Roberto Sangines

Consejo Nacional de Ciencia y Tecnología · Centro de Nanociencias y Nanotecnología UNAM

Deposition parameters of silicon nitride in reactive direct-current magnetron sputtering were studied in two different chambers in order to establish a characterization protocol assisted by optical emission spectroscopy. Different discharge powers, working pressures and gas proportions (N2:Ar) were used to create characterization curves to identify...

The optical plasma spectroscopy was correlated with the optical properties of SiN x O y synthesized by reactive magnetron sputtering. A principal component analysis of the system data was developed to monitor the synthesis of inhomogeneous filters.

It is proposed that the pursuit of optimal parameters for the synthesis of TiN thin films by reactive sputtering can be simplified by implementing plasma optical emission spectroscopy in real time. Emission from Ti and neutral and ionized species of Ar and N2 were obtained at different deposition conditions such as supplied power and gasses flow ra...

A good Low-Emissivity (Low-E) filter coated on glass reduces the amount of heat coming from solar light into the building, thus the expenses in electricity for air conditioning are reduced. Standard Low-E filters contain a Silver layer between two dielectric thin films due to its high reflectance of infrared wavelengths; however, one of the major s...

Target poisoning in reactive sputtering is one of the biggest problems in the coatings industry. In this work, we use the Co-Sputtering Simulation Reactive mode software, Co-SS Rm, to present a different solution of the compound formation both on the target and on the substrate, based on the comparison of the simulations with the thickness measure...

We present a thorough study of the target-cleaning phase to estimate the healthiness of the target in a direct current (DC) magnetron sputtering deposition. The study is based on real-time plasma monitoring by means of optical emission spectroscopy during a traditional cleaning phase in an Ar atmosphere. In this work we demonstrate that intensities...

The emission of laser-induced plasma on aluminum targets in air was investigated with nanosecond- and picosecond-pulsed Nd:YAG laser emitting at the fundamental wavelength. Orthogonal double pulse in pre-ablation and reheating configurations was also performed where the picosecond laser was employed to ablate the target. Ablation fluences were kept...

The evolution of laser induced ablation plume on aluminum targets has been investigated in orthogonal pre-ablation double pulse scheme at atmospheric pressure from the earliest stages of plasma evolution. Time-resolved emission spectra from neutrals, singly- and doubly-ionized species obtained with the double pulse experiment have been compared wit...

In this work the detection sensitivity of Cu, Mg, Pb, Hg, Cd, Cr and Fe traces in water and ice samples has been investigated under the same experimental conditions by using laser-induced breakdown spectroscopy. Plasmas were generated by focusing the fundamental output of a Nd: YAG laser on target surfaces. Limits of detection in ice were found to...

Laser-induced plasma was produced on preheated (up to 500 °C) aluminum targets in air with a nanosecond-pulsed Nd:YAG laser emitting at 1064 nm. Plasma was generated for laser pulse energies ranging from 60 to 800 mJ and the spatially and time-integrated emission was collected as the sample temperature was increased. Electron temperature was found...

Orthogonal double-pulse laser ablation on aluminum-based alloy target at atmospheric pressure was investigated by time-resolved optical emission spectroscopy. Studies were performed as a function of the distance from the first pulse plasma induced in air to the sample surface. Double-pulse experimental results were compared to single-pulse laser ab...

Orthogonal double pulse laser ablation on aluminum target at atmospheric pressure was studied by time-resolved optical emission spectroscopy, shadowgraphy and two-color interferometry. Studies were realized as a function of the distance from the first pulse plasma induced in air to the sample surface. The evolution of the electron and neutral parti...

The evolution of plasma composition, electron temperature and deposition rates of high-power impulse magnetron sputtering (HIPIMS) of a titanium target have been studied by optical emission spectroscopy and deposition on a crystal oscillator, for pulse lengths of 50μs and 100μs over a range of voltages. The observations indicate a strong power depe...

A photoacoustic technique was used as an alternative method to monitor the crater volume and its role in the emission line intensification in double-pulse pre-ablation configuration. The crater volume was measured using confocal microscopy and correlated with the changes in the photoacoustic signal. Laser emission spectroscopy was used to character...

A monochromator∕Fizeau interferometer∕intensified CCD camera system is described that was developed for the measurement of the shape of spectral lines that are rapidly time varying. The most important operating parameter that determines the performance of the instrument is the size of the entrance aperture as this determines both the light throughp...

Time resolved optical diagnostic techniques were used to study the production of highly ionized species in aluminum plasma produced by a centered-triggered high-current pulsed cathodic arc. Controlling the spacing between cathode spots enabled a correlation between a reduction in the mean charge state and an increase in the spacing of cathode spots...

The plasma transport and loss mechanisms in a magnetically filtered pulsed cathodic vacuum arc operating at high currents were studied. The system efficiency was determined according to a system coefficient, defined as the ion saturation substrate current to cathode current ratio, for a comprehensive set of cathode currents, confining magnetic fiel...

The plume dynamics of the pulsed-laser ablation of iron at atmospheric pressure has been studied by resonant absorption photography. Fe I and II species were illuminated with an OPO set tuned to the correspondent resonant absorption transitions. Images show that the neutral and singly ionized species last about 50 and 2 mus, respectively.

Studies of plasma behavior produced by a filtered high current pulsed cathodic vacuum arc system are reported. Titanium plasma is initiated from the cathode by surface flash over triggering at the centre of the cathode disk. The multiple arc spots move outwards due to their mutual repulsion and the arc current pulse is terminated as the arc spots...

Cross-beam pulsed laser ablation with two delayed lasers is performed on two perpendicular graphite targets. The time delay between lasers is varied by up to 5 μs, and physical changes on the second plasma, due to the interaction with the first generated one, are determined by time resolved optical emission spectroscopy.

Plasma emission produced by Dual Pulsed Laser Ablation (DPLA) on two perpendicular graphite targets, separated 3 mm, was analyzed. Ablation was carried out in vacuum (10−6 Torr) by an excimer (248 nm) and a Nd: YAG (1064 nm) lasers, delayed up to 20 μs. Spatial and temporal measurements were performed by time resolved optical emission spectroscop...

The dynamics of the interaction between two plasmas induced by cross-beam pulsed-laser ablation was analyzed by time resolved optical emission spectroscopy and fast photography. The plasmas were created in vacuum by irradiating two perpendicular graphite targets with an excimer 248 nm and a Nd:yttrium-aluminum-garnet 1064 nm laser. In this configur...

Plasma generated by dual pulsed synchronized laser ablation onto two perpendicular graphite targets in vacuum was analyzed by two-color interferometry and fast photography. The delay between the firing of the lasers was varied up to 5 μs. Electron and neutral densities values at 0.5 mm from the second pulse target were 1.3×1018 cm−3 and 3.0×1019 cm...

Laser ablation in addition for thin film growing is also used for analytical techniques as Laser Induced Breakdown Spectroscopy and for applications as simulation of natural lightning. In this work we present several diagnostic techniques such as probe beam deflection, shadowgraphy, interferometry, pulsed laser photoacoustic and the electrical pert...

1] Lightning activity is typically generated by explosive volcanic activity. In this work we report an experimental simulation of a volcanic lightning by focusing into a basaltic rock the emission of a pulsed Nd: YAG laser in air at atmospheric pressure (laser ablation). The temporal evolution of air breakdown in an ash plume was studied by emissio...