The semiconductor material of ternary alloy of Indium and Aluminum nitride (InxAl1-xN) has interesting properties for potential optoelectronic applications and solar cells as well. In the present research, layers of In0.63Al0.37 N were synthesized using the DC reactive sputtering magnetron technique, on p-type silicon substrates (100), ITO/PET, and ITO/Glass. The reason why an intermediate layer of ITO was placed on the PET and Glass substrates is that possibly in an InAlN thin-layer solar cell, the ITO would fulfill the role of Conductive Transparent Oxide (CTO). This CTO would be located between the window layer and the transparent substrate. On the other hand, in the case of a hetero-union solar cell, InAlN-n would be located on the Si-p material, in order to form the p–n junction. Therefore, the present work allowed us to study subsystems in which the InAlN would be part of the window layer in three different types of solar cells.

The Inx Al1-xN heterojunction exhibits interesting features that make it a promising candidate for designing solar cells. Nevertheless, there are no studies about how the three types of band alignment (straddled, staggered and broken gap) affect the Inx Al1-x N heterojunction. In this work, Inx Al1-x N on commercial p-type silicon heterojunction was studied using computational simulation in solar cells. The main objective was to study the band alignment to maximize the efficiency of the cell for building experimental devices in the future. The thickness of the silicon layer remained constant at 500 μm. The thickness of Inx Al1-x N was varied between 10 nm and 100 nm, and the concentration of InN between 20% and 90%. It was found that the band alignment impacted on the open circuit voltage, the short circuit current density, the efficiency of the solar cell, and the quantum efficiency. It is theoretically concluded that a n-Inx Al1-x N/p-Si type heterojunction solar cell can be designed, with a maximum efficiency of 26.6%, adjusting the thickness of the InAlN layer to 10 nm and the InN concentration of 70%. This valuable result shows a good prospect for the manufacture of experimental devices.

The indium and aluminum nitride (InxAl1-xN) semiconductor material was postulated in 2008 as an excellent candidate to produce solar cells. In this research, amorphous layers of InxAl1-xN (0.55 <= x <= 0.60) were synthesized using the RF sputtering magnetron technique, and then studied for their possible use in photovoltaic applications. Physical, structural, morphological, optical, and electrical properties were studied. The amorphousness was checked by XRD difractograms. Samples have very smooth surfaces, with very low roughness values, according to AFM and SEM techniques. Electrical properties of the InAlN films were studied using Van Der Pauw technique and Hall Effect parameters. The volumetric carrier concentration decreases when InN fraction mole increases. The mobility values range between 6 x 10(-2) and 5 x 10(-1) cm(2) V-1 s(-1), which are lower than those obtained for crystalline and polycrystalline samples. The obtained band gap values could be used in both the absorbing layer and the window layer in solar cells (1.9 eV-2.3 eV). Interestingly, this figures of Eg are very close to the previously obtained values for polycrystalline samples. The optical absorption coefficients were high compared to the materials currently used in solar cells (similar to 10(5) cm(-1)). This implies the possibility of using thinner layers in photovoltaic devices based on InxAl1-xN.

En el Laboratorio de fisica del plasma de la Universidad Nacional de Colombia sede Manizales se ha construido un reactor industrial, con el fin de recubrir piezas del herramental de las maquinarias para mejorar su desempeno y vida util. Las variantes tecnicas se fundamentan en el equipamiento auxiliar. Una de ellas es el sistema arbol porta muestras que debe hacer girar los objetos a procesar para conseguir la homogeneidad del recubrimiento en todas las piezas, en un movimiento de traslacion y rotacion planetario, con una velocidad que pueda ser controlada de acuerdo al tipo de muestra y de recubrimiento que se desee realizar para eliminar en un alto porcentaje las micro-gotas propias de la tecnica. Un factor importante en el diseno del sistema de giro es el torque del rotor del motor empleado, el cual depende del peso del arbol, de las piezas a recubrir, el rozamiento entre los engranajes y de estos con las bandejas. Con este fin se implemento un sistema compuesto por acoples electronicos (variadores de velocidad) y acoples mecanicos (reductores y juego de pinones). De esta manera se puede variar la velocidad de rotacion de la carga entre 0 y 60 rpm. .

TiAlN films were deposited on ASTM A36 steel by RF reactive sputtering using a TiAl alloy target Ti/Al - 60/40 at.% in an Ar+N-2 atmosphere. The films were produced at two different pressures relation (P-N2/P-Total), 0.05 and 0.1 with a constant argon pressure. The coatings were gown on ASTM A36 steel samples at a substrate temperature of 230 degrees C with different initial conditions: as delivered, hard and quenched, plasma nitriding, previously coated with Ti or TiN. The TiAlN films displayed mainly a Ti2Al3N composition with a (h00) preferential orientation, which increases by increasing the pressure ratio from 0.05 to 0.1. Samples with the higher homogeneity obtained with a pressure ratio of 0. 1 also displayed the highest values of hardness (around 2500 HK), corrosion and wear resistance and the highest adherence was observed in samples coated at a pressure ratio of 0.05. (c) 2006 Elsevier B.V. All rights reserved.

Thin films can be grown in super-lattice, multilayers and graded form, having each one advantages and disadvantages. The difference between multilayer and graded coatings is the interface. In multilayers the interface is abrupt and in graded coatings it is diffuse. The interface influences many chemical and physical properties of the materials, and its choice depends on the application. Graded coatings have the advantage of having gradual properties such as thermal expansion coefficient and lattice parameter, avoiding adherence problems due to good match between their component materials In this work the comparison between some properties of coatings grown as multilayer and graded is performed. The materials are produced using the sputtering DC technique because of its facility to control the deposition parameters and generate a slow growth. The target is a disc of titanium and the samples are made of stainless steel 304. The working gases are argon, nitrogen and methane, which are mixed according to the material to be produced, i.e. Ti layer is grown with argon, the TiN film is produced with a mixture of argon and nitrogen, and the TiCN material is obtained mixing argon, nitrogen and methane. These materials are characterized with AFM in order to determine gram size and with XPS studying the chemical composition and performing depth profiles.

At the Plasma Physics Laboratory in the Universidad Nacional de Colombia at Manizales (Colombia) an industrial reactor has been constructed for the purpose of covering pieces of the tooling of machineries to improve its performance and useful life. The technical variants are based on the auxiliary equipment. One of them is the sample-carrier system cam that must rotate the objects to be processed to obtain coating homogeneity in all the pieces, in a movement of transfer and planetary rotation, with a speed that can be controlled according to the type of sample and coating desired to eliminate in a high percentage the micro-drops of the technique. An important factor in the design of the turn system is the rotor torque of the motor used, which depends on the weight of the cam, the pieces to be coated, the friction between the gears and of these with the trays. With this aim we implemented a system made up of electronic couplings (speed controller) and mechanical couplers (reducers and pinion set). This way the speed of rotation can be varied between 0 and 60 rpm.

In this work the study of plasma characteristics by means of two of the most common techniques employed by the scientific community dedicated to the experimental plasma research is presented. The plasma was generated in a vacuum reaction chamber which was filled with hydrogen gas. Inside the chamber, two opposite electrodes were placed: the cathode, which was formed by a target of highly oriented pirolitic carbon and the anode. The electron temperature Te and the electron density ne were measured by using optical emission spectroscopy and electrostatic double probe, obtaining very close values for each case. Te was calculated as approximately 0.7eV and ne of the order of 1013cm−3. The optical emission measurement allows one to identify the substances that are in the plasma like C I, C II, C III, H I and H2 and some possible reactions. The double-probe technique showed the plasma potential of about 24V. The characteristic curve of the double probe exhibited oscillational plasma instabilities which could be attributed to the charge density variation or other factors, such as the employed AC signal and the geometric probe.

This paper presents an investigation regarding influence of substrate temperature during deposition on the characteristics of TiN/TiC bilayers grown by plasma-assisted pulsed arc discharge. The substrate temperatures were 50, 100 and 150°C. The gases used in the experiment were N2 for TiN and CH4 for TiC. These coatings were studied by X-ray diffraction techniques determining the variation of the lattice parameters for each film. The Scherrer equation was used to calculate the crystallite size and the micro-strain. The X-rays analysis showed an increase in the substrate temperature made the formation of TiC in (200) orientation favorable. The sample grown at 50°C presented low crystallinity and it was increased as the substrate temperature increases. Using a scanning probe microscopy, with atomic force microscopy, phase detection microscopy and force modulation microscopy modes, the morphology of the deposited layer was studied and macro-particles were observed using gray scales to identify differences in the friction coefficient and material composition in the coatings. It has been found that the increment of the substrate temperature decreases the condensation of microdroplets on the surface. Lateral force microscopy was used to calculate friction coefficient of the TiN and TiC monolayers and we found that the friction coefficient is smaller for TiC than for TiN.

TiAlN films were deposited on ASTM A36 steel by RF reactive sputtering using a TiAl alloy target Ti/Al — 60/40 at.% in an Ar + N2 atmosphere. The films were produced at two different pressures relation (PN2/PTotal), 0.05 and 0.1 with a constant argon pressure. The coatings were grown on ASTM A36 steel samples at a substrate temperature of 230 °C with different initial conditions: as delivered, hard and quenched, plasma nitriding, previously coated with Ti or TiN. The TiAlN films displayed mainly a Ti2Al3N composition with a (h00) preferential orientation, which increases by increasing the pressure ratio from 0.05 to 0.1. Samples with the higher homogeneity obtained with a pressure ratio of 0.1 also displayed the highest values of hardness (around 2500 HK), corrosion and wear resistance and the highest adherence was observed in samples coated at a pressure ratio of 0.05.

The X-ray diffraction technique was used to study the influence of the temperature on a crystal phase of W/WC bilayer produced by the plasma-assisted pulsed arc discharge. In order to grow the films, a target of W with 99.9999% purity and stainless-steel 304 substrate were used. For the production of W layer, the reaction chamber was filled up with argon gas until reaching a 300Pa and the discharge was performed at 270V with 3 pulses. The WC layer was grown in a methane atmosphere at 300Pa and 275V discharge voltage with 4 pulses. The active and passive times of the pulsed discharge were 1 and 0.5s, respectively. The influence of post-annealing temperature of their crystal phases was studied at the post-annealing temperatures up to 600°C. As-grown layer comprised of mixed phases WC, W2C and W. The post-annealed layer also comprised of the mixed phases of WC, W2C and W at annealing temperatures below 600°C. At the annealing temperature above 600°C, XRD diffractograms showed only substrate and W peaks, and tungsten carbide peaks were not observed, but the presence of WO phases were detected for an annealing temperature of 600°C. XPS analyses showed the presence of WC before the annealing process and the existence of C–C bond that is considered responsible for the high polycrystallinity of the material was also detected. The XPS showed the formation of WO2 and WO3 without the presence of WC for post-annealing at 600°C.

Tungsten carbide is considered a very important material used for industrial applications due to their high hardness. In this work the production of W/WC coatings used a repetitive pulsed arc system is employed. During the grown process, the substrate temperature is varied in order to identify the influence of this parameter in the structure, composition and morphology of the coatings. The layer of W is grown to improve the adherence of the WC material on the stainless steel 304. To grown the coatings, it was used a W target in the cathode. The gas of work is methane and as it is knew, to use a gas as precursor for WC production causes the apparition of different phases as WC and W2C. The power supply allows varying the active and passive time of pulses, which in this case have a value of 1s. the coatings produced are characterized by X-ray diffraction (XRD), X-photoelectron spectroscopy (XPS) and scanning probe microscopy (SPM). All of these techniques allow determining properties such as chemical composition, structure, stoichiometry, thickness and grain size.

ZrN films were grown by a plasma-assisted repetitive pulsed vacuum arc discharge. The films were grown on 304 stainless steel substrates. To grow the coatings, a cathode of Zr was used. The system is made up by a reaction chamber with two electrodes placed face to face. A pulsed power supply is used to generate the discharge. The coatings were grown, varying the substrate temperature (Ts) between 50°C and 260°C. The pressure into the chamber was 3mbar and the voltage of the discharge was 270V. XRD technique was employed to study the coatings, observing variations of some parameters as crystallographic texture and crystallite size, as a function of Ts. Morphological characteristics were analyzed by means of an atomic force microscopy (AFM), determining the thickness and the grain size, where it is possible to observe the influence of the surface and strain energies which have great relationship with Ts.

In this work the determination of plasma parameters of a pulsed-arc discharge by using an electrostatic double probe is presented. The system to generate the plasma is composed mainly of a reaction chamber, where the electrodes of different materials (Ti, Zr, Al) were placed in order to identify the variation of the plasma parameters when the cathode material is changed. An automatic system has been implemented for acquiring data starting from the bias of a double electrostatic probe. This system allowed registering complete curves of current-voltage in relatively short times (≈30ms). The electron density ne and electron temperature Te can be extracted from the I-V characteristic curves obtained. The advantage of this technique is its facility to provide the whole quantity of “in situ” information, which can be compared with the theoretical results using numeric methods for the I-V curves simulation. By means of a suitable fit this allowed the determination of the plasma parameters. The values obtained for Te were in the order of 1eV and for ne of about 1013cm−3. A significant variation for ne was not found.

W/WC films were grown by the PAPVD repetitive pulsed vacuum arc technique on 304 stainless steel substrates. To produce the coatings, a target of W with purity of 99.9999% was used. The system is composed by a reaction chamber with two opposite electrodes placed inside it. The target is located on the cathode and the samples on the anode. A pulsed power supply is used to generate the discharge. For the production of the W layer, the chamber was filled with Ar gas at a pressure of 3 mbar, and the voltage of the discharge was 270 V with 3 pulses. WC films were grown in an atmosphere of methane at 3 mbar and a voltage discharge of 275 V with 4 pulses. The active and passive times of the discharge were 1 s and 0.5 s, respectively. XRD technique was employed to study the coatings, to study the present phases and the crystallographic orientation of the films, the XRD analyses were carried out varying the temperature of the system-coating-substrate between room temperature and 600 °C, when the WC coatings are degradated, leaving just the tugsten. XPS analyses present the apparition of WC, WO and WO2 compounds. AFM analyses allowed to measure the morphological properties and the thickness around 3 µm. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

TiN/TiC bilayers were produced using a PAPVD plasma assisted vacuum arc system. During the production process, both TiN and TiC coatings, pressure into the reaction chamber, voltage of the discharge and interelectrode distance were maintained fixed for each case. TiC coatings were grown varying the temperature of the substrate at 50 °C, 100 °C and 150 °C, while the TiN coatings were grown maintaining at room temperature. The analyses were carried out by using X-ray diffraction, identifying FCC phases and orientation in planes (111), (200), (221) and (311). XPS characterization displayed the formation of TiC and TiN by means of the Ti2p, C1s and N1s peaks narrow spectra study. A great influence of the substrate temperature in the films was observed, specially in the transition from amorphous to crystalline phases. The lattice parameters also present changes as a function of the temperature. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

ZrN films were grown by the PAPVD method in the pulsed arc technique; bilayers were grown on stainless steel substrates by using a repetitive pulsed vacuum arc system. To produce the coatings, a target of Zr with a purity of 99.99% was used. The system is composed by a reaction chamber with two opposite electrodes placed inside it. The target is the cathode and the samples of stainless steel are the anode. A pulsed power supply is used to generate the discharge. The coatings were grown, varying the temperature of the substrate between 50 degrees C and 260 degrees C. The pressure into chamber was 3 mbar and the voltage of the discharge was 270 V. XRD technique was employed to study the coatings, observing changes on the lattice paramenter and intensity variations of the crystallographic planes, as a function of the substrate temperature. Morphological characteristics were analized by means of an Atomic Force Microscopy (AFM), determining the thickness and the grain size. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

TiN films were produced by d.c. reactive sputtering technique. The TiN coatings were grown on AISIM2 steel substrates with different initial conditions: annealing and quenching; annealing, quenching and previously coated with Ti with different thickness; annealing, quenching and plasma nitriding, The samples were produced in a mixture of 20% of nitrogen and 80% of argon at a pressure of 8 x 10(-2) mbar and 200 degrees C of substrate temperature. The deposition time was varied systematically between I and 3 h. Moreover, the coatings were produced at different conditions of voltage and current: (1) 450 V and 250 mA, (2) 475 V and 275 mA and (3) 475 V and 225 mA. The micro-hardness analyses showed the greatest hardness for films grown at the higher d.c. power during 3 h.TiN coatings deposited on substrates previously nitrided by plasma with a Ti interlayer showed a marked increase in the micro-hardness, with regard to the films grown without a plasma nitriding process. The phases and the crystalline structure were determined by X-ray diffraction (XRD). A FCC structure with a preferential orientation in the (200) plane was observed. Scanning electron microscopy (SEM) was used to determine the thickness of the nitrided diffusion zone. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DC pulsed arcs, between face to face opposite electrodes of graphite and stainless steel at pressures varying from 50 to 500 Pa into nitrogen environment, with a current and voltage of 300 A and 167 V, respectively, and a pulsed arc time of 30 ms were produced.Several consecutive craters, created by explosive way and by inclusions over the graphite cathode were found. These are located principally at the outskirts of the center and at the half of the graphite cathode radius; they are originated because of the cathode spots chaotic movement. The most representative craters have sizes over than 300 mu m and some melted sectors were observed by means of the SEM technique, corroborating that there are temperatures higher or equal than the melting point of the graphite. The film surface is composed by small spheres with structures similar to the ones in the cauliflower diamond. Craters in some melted sectors on the anode surface were observed. (c) 2005 Published by Elsevier B.V.

Bilayers of TiN/BN were produced by using a PAPVD (Plasma Assisted Physical Vapor Deposition) pulsed vacuum arc system. The equipment is formed by a reactor composed by a vacuum chamber with two face-to-face electrodes and an RLC circuit to produce the arc discharge. To obtain the BN coating a target of h-BN was used placed on the cathode and a substrates of silicon placed on the anode. The work gas was nitrogen at a pressure of 4.4 x 10(-1) mbar and a voltage of 240 V. In order to improve the adherence of the BN film, an interlayer of TiN was grown. In this case the chamber was filled with N-2 to produce the TiN coating, with a pressure of 1.7 mbar and a voltage of 300 V. By means of XRD (X-ray diffraction), the existence of TiN was determined finding different crystalline orientation in FCC phase. An FTIR (Fourier Transform Infrared Spectroscopy) was employed to determine sp(3)/sp(2) bonding ratio in the BN film.By plotting I- V curves the electrical properties of the bilayer were studied, observing a semiconductor behavior and this result was compared to the silicon substrate without coating. (c) 2005 Elsevier Ltd. All rights reserved.