Nitrogen Partial Pressure Ratio Research Articles

Effect of N2/TMS Gas Ratio on Mechanical and Erosion Performances of Ti-Si-C-N Nanocomposite Coatings

To optimize the tribo-mechanical performance of thick Ti-Si-CN nanocomposite coatings for a wide range of harsh industrial applications, reactive gases of nitrogen and trimethylsilane were employed with specific flow rates of PEMS process. Plasma-enhanced magnetron sputtering (PEMS) was employed for depositing thick Ti-Si-C-N nanocomposite (22-27 µm) on Ti-6Al-4V substrates at relatively high deposition rate up to 4.5 µm/h. Controlling the nitrogen partial pressure ratio PN2/(PN2 + PTMS) from 0.29 to 0.69 resulted in controlling the chemical and physical properties of the coatings. The XRD results demonstrated that the crystallinity of the nanocomposite structure increased with the increase in nitrogen pressure ratio. The coating hardness, erosion resistance, sliding wear resistance and corrosion resistance were augmented with increasing the nitrogen content in the plasma atmosphere. The results displayed that the sliding wear resistance of Ti-Si-C-N coatings increased by approximately three orders of magnitude comparing with the uncoated Ti-6Al-4V substrate. At low nitrogen content, low coefficient of friction (0.13-0.15) was achieved. Furthermore, the coating prepared at high nitrogen content reflected greater values of ratios H/E* and H3/E*2 that correlated well with the coating erosion resistance.

Effects of Nitrogen Partial Pressure Ratio and Anneal Temperature on the Properties of Al–N Co-Doped ZnO Thin Films

The authors report the conversion of conduction type from n-type to p-type in the Al–N co-doped ZnO thin films by using thermal annealing treatment under argon atmosphere. The samples were deposited on fused silica by radio frequency magnetron sputtering. X-ray diffraction measurements showed that ZnO thin films have (002)-preferred orientation and the lattice constant decreases with the increase of nitrogen partial pressure. The average optical transmittance of these films is over 80%. The hole density is around 1.58 × 1017 cm−3 with an annealing temperature of 700°C. After exposing the samples in air for 1 year, the conduction type remains p-type with only a slight decrease of hole density, which indicates that the p-type ZnO with Al–N co-dopants has good electrical stability.

Preparation and characterization of CrN thin film by DC reactive magnetron sputtering

In this work, the DC reactive magnetron sputtering were used to deposit the chromium nitride (CrN) thin films on silicon (100) wafers and 304-type stainless steels in argon-nitrogen gas mixture at room temperature. The effect of nitrogen partial pressure ratios [%PN2 = PN2/(PN2+PAr)×100] on the microstructural were studied. The crystal structure of the prepared CrN films were analyst by X-ray diffraction. For the physical morphological analysis, atomic force microscopy and field-emission scanning electron microscopy were used. An element analysis of the CrN thin films were performed by energy dispersive X-ray spectroscopy (EDS). It was found that the deposition rate of the films increased with decreasing the nitrogen partial pressure ratio. The changes in crystal structures and morphological related with nitrogen partial pressure ratio were systematically investigated and discussed in this paper.

The effect of the terminating bonds on the electronic properties of sputtered carbon nitride thin films

Amorphous carbon nitride films (a-CN x) were grown by reactive radio-frequency magnetron sputtering of a graphite target in an argon/nitrogen gas mixture. The total discharge pressure was 1 Pa and the total nitrogen partial pressure (NPP) in plasma was varied between 0 and 100%. The correlation between the microstructure changes, the optoelectronic properties and the internal stress has been investigated in order to prevent the limiting role of the terminating bonds on the electronic properties of the a-CN x films, and to determine the range of the nitrogen content improving these properties. The analysis of the results reveals that below 3%, the nitrogen incorporation induces an increase in the density of π-bonds, which promotes the enhancement of the conductivity and the reduction of the optical gap. With increasing NPP ratio up to 6%, the formation of terminating bonds within the network reduces the connectivity of the graphitic network, decreasing the conductivity. For higher N content, the reaction of the bonds terminating with water can increase the compressive stress, leading to spontaneous delamination of films.

Structural and electrical properties of Ti-W-N thin films deposited by reactive RF sputtering

Ti-W-N thin films were deposited by reactive RF sputtering with a W-Ti(30 at.%) target in an argon/nitrogen atmosphere. The nitrogen partial pressure ratio in the growth chamber was varied from 0 to 11%. The influence of the nitrogen partial pressure ratio on the properties of Ti-W-N thin films was studied. The electrical resistivity of the Ti-W-N thin films varied gradually from 117.5μΩ•cm to 675μΩ•cm with the increase of nitrogen partial pressure ratio from 0 to 5.88%. However, the resistivity increased sharply if the ratio was raised further. X-ray photoelectron spectroscopy (XPS) analysis showed that nitrogen concentration in the films increased with the nitrogen partial pressure ratio and reached 36% when the ratio was 11%. Binding energy analysis showed that W was mainly in W2N and Ti was mainly in TiN when the film contained a nitrogen concentration of 36%. Grazing incidence X-ray diffraction (GIXRD) analysis confirmed that a f.c.c mixed phase W2N/TiN was present in the film. Moreover, the temperature coefficient of resistance and the micromachining of the Ti-W-N thin films were investigated.

Influence of disorder on localization and density of states in amorphous carbon nitride thin films systems rich in π-bonded carbon atoms

We discuss in this paper the evolution of both the density of states (DOS) located between the band-tail states and the DOS around the Fermi level N(EF) in amorphous carbon nitride films (a-CNx) as a function of the total nitrogen partial pressure ratio in the Ar/N2 plasma mixture. The films were deposited by three different deposition techniques and their microstructure was characterized using a combination of infrared and Raman spectroscopy and optical transmission experiments, completed with electrical conductivity measurements, as a function of temperature. The observed changes in the optoelectronic properties are attributed to the modification in the atomic bonding structures, which were induced by N incorporation, accompanied by an increase in the sp2 carbon bonding configurations and their relative disorder. The electrical conductivity variation was interpreted in terms of local effects on the nature and energy distribution of π and π∗ states.

Effect of growth ambient on the structure and properties of MgxZn1−xO thin films prepared by radio-frequency magnetron sputtering

MgxZn1−xO thin films were grown by the radio-frequency magnetron sputtering technique in Ar + N2 and O2 + N2 ambient with different nitrogen partial pressure ratios on quartz substrates at 773 K. The correlations between the growth ambient and the resultant films properties were discussed. It is found that Mg concentration, structure and band gap of the MgZnO film can be tuned by increasing the nitrogen partial pressure ratio of the Ar + N2 ambient, but cannot be tailored by changing the nitrogen partial pressure ratio of the O2 + N2 ambient. X-ray diffraction shows that the MgxZn1−xO films grown in the Ar + N2 ambient consist of wurtzite phase at the nitrogen partial pressure ratios from 0% to 50%, a mixture of wurtzite and cubic phases at the ratios of 78–83%, and a cubic phase at 100%, whereas such structure transformation did not exist in the MgxZn1−xO film deposited in the O2 + N2 ambient by changing the nitrogen partial pressure ratio. The Mg concentration increases linearly with the increasing nitrogen partial pressure ratio of Ar + N2, but does not vary with the increasing nitrogen partial pressure ratio of O2 + N2. The band gap increases linearly from 3.64 to 4.02 eV for the wurtzite MgxZn1−xO deposited in the Ar + N2 ambient as nitrogen partial pressure ratio increases from 0% to 50%, but the band gap of the MgxZn1−xO film deposited in the O2 + N2 ambient keeps a constant of 3.63 eV with oxygen gas and reaches 6.30 eV abruptly in pure nitrogen ambient (without oxygen gas). The MgxZn1−xO films, which are grown in the Ar + N2 and O2 + N2 ambient at nitrogen partial pressure ratio from 50% to 100% and 83% to 100%, respectively, show p-type conduction after annealing.

Nitrogen partial pressure-dependent Mg concentration, structure, and optical properties of MgxZn1−xO film grown by magnetron sputtering

MgxZn1−xO films were grown on quartz substrates at 773 K by using radio frequency magnetron sputtering with a mixture of argon and nitrogen as sputtering gases. The nitrogen concentration in the mixture is characterized by the nitrogen partial pressure ratio, which is determined by the ratio of nitrogen flow rate to the flow rates of nitrogen and argon. It was found that Mg concentration, structure, and band gap of the MgxZn1−xO film could be tuned by changing the nitrogen partial pressure ratio of the sputtering gases. The Mg concentration in the MgxZn1−xO film increases with increasing nitrogen partial pressure ratio. The MgxZn1−xO film consists of wurtzite phase at the ratios from 0% to 50%, mixture of wurtzite and cubic phases at the ratios between 50% and 83%, and cubic phase at 100%. The band gap of the MgxZn1−xO film with wurtzite and cubic structure increases as the ratio rises. The variation of the structure and band gap is attributed to change of the Mg concentration, which results from loss of the O and Zn atoms during growth process, the former is induced by reaction between N and O, and the latter by re-evaporation of Zn atoms due to high substrate temperature. The mechanism of the loss of the O and Zn atoms is discussed based on thermodynamics.

Control of structure, conduction behavior, and band gap of Zn1−xMgxO films by nitrogen partial pressure ratio of sputtering gases

Zn 1 − x Mg x O films were grown by radio-frequency reactive magnetron sputtering using mixture of nitrogen and argon as sputtering gases. It was found that Mg concentration, structures, electrical properties, and band gaps of the films can be tuned by changing nitrogen partial pressure ratio of the sputtering gases. The Zn1−xMgxO film consists of wurtzite phase at the ratios from 0% to 50%, mixture of wurtzite and cubic phases at the ratios of 78% to 83%, and cubic phase at 100%. The Mg concentration increased linearly with increasing the ratio. The band gap increases from 3.64eV at x=0.172to4.02eV at x=0.44 for the wurtzite Zn1−xMgxO and reaches 6.30eV for cubic Zn1−xMgxO with x=0.84. All the as-grown Zn1−xMgxO films show high resistivity at room temperature, but transform into p-type conduction after annealing at 600°C for 30min under 10−4Pa, except for the film grown at the ratio of zero.

Bias induced structural changes in tungsten nitride films deposited by unbalanced magnetron sputtering

Tungsten nitride thin films were deposited using unbalanced magnetron sputtering system. The effect of the ratio of nitrogen partial pressure to the total pressure during deposition and the substrate bias on the tungsten nitride formation has been studied. The glow discharge characteristics of the process have been studied in order to determine the deposition parameters. It is observed that nitrogen partial pressure ratio 0.4 and cathode current of 200 mA favors the formation of the W 2N films. The variation in the electrical resistivity of the films has been studied as a function of nitrogen partial pressure and substrates bias. A minimum resistivity of 406 μΩ cm is observed for tungsten nitride films prepared at −70 V bias. X-ray diffraction analysis of the films indicate the formation of β-W 2N (1 0 0) phase at the partial pressure ratio of 0.4. The effects of the bias on the structural properties were also studied at this condition. The internal stress and the particle size of the deposited films were calculated and it was found that there is no appreciable change with the applied bias voltage.

Composition and Structure Characterization of WNx Films Produced by RF Reactive Sputtering

AbstractWNx film is one of the most promising materials for self-aligned GaAs NASFET because of its low electrical resistivity and high Schottky Barrier Height at the WNx /GaAs contact.In this paper, the effect of the sputtering conditions and the annealing environment on the chemical composition and structure of the WNx films deposited on Si and GaAs by RF reactive sputtering are studied.The results show that with the increase of the partial pressure ratio of nitrogen gas or decrease of the working pressure, deposition rate of WNx film decreases, whereas the atomic percentage of N in the deposited film increases before approaching saturation. The WNx films formed at high working pressure (≈5 × 10−2 torr) consist of W, WN or W2N phases depending on the nitrogen partial pressure ratio. Whereas the films formed at low working pressure (≈ 3 × 10−3 torr) are usually amorphous. Annealing in a flowing N2 gas causes the crystallization of the amorphous films, which mainly consist of W+W2N. There is no change for the crystalline films. However, annealing in H2 gas causes severe loss of nitrogen of the film, the film becoming single W phase eventually.