion of the conductivity type of response due to different H2 concentrations has been observed. The critical H2 concentration causing break of the p-type response to n-type response was identified. The temperature dependence of this critical concentration as a function of operating temperature was studied. Moreover, change of response type due to different annealing temperatures was achieved.

Nickel oxide, NiO is a perspective metal oxide with the ability to detect hazardous and flammable gasses. The detection process is based on the change of the conductivity of the NiO layer upon the presence of the gas. To tune the sensing properties of NiO sensor, it is necessary to obtain more comprehensive understanding of current transport processes in the structure. In this paper, we present an impedance characterization of NiO based sensor, which allowed to distinguish three conduction mechanism responsible for the current flow in the structure.

The nickel oxide (NiO) thin films were deposited by dc reactive magnetron sputtering from Ni target. Investigation of surface NiO was carried out by AFM measurements. NiO films are smooth and have an average roughness of 1.04 nm and 0.69 nm for 100 nm and 50 nm thickness of NiO film, respectively. Measured NiO films demonstrate to detect low concentration H2 at temperature 250°C. It was observed the improvement detection characteristics for thinner 50 nm NiO films in all investigated concentration H 2 and operational temperature.

We present a Pt film temperature element of the size of 1.5×1.5 mm2 with the meander width of 20 μm. It was investigated the effect of Pt film thickness prepared on alumina ceramics and the post-deposition annealing process on structural and electrical properties. As-deposited Pt films are polycrystalline with strongly preferred orientation on the (111) plane and the grains size is about 20 nm. The peak strength of (111) increased after annealing for all investigated samples and also the grain sizes increased up to 67 nm. Annealed Pt films exhibit a lower resistivity in comparison with the as-deposited films.

We present results on single and mixed metal oxides based on NiO and TiO 2 thin films which are able to detect 1000 ppm of hydrogen and to operate at 200°C. These films with thickness in the range of 50–100 nm were prepared by DC reactive magnetron sputtering on alumina and silicon substrates. The XRD measurements revealed polycrystalline character of annealed thin films at 600°C, whereas as-deposited samples were confirmed to be amorphous. Sensor structures based on NiO/TiO 2 /Si worked at very low operation temperature of 150°C though their responses to hydrogen appear lower relative sensitivity in comparison with those prepared from single oxides.

Novel pyrolyzed photoresist film (PPF) electrodes for application in electroanalysis have been prepared by pyrolysis of various photoresists on alumina substrates and characterized for their electrical, microstructural and electrochemical properties. As a support, the PPF electrodes were successfully applied for the determination of heavy metals (Pb, Cd and Zn) in an aqueous solution by square wave anodic stripping voltammetry (SWASV) on in situ formed bismuth film electrodes (BiFEs) with or without Nafion-coating. Selected parameters of Nafion film preparation (thickness, curing temperature) on the analytical performance of Nafion-coated BiFEs were investigated. Since the concentration of Bi(III) used for formation of the bismuth film influences the height of the stripping peaks, the bismuth to target metals concentration ratio had to be optimized in the range from 1 to 50. 2 × 10 −6 mol/L concentration of Bi(III) was chosen for the target metals concentration range of 1 × 10 −8 –1 × 10 −7 mol/L. By using the bare and the Nafion-coated BiFEs in simultaneous determination of target metals it has been found that the analytical sensitivities for Pb(II) and Cd(II) were 2 times higher in comparison with non-coated BiFEs due to the synergistic effect of redox cycling and non-faradic cation-exchanging preconcentration in the Nafion film. In the best case, the detection limits were estimated as 3 × 10 −9 , 6 × 10 −9 and 2.4 × 10 −8 mol/L for Pb(II), Cd(II) and Zn(II), respectively.

In this work, the optimal characteristics of etching TiO2 films in an inductively coupled plasma system with CF4/Ar plasma were investigated. The maximum etch rate of TiO2 was 93 nm/min at fixed 200 W of inductively coupled plasma power and the highest investigated value of RF chuck power of 150 W. Using the X-ray photoelectron spectroscopy the chemical reactions between TiO2 and F were analysed. It was found that the etching mechanism included ion-stimulated desorption of reaction products on the TiO2 surface and formation of a solid solution and non-volatile TiF3.

We present results on nanocrystalline NiO chemoresistive films which are able to detect 5 ppm of ethanol vapor in air and to operate at 250 °C. NiO films with 50 and 100 nm thicknesses were prepared by DC reactive magnetron sputtering on alumina substrates previously coated by Pt layers as microheaters and interdigitated electrodes. NiO-based sensors with 50 nm thickness exhibited three times higher relative sensitivity and were approximately 2 times faster than the sensor element with 100 nm thickness in the whole ethanol concentration range. These 50 nm thick NiO films are created by nanocrystals with lateral size of about 30 nm homogenously covering the Pt/alumina surface. On the other hand, NiO films with 100 nm thickness are porous, divided in parts and lapped by smaller grains (∼15 nm) in several overlayers.

Structural evolution of indium oxide thin films deposited at room temperature by reactive magnetron sputtering and annealing in a reducing atmosphere were investigated. The as deposited indium oxide (In 2 O 3 ) films showed a dominating randomly oriented nanocrystalline structure of cubic In 2 O 3 . The grain size decreased with increasing oxygen concentration in the plasma. Annealing in reducing atmospheres (vacuum, nitrogen and argon), besides improving the crystallinity, led to a partial cubic to rhombohedral phase transition in the indium oxide films. Annealing improved the optical properties of the indium oxide film and shifted the absorption edge to higher energies.

Top gated graphene field effect transistors with AlN and Si3N4 gate insulator materials were fabricated by plasma assisted deposition. Transistors with an AlN top gate insulator showed a reduced mobility and channel carrier density, whereas for the transistors with Si3N4 dielectric an increase of the mobility and a decrease of the channel carrier density was observed. The reduced carrier density can be explained by bond formation between the insulator and the graphene sheets. The different behaviour of the carrier mobility is due to defect passivation by H2 in case of Si3N4 and defect formation in the graphene channel for the AlN gate insulator. A reduced transconductance in top gate device configurations compared to the back gate configurations was observed, which can be caused by the Klein paradox or differences in the trap densities in the top gate insulators. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

TiO 2 thin films were prepared by DC reactive magnetron sputtering in a mixture of oxygen and argon on glass and oxidized silicon substrates. The effect of post-deposition annealing (300 °C, 500 °C and 700 °C for 8 h in air) on the structural and morphological properties of TiO 2 thin films is presented. In addition, the effect of Pt surface modification (1, 3 and 5 nm) on hydrogen sensing was studied. XRD patterns have shown that in the range of annealing temperatures from 300 °C to 500 °C crystallization starts and the thin film structure changes from amorphous to polycrystalline (anatase phase). In the case of samples on glass substrate, optical transmittance spectra were recorded. TiO 2 thin films were tested as sensors of hydrogen at concentrations 10,000-1000 ppm and operating temperatures within the 180-200 °C range. The samples with 1 nm and in particular with 3 nm of Pt on the surface responded to hydrogen fast and with high sensitivity.

This work describes the design, simulation, fabrication and characterization of a TiN/Pt microheater prepared on a GaAs micromechanical structure as a prospective device for micro-electro-mechanical system (MEMS) sensor arrays. Electro-thermal simulation was employed to verify the properties of the designed microstructure, which confirmed achievement of the operating temperatures in the range from 470 to 600 K with a heating power less than 25 mW. The average temperature gradient in the active area does not exceed 0.6 K/μm. Fabrication of GaAs suspended membranes was demonstrated, realized in two steps by combination of surface and bulk micromachining. Development and characterization of a microheater on a GaAs membrane is described. The mechanical stability of the heated multilayer membrane structure was tested and satisfactory mechanical stability of the hotplate was confirmed. The power consumption at an operating temperature of approximately 550 K is about 30 mW which is in good agreement with the value of about 22 mW obtained from electro-thermal simulation. The achieved thermal resistance value is 8.43 K/mW.

Bismuth film microelectrodes have a potential to replace toxic mercury used most frequently for determination of heavy metals by anodic stripping voltammetry. We developed diamond-like carbon microelectrodes doped by nitrogen as a support for bismuth electroplating. Bismuth-plated as well as bare microelectrode arrays were used for lead determination in aqueous solutions. The influence of many parameters on responses was investigated.

Two types of Schottky diodes were prepared on n-type silicon carbide (4H–SiC) substrates by deposition of ruthenium oxide (RuO2) Schottky contacts or ruthenium tungsten oxide (RuWO x ) Schottky contacts. The RuO2/4H–SiC and RuWO x /4H–SiC Schottky barrier diodes were examined first by current–voltage (I-V) measurements, which confirmed symmetry of the I-V characteristics. The ideality factor (n) is rather high (∼1.28/∼1.15) at the temperature 300 K, the current of saturation is I S ∼10 pA/∼7 pA and the Schottky barrier height is ∼1.13 eV/∼1.11 eV. After this diagnostic step, the samples were analysed by C-V and standard DLTS methods in the temperature range from 83 K to 450 K. In measured DLTS spectra were identified five deep levels ET1–ET5 (0.27, 0.45, 0.56, 0.58 and 0.85 eV) in RuO2/4H–SiC Schottky barrier diodes and three deep levels E1–E3 (0.36, 0.38 and 0.69 eV) in RuWO x /4H–SiC Schottky barrier diodes.

Boron oxide films were grown on silicon substrates by radio-frequency (rf) unbalanced magnetron sputtering of a boron target in argon–oxygen gas mixtures with different compositions. Microscopic analyses show that overall boron oxide films are amorphous. The film prepared at oxygen/argon flow rate ratio > 0.05 developed large crystallites of boric acid in localize areas of amorphous boron oxide matrices. These crystallites were unstable and at electron microscopic analysis they continuously transformed to a cubic HBO2 phase and then completely vanished leaving an underlying amorphous boron oxide film behind. The analyses indicate the coexistence of B6O, HBO2 crystallites and amorphous boron oxide matrices. Fourier transform infrared (FTIR) spectra revealed spectral bands of BOH, BO, BOB and BH groups. Nanohardness and elastic modulus of a film prepared at low oxygen concentration approach 30 and 300 GPa, respectively. These parameters however vary with deposition conditions.

Nanocrystalline NiO thin films were deposited by dc reactive magnetron sputtering in a mixture of oxygen and argon and subsequently coated by Au on a NiO film surface. Very thin Au overlayers with a thickness of about 1 and 7 nm have been prepared by magnetron sputtering. Then, the surface modified NiO films have been analysed by TEM, EDX and SEM. NiO thin films showed a polycrystalline structure with the size of nanocrystals ranging from a few nanometers to 10 nm. Electrical responses of NiO-based structure towards hydrogen have been measured.

Nanostructured NiO thin films were prepared by dc reactive magnetron sputtering in a mixture of oxygen and argon and subsequently coated by Pt on an NiO film surface. Pt very thin overlayers with a thickness of about 3 and 5 nm have been deposited by magnetron sputtering. The microstructure and surface morphology of the samples have been analysed by XRD and by SEM and AFM, respectively. The electrical responses of the NiO-based sensors towards hydrogen concentration have been also considered. The thickness of the Pt thin layers seems an important parameter in determining the properties of the NiO films as hydrogen sensors.

Nanocrystalline NiO thin films were prepared by dc reactive magnetron sputtering in a mixture of oxygen and argon and subsequently coated by Pt on an NiO film surface. Very thin Pt overlayers with a thickness of about 3 and 5 nm have been deposited by magnetron sputtering. Then, the modified NiO films have been analyzed by TEM, EELS and AES. NiO thin films showed a polycrystalline structure (fcc NiO phase) with the size of nanocrystals ranging from a few nanometres to 10 nm. TEM observations both of unmodified and Pt-modified NiO films revealed that they were formed by nanocrystals and an amorphous phase. Uniformly distributed Pt particles were produced on top of the NiO surface. According to AES measurements, the presence of Ni in the spectra recorded from Pt pad indicated that the Pt layer has discontinuous nature. Electrical responses of NiO-based sensor structures towards hydrogen have been measured.

In this paper, we present the results concerning the Pt surface modification of nickel oxide thin films deposited by dc reactive magnetron sputtering. Pt very thin overlayers with a thickness of about 3 and 5 nm have been sputtered on the top of NiO samples. The surface structure and morphology of the samples have been analysed by X-ray diffractometer (XRD) and by scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. The electrical responses of the NiO-based sensors towards different H2 concentration (500–5000 ppm) have been also considered. The Pt-modified NiO samples showed an enhancement of the response towards H2 as compared to the unmodified NiO sample. The thickness of the Pt thin layers seems also an important parameter in determining the properties of the NiO films as H2 sensors.

We present properties of nitrogen-doped amorphous silicon carbide films that were grown by a plasma enhanced chemical vapour deposition (PECVD) technique and annealed by pulsed electron beam. Samples with different amounts of N were achieved by a small addition of ammonia NH3 into the gas mixture of silane SiH4 and methane CH4, which were directly introduced into the reaction chamber. The actual amount of nitrogen in the SiC films was determined by Rutherford backscattering spectrometry (RBS). A simulation of the RBS spectra was used to calculate the concentration of carbon, silicon and nitrogen.

We present the pulsed de magnetron sputtering method in which a nickel target is sputtered in a mixture of argon and reactive oxygen gas. The flow modulation of oxygen is proposed to enhance the deposition process in the preparation of the oxide films. The flow rate of oxygen is modulated periodically in time and during deposition when oxygen flows is cut off to remove the oxide formed on the target. A modulated deposition process was monitored directly by optical emission spectroscopy, measuring the deposition rate and the partial pressure. The effect of the different oxygen flow, which was changed periodically, changes with time on the target potential and the deposition rate were investigated. The variations of the Ni/O atomic ratios in NiO films were revealed by SIMS method.

In this paper we present the results concerning the characterisation of nickel oxide thin films deposited by d.c. reactive magnetron sputtering. Different NiO thin films have been prepared by changing some deposition parameters, as the oxygen content in the reactive plasma and the sputtering mode (metal- or oxide-sputtering mode). The structure and surface morphology of the samples have been analysed by XRD and by atomic force microscopy and scanning electron microscope, respectively. The electrical responses of the NiO films towards NO 2 have been also considered. NiO thin films showed good responses to low NO 2 concentrations (1–10 ppm) with a maximum at 160 °C operating temperature.

Nickel oxide (NiO) thin films have been prepared by dc reactive magnetron sputtering from a metallic Ni target in an Ar+O 2 mixed atmosphere in two sputtering modes. The oxygen content in the gas mixture varied from 15 to 45%. Rutherford backscattering spectrometry (RBS) and X-ray photoelectron spectroscope (XPS) investigations have been used for the study of the chemical composition and to detect different chemical states of bond elements. TEM observations revealed a dense fine-grained structure with the grain size in the range 4–10 nm. Atomic force microscopy (AFM) showed that the surface morphology NiO films can be modified by the process parameters as the oxygen content and the pumping speed. Scanning electron microscope (SEM) observation and energy dispersive X-ray (EDX) analyses revealed uniform morphology and homogenous dispersion of NiO, Pt and Al 2 O 3 phases. In addition, the NiO thin films were tested in order to investigate their response to CO in the range 50–200 ppm at different operating temperatures.

Nickel oxide (NiO) thin films were prepared by dc reactive magnetron sputtering from a nickel metal target in an Ar+O2 mixed atmosphere in two sputtering modes. The oxygen content in the gas mixture varied from 15% to 45%. The films prepared in the oxide-sputtering mode were amorphous while the films in metal-sputtering mode exhibited polycrystalline (fcc) NiO phase. In this case TEM observations showed a dense fine-grained structure with the grain size in the range 4–10 nm and AFM micrograph showed a rough surface with RMS=2.21 nm. We have found that good NiO stoichiometric films are obtainable with a polycrystalline (fcc) structure at 40% oxygen content in the metal-sputtering mode.

NiO thin films were prepared by dc reactive magnetron sputtering with thicknesses of about 50 and 100 nm on alumina and KCl substrates. The deposited films were annealed in a furnace at 500°C in nitrogen atmosphere for 2 hours. From XRD and TEM investigations were found that annealed NiO thin films have a polycrystalline structure with the size of grains below 25 nm. The electrical responses of NiO sensor structures towards different ethanol, acetone and toluene concentrations have been measured. It was found that the thickness of NiO films is an important parameter in determining the sensitivity of prepared gas sensors.

The indium oxide films were deposited by dc reactive magnetron sputtering from In target on unheated Si substrate with oxygen flow in the ranging from 40 to 80 sccm. The deposited films were annealed in a conventional tube at T=400°C for 1 hour in N 2 atmosphere. Measured absorption coefficients of all indium oxide films were in the range the values of 2.6÷12.5×106 m−1. It was found that calculated values of the direct band gap and indirect band gap depend on oxygen content in the sputtering gas mixture. Electrical resistivity increased from 6.8×103 to 28.5×103 Ωcm with increasing oxygen flow 40 – 80 sccm. Finally, the correlation between optical properties and surface roughness of examined samples was identified.

The multilayer compound thin films, consisted of metal oxides (TiO 2 and NiO) prepared by dc magnetron sputtering technique, have been studied. The structural, compositional, electrical and gas sensing properties have been investigated by XRD, GDOES and Van der Pauw method considering changes in layout, annealing temperature and addition of Au noble metal catalyst. The Au modified compound oxides exhibit fast response and enhanced sensitivity to hydrogen at low operating temperatures.