S. Orlando

AIN thin film deposition by pulsed laser ablation of Al in NH3

Abstract Aluminium nitride films were synthesized by reaction of laser-evaporated Al in NH3 atmosphere. Optical multichannel emission spectroscopy (OMA) and intensified charge coupled device (ICCD) imaging have been applied to in situ identification of deposition precursors in the plasma plume moving from the target to the substrate. Mass spectrometry has also been used to detect ionic species ejected from an Al target in a mixture with NH3. Thin films prepared by this method were characterized by conventional techniques such as Auger, energy dispersive analysis of X-ray (EDAX), scanning electron microscopy (SEM), and X-ray diffraction. Highly oriented films of AIN (100) on Si (100) were identified.

Pulsed laser ablation of NbN/MgO/NbN multilayers

Abstract NbN/MgO/NbN multilayers have been grown by pulsed laser ablation in pure N2 and O2 atmospheres. A Nd:YAG laser, operating at λ=532 nm, pulse width 10 ns, and energy density in the range 1–2.5 J/cm2, was used. The laser beam was focused at an angle of 45° on Nb and Mg metallic targets. A rotating multiple-target holder system allowed in-situ depositions of the multilayers. The samples were grown on SrTiO3 (100) substrates 5 cm from the target and held at 550°C (NbN) and 250°C (MgO). The morphology and structure of the deposited multilayers were verified by XRD, EDS, as well as electrical measurements.

Composition and gas dynamics of laser ablated AlN plumes

Abstract The formation, composition and propagation of pulsed laser produced plasma plumes from an AlN target have been studied in real time by spatially and temporally resolved optical spectroscopy. The mean front velocity has been measured and appears to be slightly slower in the presence of added gas than in vacuum. In the initial stage of expansion, this velocity is almost the same for all neutral particles in the plume in the initial stage of expansion. Velocities of neutral and ionic species have been measured by their time of arrival from the target to a quadrupole mass spectrometer and their expansion beam Maxwell-Boltzmann (MB) temperature determined. The plume electronic temperature has been determined by assuming a local thermodynamic equilibrium of the emitting species.

Titanium nitride thin films deposited by reactive pulsed-laser ablation in RF plasma

Abstract Titanium nitride thin films were deposited on Si (100) substrates by pulsed laser ablation of a titanium target in a N 2 atmosphere (gas pressure approx. 10 Pa) using a doubled frequency Nd:YAG laser (532 nm) also assisted by a 13.56-MHz radio frequency (RF) plasma. Deposition was carried out at various substrate temperatures ranging from 373 up to 873 K and films were analyzed by X-ray diffractometry, scanning electron microscopy and optical emission spectroscopy. A comparison between the ‘normal’ pulsed laser deposition (PLD) and the RF plasma-assisted PLD showed the influence of the plasma on the structural characteristics of the thin films.

NbN superconducting thin films grown by pulsed laser ablation

Abstract NbN superconducting thin films have been grown by using pulsed laser ablation in a N 2 pure atmosphere. The X-ray spectra indicate that highly oriented superconducting NbN films having a FWHM of the 002 reflection narrower than 0.5°, has been obtained. Critical zero resistance temperature T c higher than 16.3 K and resistivity ratio ≈ 1.3 were measured as well as critical field of 12 T at LHe temperature on the high quality films. Transport critical current density J c , measured on a patterned film with a 50 μV cm criteria, gave an extrapolated value of J c0 higher than 1 × 10 7 A/cm 2 computed by using a Kim Andersen model. Preliminary photoemission spectroscopy measurements in the presence of N 2 background gas indicate some reactivity in the plume region.

Reaction of Al with ammonia by pulsed laser ablation: Optical analysis and mass spectrometry

Abstract In situ techniques have been employed to characterize laser plasma (plume) formation and reactions in the gas cloud formed from Al and NH 3 . Optical emission imaging and spectroscopy, and time of flight mass spectrometry have been used to monitor ablation plume components. AlN films have been synthesized by reaction of laser evaporated Al in a NH 3 atmosphere. Optical multichannel emission spectroscopy (OMA) and intensified charge coupled device (ICCD) imaging have been applied to identification of the deposition precursors occurring in the plasma.

Polycrystalline aluminum nitride films prepared by laser assisted Al and NH3 reaction

Abstract Aluminum nitride thin films have been fabricated by reaction of laser evaporated Al in a NH 3 atmosphere. The results indicate that AlN may deposit on a suitable substrate in a hexagonal crystal structure. A fairly dense homogeneous texture of the film surface morphology is seen by scanning electron microscopy (SEM). The main process parameters to produce layers of this material have been investigated.

Photoexcitation in thin films deposited on silicon substrates by reactive pulsed laser ablation

Reactive pulsed laser ablation is a very interesting method to deposit thin films of several materials and compounds such as oxides, nitrides, semiconductors and superconductors. This technique relies on photoablation of pure elements, or a mixture of materials, with simultaneous exposure to a reactive atmosphere. In the case of oxides, reactions between the laser vaporized metals and oxygen lead to the formation of intermediate complexes and finally to oxide thin films. The reactivity of the plume has been already studied by our group in other oxides and nitrides productions and ascertained by Time of Flight Mass Spectrometry measurements [1].

Pulsed laser deposition of pd on amorphous alumina substrate

Pulsed laser deposition is a growing technique used to prepare a wide variety of materials in thin film form. In this work experimental results of Pd coating on amorphous alumina substrate and the relation between the ablation process, the substrate characteristics and the quality of the deposits are described.

Epitaxial growth of thin films of SnSe semiconducting material

Pulsed laser ablation has been applied to thin films deposition from a tin selenide target. The growth of SnSe films has been analysed by electrical and optical techniques. The effect of laser fluence on the properties of the deposits has been also studied.