Metallic Alloy Target Research Articles

Femtosecond pulsed laser ablation of metal alloy and semiconductor targets

The properties of metal alloy (CoPt and inconel) and semiconductor (GaAs and InP) nanoclusters formed via femtosecond laser pulses were investigated. Ablation of the target materials was carried out both in vacuum (10−4Pa) and at set pressures in a number of background gases. The results of this work indicate that short laser pulses (low picoseconds/femtoseconds) alone are not enough to guarantee the production of films with stoichiometries matching those of the target materials. The production of stoichiometric alloy films depends on the similarity of the vapor pressures of the target constituents, while the production of stoichiometric compound films requires ablation in the presence of a background gas and compound constituents of comparable mass.

Optical investigations in a PEM controlled reactive magnetron sputter process for aluminium doped zinc oxide layers using metallic alloy targets

The use of aluminium doped zinc oxide (ZAO) as transparent conductive layer (TCO) has growing importance especially for production of solar modules. A significant cost reduction of TCO thin film production is expected by use of much less expensive metallic alloy targets. ZAO films with good TCO properties can be achieved only in the transition mode of the reactive sputter process. To stabilize the discharge for long stretched magnetron sputter sources on the working point needed a process control system is required. The intensity of zinc emission lines is used as control parameter. The control is performed by adding varying amounts of oxygen gas to the discharge region using the Plasma Emission Monitor PEM ®05. This allows a combination of reproducible TCO film properties with stable high deposition rates. By use of an optical emission spectrometer AOS-4 it was investigated in situ, which emission lines are best suited for the process control. Herefore the chronogram mode of the spectrometer is used, which allows spectral lines to be monitored with a time resolution of a few milliseconds. Furthermore, other spectral line intensities are investigated for use as regulation parameter. A concept for regulating a reactive sputter process by use of several emission lines is discussed. The concept was applied for DC discharge and MF discharge as well. A time-resolved investigation of the interesting spectral lines in MF discharge is carried out with microsecond resolution.

Deposition of TCO films by reactive magnetron sputtering from metallic Zn:Al alloy targets

The use of aluminum doped zinc oxide (ZAO) as transparent conductive oxide(TCO) has gained importance with the beginning of Cu(In,Ga)Se 2 (CIGS)-based thin-film module production. Commonly these layers are deposited from ceramic ZAO targets. However, a high cost reduction is expected if it is possible to use much less expensive metallic alloy targets. A comparison of the results of applying different reactive sputtering techniques is presented. Plasma emission monitoring (PEM) is needed to control the process. A multichannel PEM system is used to obtain homogeneity over long target lengths. A comparison between sputtering from Zn:Al targets and pure Zn targets aids to understand specifics of the sputtering process. Samples deposited by the different techniques are characterized by resistivity and transmittance measurements. It is shown that ZAO films deposited from metallic targets show comparable properties compared with films deposited from ceramic targets. As a first result of applying this reactive sputtering technique with metallic targets, module efficiencies exceeding 10% could be realized on 30×30 cm 2 CIGS modules.

A Study on the Deposition of ITO Films at Low Temperature by Inclination Opposite Target Type DC Magnetron Sputtering Method

In the present study, the ITO films were produced onto plastic film substrate at room temperature by the inclination opposite target type DC magnetron sputtering equipment, in which a metallic indium tin alloy target was used. The effects of oxygen flow rate and bias voltage on the electric resistivity and transparency of the ITO films were discussed. For low electric resifitivity of the ITO films, the electromagnetic shielding effectiveness was studied. The results obtained were as follows: (1) The ITO films produced at room temperature has very smooth surface. (2) The electric resistivity of ITO films deposited at room temperature showed minimum value at the oxygen flow 0.4 sccm. (3) The electric resistivity of ITO films deposited at room temperature depended on the bias voltage and showed the minimum value in the bias voltage of -70V. (4) When the optimum coating conditions were selected, the electric resistivity of 3.l2 × l0-4Ω·cm was obtained. (5) When the bias voltage was -70V, the ITO films deposited at room temperature showed the most electromagnetic shielding effectiveness.

Figure of Merit for Deposition Conditions in ITO Films

Indium tin oxide (ITO) films were deposited on unheated PET substrates by DC reactive magnetron sputtering of In-Sn (90-10 wt%) metallic alloy target. Electrical and optical properties of as-deposited films were systematically studied by control of the deposition parameters such as working pressure, DC power, and oxygen partial pressure. The figures of merit are important factors that summarize briefly the relationship between electrical and optical properties of transparent conducting films. The formulae of T/Rsh/ and T10// Rsh/ are expressed as a function of transmittance and sheet resistance. The best values of those figures of merit were approximately 38.6 and 8.95 (10-3/Ω-1/), respectively.Ā᐀會Ā᐀뢦ﾖ⨀ᢘ墵Ā저會Ā저Ⴇﾖ⨀나墵Ā㰀會Ā㰀梧ﾖ⨀備墵ĀḀ會ĀḀ삧ﾖ⨀끿쾯ĀḀ會ĀḀᢨﾖ⨀ꁯ᪢ԀĀ᐀會Ā᐀炨ﾖ⨀㡰᪢܀܀좨ﾖ⨀ᣚ쒟ĀĀĀ會ĀĀ₩ﾖ⨀䀱⒤ĀĀĀ會ĀĀ碩ﾖ⨀耗㮛ĀĀĀ會ĀĀ킩ﾖ⨀ࡶ펗ĀĀĀ會ĀĀ⢪ﾖ⨀灲躙ԀĀ᐀會Ā᐀肪ﾖ⨀遨鶘ЀĀ᐀會Ā᐀�ﾖ⨀惝ĀĀĀ會ĀĀカﾖ⨀ĀĀĀ會ĀĀ被ﾖ⨀傀쾯Ā會Āﾖ⨀瀄ᆠĀ搀會Ā搀㢬ﾖ⨀ᒣĀ저會Ā저邬ﾖ⨀硣ᒣĀ

Reactive magnetron sputtering of tin-doped indium oxide (ITO): influence of argon pressure and plasma excitation mode

Tin-doped indium oxide (ITO) films have been prepared by reactive magnetron sputtering from a metallic alloy target onto unheated substrates. In a systematic study, the influence of the working pressure and the discharge mode (DC, pulsed DC or RF) on the electrical and structural properties of ITO films was investigated. It was found that the RF excitation (13.56 MHz) of a magnetron discharge is the most effective one with respect to the usage of the oxygen for oxidising the sputtered metal atoms on the substrate surface. When varying the working pressure (0.3–3.4 Pa), the oxygen partial pressure for the resistivity minimum of the ITO films is independent of the working pressure for RF excitation. Exciting the plasma by DC, an increasing oxygen amount is necessary in order to prepare low resistant ITO films when increasing the working pressures. This behaviour can be explained by different sources for the input of energetic particles into the growing film for RF and DC excitation. In a DC discharge, most of the energetic particles stem from the target surface (e.g. reflected neutral argon atoms or negative oxygen ions), while in a RF magnetron discharge, the largest part of the energetic particles has its origin in the plasma in front of the substrate. By Rutherford backscattering analysis the chemical composition of the ITO films as a function of the oxygen partial pressure was investigated. Fully oxidised ITO films exhibit an oxygen excess of approximately 15%. Low resistant ITO films show an oxygen-to-metal ratio of approximately 1.5, suggesting a film structure where the tin atoms occupy indium lattice sites. From the XRD analysis, a compressive strain in the ITO films of up to 2% was measured, which seems to be caused by the excess oxygen in the films. Furthermore, the ITO films exhibit a density which is up to 20% lower than that of bulk indium oxide.

Mechanisms for O2 dissociation during pulsed-laser ablation and deposition

We investigate different dissociation mechanisms for O2 gas during pulsed-laser ablation and deposition. Mesaurements are carried out by using an in situ diagnostics based on absorption spectroscopy of oxygen gas, with space- and time-resolved capabilities, during laser ablation of a metal alloy target in the presence of an oxygen environment. Data, analyzed as a function of ablation parameters, indicate that two different mechanisms, involving electron collisions and formation of a high-density, high-temperature shock layer, play an important role in producing atomic oxygen which can subsequently react with the ablated species.

ZrO 2–CeO 2 and CeO 2–La 2O 3 film growth on oxide substrates and their applications in oxide heterostructures

The pulsed laser deposition of several cerium-based oxides has been studied in order to prepare buffer layers tailored to the epitaxial growth of oxides. It has been shown that ceria-based oxide films with a sufficiently wide variation of lattice constant (0.541–0.551 nm) could be prepared. CeO 2, Zr 1− X Ce X O 2 and Ce 1− X La X O 2− X/2 epitaxial films with low roughness were obtained. The results obtained by RHEED, XRD, RBS and AFM methods have confirmed the high quality of heteroepitaxial CeO 2, Zr 1− X Ce X O 2 and Ce 1− X La X O 2− X/2 layers, and we have evaluated the difference in crystallinities for the films grown from metallic alloy targets and sintered oxide targets. These films can be used in YBa 2Cu 3O 7-based heterostructures as insulating barriers. In the case of Ce 1− X La X O 2− X/2 (0⩽ x⩽0.4) high-quality epitaxial films are obtained on LaAlO 3 and SrTiO 3, the buffer layers are epitaxially grown with a 45° rotation of the in-plane axes with respect to those of the substrate and the surface roughness is low ( R rms=0.24 nm/1 μm 2). The properties of YBa 2Cu 3O 7 films deposited on these buffered substrates are as good as those for the film grown without any buffer layer, and furthermore the field dependence of the R's at 77 K and 10 GHz is better, being about 3.8×10 −3 mΩ/Oe which is smaller than the 9×10 −3 mΩ/Oe recorded in the case of unbuffered substrates.

Heteroepitaxial growth of ZrO2−CeO2thin films on Si (001) substrates

We have studied Zr1−XCeXO2 film growth on (001) Si by Pulsed Laser Deposition using sputtering of metallic alloy targets and sintered ceramic targets. The conditions of the epitaxial growth have been found and optimized. The epitaxial oxide film growth (001) [100]||(001) [100] Si was obtained for a range of CeO2 content in ZrO2: from 4.5 up to 14% mol in ZrO2. The oxide film structure corresponds to a tetragonal phase with strong preference for c-axis orientation normal to the growth surface. The results obtained by RHEED, XRD and AFM methods have confirmed the high quality of heteroepitaxial Zr1−XCeXO2 layers, and the difference in crystallinities for the films grown from metallic alloy targets and ceramic targets was evaluated. The XRD results show the absence of any reflection distinct from (00l) and (l00) for films grown from alloy targets, and, in contrast with this, the film structure contains some random oriented inclusions in the case of oxide target deposition. Use of metallic alloy Zr-12% Ce targets and low oxygen pressure during deposition provide the best film quality with the minimum of surface microrelief (Rrms < 0.3 nm for 1 × 1 µm2 surface area was achieved).

Chemical instability of the target surface during DC-magnetron sputtering of ITO-coatings

Indium–tin oxide (ITO) coatings on polymer film substrates should have the required properties already in their as-deposited state and should be chemically and thermally stable. The coatings can be produced either by reactive DC-magnetron sputtering of In/Sn (e.g., 80/20, wt.%) metallic alloy targets or by pseudo-reactive sputtering of ITO (In 2O 3SnO 2 90/10, wt.%) targets. In the former process (and to a lesser extent in the latter process), a surface instability of the target arises: black crystals of a dark phase grow on the target surface, changing the target voltage and causing pronounced arcing in the plasma. This harmful phenomenon grows worse during a sputter run and finally necessitates abortion of the run and mechanical cleaning of the target. This phenomenon has never been explained in literature. In this paper, it will be shown that the black crystals are In 2O and that they originate from an equilibrium reaction at the target surface in which In 2O 3 is decomposed into In 2O and O 2. This reaction is especially annoying with reactive processes in which optical plasma emission monitoring (PEM) is used as a control means to obtain the correct stoichiometry of the coatings at relatively high sputter deposition rates.

Single-wall carbon nanotube formation by laser ablation using double-targets of carbon and metal

During laser ablation to form single-wall carbon nanotubes, the composition at the surface of a target composed of C, Ni and Co became metal-rich and the yield of single-wall carbon nanotubes decreased. This problem was solved by applying double-target laser ablation where separate carbon and metal-alloy targets were simultaneously irradiated by the laser light.

Ozone in reactive gas for producing tin-doped indium oxide films by DC reactive magnetron sputtering

We propose ozone (O 3) as a reactive gas for producing tin-doped indium oxide (ITO) films by DC reactive magnetron sputtering using a metallic alloy target for the first time. We show that incorporation of O 3 enhanced the reaction with the sputtered metal atoms on the substrate surface at room temperature due to its powerful oxidizing nature. The effect of O 3 in oxygen (O 2) gas on the properties of the ITO films was investigated. It is found that high transparency and low resistivity film can be fabricated at high deposition rates and low substrate temperatures by using ozone in oxygen gas.

Study of annealed indium tin oxide films prepared by rf reactive magnetron sputtering

Tin doped indium oxide (ITO) films were deposited on glass substrates by rf reactive magnetron sputtering using a metallic alloy target (In-Sn, 90-10). The post-deposition annealing has been done for ITO films in air and the effect of annealing temperature on the electrical, optical and structural properties of ITO films was studied. It has been found that the increase of the annealing temperature will improve the film electrical properties. The resistivity of as deposited film is about 1.3 × 10 −1 gW ∗ cm and decreases down to 6.9 × 10 −3 Ω ∗ cm as the annealing temperature is increased up to 500 °C. In addition, the annealing will also increase the film surface roughness which can improve the efficiency of amorphous silicon solar cells by increasing the amount of light trapping.

Study of annealed Indium Tin Oxide Films Prepared by RF Reactive Magnetron Sputtering

AbstractTin doped indium oxide (ITO) films were deposited on glass substrates by rf reactive magnetron sputtering using a metallic alloy target (In-Sn, 90-10). the post-deposition annealing has been done for ITO films in air and the effect of annealing temperature on the electrical, optical and structural properties of ITO films was studied. It has been found that the increase of the annealing temperature will improve the film electrical properties. the resistivity of as-deposited film is about 1.3 х 10-1 Ω*cm and decreases down to 6.9 х 10-3Ω*cm as the annealing temperature is increased up to 500 °C. IN addition, the annealing will also increase the film surface roughness which can improve the efficiency of amorphous silicon solar cells by increasing the amount of light trapping.

SnInO-based chlorine gas sensor

The dependence of the resistance of InSnO (ITO) layers on a small amount of chlorine gas in air is studied here. The chlorine-sensitive ITO films have been fabricated by reactive sputtering of In and Sn from a metal alloy target (In and Sn in the proportion 0.94:0.06 by weight) on silicon substrates. It is found that the chlorine gas in the ambient atmosphere makes the ITO resistance increase. The dependence of the resistance on chlorine concentration tends to saturate at concentrations above 3 ppm. The sensitivity maximum is observed at 300 °C. The addition of Pt significantly increases the sensitivity and reduces the temperature of the sensitivity maximum. The response time is ≈ 150 s at 90 °C and decreases exponentially with increasing temperature. The results obtained are typical for gas sensors based on tin oxide or ITO and can be explained in terms of electron localization at surface adsorption centres dominated by chlorine molecules and the electric transport features at the polycrystalline film grain boundaries.

Band gap narrowing and the band structure of tin-doped indium oxide films

Films of tin-doped In 2O 3 were prepared by r.f. reactive sputtering using a metallic alloy target (InSn, 80-20). The annealing of films in different ambients of N 2, O 2 and cracked ammonia as well as different thicknesses of the films yielded carrier densities in the range 1×10 20 to 1×10 21 cm −3. The reflectance and transmittance were measured in the energy range 1.38–4.14 eV. The band gap was found to increase with increasing carrier density. The present data, along with the reported results for indium tin oxide (ITO) films, have been analysed by taking into consideration the band gap narrowing due to electron-electron and electron-impurity scatterings within the random phase approximation. Addition of band gap narrowing at different carrier densities to the measured band gaps at respective concentrations reported by different workers, when equated to the Burstein-Moss widening, shows that the intrinsic band gap of the films depends on the preparation conditions. Almost all the reported data of ITO films can be fitted to an average-reduced effective mass m vc ∗=0.22 m e . The band structure of ITO can be represented by a parabolic band with the conduction band curving upwards and the valence band downwards rather than the previously reported structure where both bands curve upwards.

Deposition of tin-doped indium oxide films by a modified reactive magnetron sputtering process

It has been difficult to deposit high quality indium tin oxide (ITO) films onto large area polymeric substrates that cannot be heated (over 40–50 °C) during deposition or subjected to post-deposition annealing. We have developed a modified process based on reactive magnetron sputtering of a metallic indium tin alloy target to deposit good quality ITO films with deposition rates as high as 4Å s -1 at a target-substrate distance of 10 in. Films with sheet resistance less than 10 Ω/□ and integrated visible transmission greater than 85% have been deposited using this process onto 12 in 12 × 12 in polymeric substrates at ambient temperature. A detailed description of the above process with an emphasis on obtaining control over the properties and reproducibility of good quality ITO films using this technique is presented in this paper.

Preparation of the alloy target for magneto-optical recording media

A novel method of preparing rare-earth-transition metal (RE-TM) alloy targets suitable for use as magnetooptical media is developed. Three different targets are studied. One contains only alloy powders made by simultaneous reduction of and diffusion reactions between RE-oxide and TM powders (target A). The others contain alloy powders combined with both RE powders (target B) and alloy powders combined with both RE and TM powders (target C). Radial distributions of the film compositions on the disks are observed. Compositional variance of sputtered films prepared by targets that underwent long usage is also monitored. The compositional uniformity in the radial direction is superior for targets B and C. Target A, which has the lowest permeability among the three, exhibits better aging behaviour. >

Magnetron sputtering and laser patterning of high transition temperature Cu oxide films

High Tc Y-Ba-Cu-O films have been prepared by dc magnetron sputtering of metal alloy targets. To circumvent the negative ion effect, two alloy targets, YCu and BaCu, are sputtered in an argon atmosphere with an oxygen spray near the substrate. Films deposited on sapphire with onsets at 92 K and a 6° transition width (10–90%) have been achieved using this technique. These films have been successfully patterned with the technique of laser ablation.

Rf reactive sputtering of indium-tin-oxide films

Films of indium-tin-oxide (ITO) have been deposited by rf reactive diode sputtering of metallic InSn alloy targets, or ceramic ITO targets, in an Ar and Ar + O2 atmosphere. Electrical as well as optical properties of ITO films were controlled by varying sputtering parameters and by post-deposition heat-treatment in Ar, H2, N2, H2 + N2 ambients. The ITO films exhibited low resistivity ∼2 × 10−4 Ω cm, high transmittance ∼90% in the visible spectral region and high reflectance ∼80% in the near infra-red region.