Increasing Ar Pressure Research Articles

Stoichiometry control over a wide composition range of sputtered CuGaxIn(1−x)Se2

Films of CuGaxIn(1−x)Se2 (CGIS) have been grown by rf sputtering from stoichiometric single targets with different Ga/In ratios. Adjusting growth temperature and argon pressure we are able to deposit films with a wide range of Cu contents: From CGIS Cu-poor (16 at. %) to Cu2Se. Reevaporation of (Ga,In)2Se3 binaries is observed when substrate temperature is increased at a constant argon pressure (20 mTorr). An increase in Ar pressure from 5 to 150 mTorr at a growth temperature of 450 °C, produces a decrease in Cu atomic percentage from 24% to 16% due to a preferential diffusion of Cu sputtered atoms in the plasma. The relevant film properties of the analyzed films are found to be ruled by the Cu content. Graded composition absorbers with adequate physical properties for the fabrication of photovoltaic devices are grown with a proper choice of growth parameters.

Growth, Structure and Stress of DC Magnetron Sputtered TiB2 Thin Films

AbstractTiB2 is a very hard refractory compound that strongly resists erosion and shows metallic luster and good electrical conductivity. It has potential applications in protective coating systems. This paper investigates the microstructure and stresses of as-deposited TiB2 thin films ranging from 2000 °A to 4000 °A thick produced by dc magnetron sputtering as a function of sputtering power and Ar pressure. Three power levels: 100, 400, 600 W, and four pressures: 3, 5, 8, and 12 mTorr were used. X-ray diffraction studies indicate that two types of crystalline structure are formed: a randomly oriented fine crystalline structure and a coarser grained (001) textured structure, depending on the sputtering power and pressure. As-deposited stresses at different powers all show a transition from compression to tension as the Ar pressure increases. The relationship between the processing parameters, microstructure and residual stresses is discussed. The effects of the deposition power and pressure on the residual stress transition of TiB2 thin films are clearly mapped out by 3-D and contour maps.

Influence of Ar pressure on morphology and recording characteristics of hybrid sputtered magnetic disks

Hybrid sputtered magnetic disks of the type Cr/Co/sub 80/Ni/sub 20/ and Cr/Co/sub 62.5/Ni/sub 30/Cr/sub 7.5/ on Al/Ni-P substrates were prepared at Ar pressures of 5*10/sup -4/ to 5*10/sup -2/ mbar. From low to high Ar pressure, the morphology of the layer system changes drastically from a dense structure to a structure characterized by separated columns. The relative density of the metallic part of the layer decreases by 40 vol.% and the surface of the columns is oxidized by contact with air, creating a high O content of 20 at.% in the Cr layer and 6 at.% in the magnetic layer. As a consequence, the rectangular hysteresis loop, typical for longitudinally magnetized thin films, changes to a shape which is typical for pigmented media. Recording tests give constant values for resolution and D/sub 50/ (20-21.5 kfci). The signal level decreases by 50% with increasing Ar pressure, whereas the S/N ratio is drastically improved from 22 dB to 32 dB. The low S/N ratio of layers prepared at low Ar pressure is a consequence of strong exchange interaction between the closely packed magnetic crystallites, which creates high modulation noise. At high Ar pressure these interactions are blocked due to the columnar structure of the layer. >

Sputtered Tungsten Silicides Deposited at Different Argon Pressures

The argon impurities in sputtered tungsten silicide was measured in 2000Å thick films deposited by dc magnetron sputtering at Ar pressures ranging from 4 to 20 mtorr. The Ar concentration found by Rutherford backscattering spectrometry was in the film at 4 mtorr. The concentration decreased slowly with increasing Ar pressure and reaches at 20 mtorr. Target voltage changed from 555 to 455V with these Ar pressure changes. Si composition,, of changed from 2.46 to 2.61 and the stress of the films deposited on Si changed from with varying Ar pressure from 4 to 20 mtorr. The resistivity increased slowly with increasing Ar pressure, with an average value of 800 μΩ‐cm. These results indicate that the film properties are not much affected by Ar impurities contained in the film, especially after 1000°C annealing.

Effect of argon sputtering pressure on the magnetic properties and morphology of TbFeCo films

The effect of argon sputtering pressure on the magnetooptic and structural properties of TbFeCo amorphous films was investigated. The films were prepared by DC magnetron sputtering from a TbFeCo homogeneous alloy target. At low argon pressures, the Tb concentration in the film was lower than in the target, while at high pressures, the Tb concentration was greater in the film than in the target. The films deposited at low sputtering pressure have high Kerr rotation and reflectivity. The Kerr-hysteresis-loop squareness decreases and slantedness increases with increasing Ar pressure. The films prepared at low Ar pressure were very smooth and without detectable columnar growth. This supports the hypothesis that the columns are not required for the film to possess perpendicular anisotropy. The study indicates that it is possible to increase the performance and stability of the film by choosing appropriate deposition conditions.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Ar pressure dependence of saturation magnetization and film composition in TbCo and tbfe sputtered films

AbstractThe argon pressure dependence of saturation magnetization MS and film composition in TbCo and TbFe sputtered films under the substrate bias VB × 0 was investigated. It was found that the change in the shape of multitarget surfaces influences MS strongly. When the sputtering period was 60 min, the Ar pressure dependence of MS and the film composition were different in TbCo and TbFe films. This was found to be due to the existence of the composition gradient in the direction of the film thickness in the TbFe film deposited under high Ar pressure. As a result of investigating the multitarget surfaces, the Tb chip surface was found to be contaminated by TM atoms (Co, Fe) and the intermetallic compound was formed. On the other hand, the TM target surface was clean. The surface condition of the Tb chip was different in the Tb ‐ Co and Tb ‐ Fe multitargets. The Tb surface of the Tb ‐ Fe target was covered with cone‐shaped projections, causing the composition gradient in the film thickness direction when the Ar pressure was high. When the sputtering period was short (shorter than 12 min), the composition ratio against NTM/NTb) against MS and Tb decreases with the increase of Ar pressure in both depositions of TbCo and TbFe films.

Perturbation of line-intensities in the spectrum of HCl-rare gas mixtures

Individual line intensities were accurately measured in the O–2 transition of HCl perturbed by Argon. In particular, the intensity of the R O and P 1, line was shown to decrease with increasing Ar pressure. The rate of intensity variation was calculated by using some of the presently available potential surfaces for the HCl-Ar system. Satisfactory agreement with the experimental values was observed in most cases. Attempt was also made to extend the analysis to the HCl-Xe system.

Experiment and theory for CO2 laser-induced CF2HCl decomposition rate dependence on pressure and intensity

A laser-excited fluorescence method has been used to determine the rates at which CF2HCl molecules dissociate into CF2+HCl fragments during CO2 laser pulses of uniform fluence and known intensity. A study has been made of the dependence of the rate on CO2 laser intensity and pressure of Ar buffer gas from the collision-free regime to atmospheric pressure. The effect of increasing Ar pressure is initially to increase the CF2HCl dissociation rate; above a moderate pressure (∼50 Torr), the rate is independent of Ar pressure up to atmospheric pressure. The data has been compared to a model, which adequately reproduces all the experimental data. The model treats the effect of collision between CF2HCl and the argon buffer gas in terms of rotational equilibration or ’’hole filling’’ in the discrete energy level region of CF2HCl. The discrete energy levels are interfaced to a quasicontinuum of vibrational–rotational states in a self-consistent manner which incorporates a background of nonpumpable CF2HCl states as a finite heat bath interacting with the pump mode. The model is used to calculate the rate of formation of product CF2 molecules as a function of argon pressure and CO2 laser intensity. The quasicontinuum for CF2HCl is predicted to begin about four quanta above the ground state. The absorption cross section in the quasicontinuum is shown to decrease from 10−18 to 10−20 cm2 at V=15. The energy distribution in CF2HCl is predicted to be decidedly nonthermal both below and beyond threshold.