Rozprawy doktorskie na temat „Ni-Cr Thin Films”

Electrical transport in undoped and Ni-, Cr-, and W-doped TiO2 thin films on SrTiO3(001) is modelled either with the sum of two thermally activated processes with exponential temperature dependence of conductivity, or with the sum of three-dimensional Mott variable-range hopping (VRH) and an activated process with low activation energy. The latter is interpreted for both models as small polaron hopping (<θD/4). According to reduced chi-square values, the double activated model is superior for data of higher ordered films grown at 540 and 460 °C. For lower growth temperature, VRH plus activated conductivity fits partly better. For all dopants, n-type conductivity is observed.

Магістерська дисертація: 81 сторінка, 41 рисунків, 12 таблиць, 38 літературних джерел. Об’єкт досліджень:структурно-фазові перетворення в наношарових композиціях Cu/Cr, Ni/Cr, Ni/Cu/Cr за умов вакуумного термічного відпалу та з додатковою йонно-плазмовою обробкою. Мета роботи: дослідження особливостей впливу попередньої йонно-плазмової обробки на структурно-фазові перетворення у тонких плівках Cu/Cr, Ni/Cr, Ni/Cu/Crза умов термічного відпалу. Методи дослідження: мас-спектрометрія вторинних йонів, трансмісійна електронна мікроскопія, in-situ високоенергетична електронна дифракція. Досліджено особливості формування структури та фазового складу систем Cu/Cr, Ni/Cr та Ni/Cu/Cr при відпалі у вакуумі у широкому температурному інтервалі. Тонкоплівкові композиції були одержані шляхом термічного випаровування у вакуумі і, в подальшому, піддавалися йонно-плазмовій та термічній обробці до температур 690 °C. Після обробки плівки досліджено методами мас-спектрометрії вторинних йонів, трансмісійною електронною мікроскопією, in-situ високоенергетичною електронною дифракцією. Зафіксовано розвиток окисно-відновних процесів, які ефективно контролюються шляхом використання додаткового плазмового оброблення плівок. Йонний низькоенергетичний вплив стабілізує структуру досліджуваних систем шляхом гальмування процесів рекристалізації.
Master thesis: 81 pages, 41 figure, 12 tables, 38 references. The object of research is structural-phase transformations in nanolayer compositions Cu/Cr, Ni/Cr, Ni/Cu/Cr under conditions of vacuum thermal annealing and with additional ion-plasma action. The purpose is to study the peculiarities of the influence of preliminary ion plasma action on structural-phase transformations in thin films Cu/Cr, Ni/Cr, Ni/Cu/Cr under conditions of thermal annealing. Research methods: secondary-ion mass spectrometry, transmission electron microscopy, in-situ high-energy electron diffraction. The peculiarities of the formation of the structure and phase composition of the Cu/Cr, Ni/Cr and Ni/Cu/Cr systems during annealing in vacuum in a wide temperature range have been studied. The thin film compositions were obtained by thermal evaporation in vacuum and subsequently subjected to ion-plasma and heat treatment to temperatures of 690 °C. After processing the film, it was investigated by secondary-ion mass spectrometry, transmission electron microscopy, in-situ high-energy electron diffraction. The development of redox processes, which are effectively controlled by the use of additional plasma treatment of films, has been recorded. Ionic low-energy effect stabilizes the structure of the studied systems by inhibiting recrystallization processes.

碩士
中國文化大學
材料科學與奈米科技研究所
96
Two high-entropy CrFeCoNiCuAl0.5 and CrFeCoNiCuAl1.0 alloy targets were prepared by arc-melting and vacuum induction melting processes. The thin films deposited on the oxidative Si substrates by PVD process, followed by heat treatment at different conditions. The microstructures and compositions of these thin films were analyzed by SEM with EDS, and the resistivity was measured by a four-point probe. Results indicated that the average thickness of the CrFeCoNiCuAl0.5 and CrFeCoNiCuAl1.0 were 0.87 and 0.92μm, respectively. All of these as-deposited thin films had a columnar structure, but these columnar structures would transform to fine granular structures after annealing. The resistivity of these thin films increased with increasing the annealing temperatures and annealing times, but the resistivity of these thin films decreased at initial stage of vacuum annealing because the defects would vanish during high-temperature annealing. Furthermore, the oxidation resistive of CrFeCoNiCuAl0.5 was better than that of CrFeCoNiCuAl1.0 film during high annealing. In addition, no very low resistivity (superconductivity) was observed in present study.

Aero engines are one of the most complex machines on this planet and have propelled the necessity of advanced material technologies. Health monitoring of the engine is performed by a variety of sensors and amongst these strain sensor is very important as it aids in evaluating the stresses experienced by the body. Unlike conventional foil gauge which tends to debond under hostile environments in the engine like high rpm of blades, temperature, mass flow, etc, thin film based strain gauges are likely to exhibit better adhesion on the substrates. The usage of Ni-Cr thin films in strain gauge sensor has been proven for static application, wherein the substrate does not experience the fluctuating loads. Material and mechanical aspects of thin films for design and development of thin film based strain gauge sensor for aero engine application was taken up as a research work. One of the objectives of the work was to characterize the Ni-Cr thin films with varying composition deposited by sputter deposition process and characterize the films for its microstructural features and mechanical properties. The correlation of these properties is performed and amongst the film compositions investigated the film with alloy composition of Ni-Cr:80-20 at% exhibits the most distinct columnar structure, highest electrical resistivity (2.037 μΩm), hardness (5.8 GPa) and the modulus (180 GPa). This Ni-Cr: 80-20 at% film exhibits no surface cracks when loaded in the elastic region of the titanium alloy GTM-Ti-64. Resistance to deformation under the action of externally applied load on a body results in stress within the body. In single or multilayer film stacking the stress experienced in the film by virtue of substrate deformation needs to be investigated quantitatively. The substrate stresses are transferred to the films by shear stresses at the interface. In order to measure the surface strain by change in the electrical resistance of the gage it is important to quantitatively evaluate the stresses in the films. Are these stresses very high to cause delamination and film cracking or are these stresses too less to be measured. In order to understand the stress evolution and transfer mechanism, an analytical approach, numerical simulation and experimental validation were performed. Thin film strain gauge device architecture has been engineered such that an insulating layer of alumina is deposited on substrate and a sensing layer is deposited on the insulating layer to avoid thermal mismatch and maintain the strain compatibility. A alumina of 45 micron thick alumina layer was successfully deposited on Titanium alloy (GTM-Ti-64) by sputter deposition without any edge delamination and microcracks. Finite Element Analysis (FEA) results showed that the axial and shear stress profiles at the Ti alloy-alumina interfaces for both single and multilayer architecture are similar and higher when compared with the stresses in alumina-NiCr. The shear stress profile for single layer and multilayer architecture follows the modified shear lag model with peak shear stresses at the extremes and peak axial stress at the centre of the film. The axial stresses in the alumina film is found to be significant in both FEA and validated by experimental findings with film fracture strength of 814 MPa. Similarly, the shear stresses were found to be minimal by FEA studies and the experimental finding suggests the film fracture under tensile mode. Complete strain transfer was observed from substrate to these thin films under both tensile and vibratory fatigue, suggesting proper adhesion of the alumina film on the Ti alloy substrate. The maximum strain compatibility of thin film alumina on Ti alloy substrate was found to be 0.22 %. A Goodman correction for the fatigue data under axial mode was performed and on combining the entire fatigue data for R = -1 linear fit was observed across all the data points wherein the Basquin equation was considered for data analysis and the fatigue strength coefficient and exponent are found to be 872.56 and -0.054 for alumina thin film on Ti alloy substrate. Thin film strain gauges (TFSG) with these characteristics were deposited on the compressor rotor blade of one of the typical aero engines. Thick contact pads and a new bonding technique are used for taking the lead wires. The entire multilayer structure with wire bonding was tested under static and dynamic (vibratory fatigue) conditions and TFSG exhibited a reproducible strain when compared against foil based strain gauge under both tension and compression. TFSG device was tested for a duration of 2200 seconds with a blade vibration frequency of 406 Hz i.e. 8.9x105 cycles. During the entire test duration, TFSG successfully measured strains from the aero engine blade.

碩士
義守大學
材料科學與工程學系
92
Abstract The purpose of this experiment is to investigate the effects of Cr concentration to the Ni-Cr alloy, and to find the influence of sputtering parameters to deposition rate, phase identify, optical properties of thin film by fabricating Ni-Cr thin film with DC sputtering method. The change of sputtering parameters is the different sputtering power(500W, 750W, 1000W), and working pressure(3mtorr, 5mtorr, 8mtorr, 10mtorr). In the results of alloy, the twin structure can be observed from microstructure of scanning electron microscopy in the alloy with low Cr concentration, the alloy with high Cr concentration has some precipitates in the microstructure, but there is not much affected for the distribution of precipitate to properties of thin film. The density in the center of alloy is a little higher than it at the edge by measuring, they have the same phase form X-Ray diffraction, and there is no shifting of diffraction peak. Above these results, we can know that the alloy has a fine uniform and it is good for thin film properties. In the results of thin film, the deposition rate decreased fewer with the increasing of Cr concentration, but the deposition rate of pure Ni film is not at the maximum point because of the long sputtering working distance in pure Ni film. It can be observed that thin film and alloy have the same crystalline of phase from phase identify with the method of Grazing Incident X-Ray Diffraction (GID), and the diffraction peak are shifting to the low angle with the increasing of Cr concentration, it means that the amount of Cr concentration can be solutted more into the Ni phase. In the part of optical properties; the reflectance of short wave length increase, and the reflectance of long wave length decrease with the increasing of Cr concentration because Cr has a good reflectance for short wave length, Ni has a good reflectance for long wave length, moreover the reflectance of long wave length and it of short wave length are getting to close with the increasing of Cr concentration, so the image will not be confused for using the pure Cr to the reflection mirror. For the deposition rate; it increase obviously with the increasing of sputtering power, and has a fine crystalline, there is a little affected of deposition rate to the thin film reflectance. In this experiment, it can be observed that the deposition rate doesn’t has a turning point to the working pressure, and it has a little effect to the crystalline, the deposition rate to the reflectance is decreasing obviously because the range of the sputtering working pressure is not extensive.

碩士
輔仁大學
物理學系
89
The mainly purpose of this thesis is sputtering nickel, titanium and Ni-Ti thin films on substrate, and then uses x-ray diffractometer, and spectrophotometer Cary-5E to measure its optical properties. Also we use spectrophotometer Cary-5E to measure the optical spectrum of the Co-Cr thin films. At first, we use x-ray diffractometer to measure Ti’s components. Then use spectrophotometer Cary-5E to measure the optical spectrum for the nickel, titanium, Ni-Ti and Co-Cr thin films of different thickness to compare their transmittance, reflectance, and absorptance. We find the optical spectrum shake with increasingly thickness of Ni-Ti, and Ti thin film. The distance with peak appear and again is about 1000Å. And then I make my sample with 1000Å, 2000Å,3000Å,4000Å, and 5000Å.For example by the transmittance in 652nm wavelength of Ni and Ni79Ti21 (1000Å),the transmittance intensity of Ni thin film is 45.4% with smooth line, but the transmittance intensity of Ni79Ti21 thin film is 72.5%，and it is the first peak. Now we know the phenomenon of Ni-Ti thin film is the peak, and the transmittance getting more increase with increasingly Ti. For the base components of Co-Cr, they have the same quality of transmittance. The quality of transmittance is lower in long wavelength，and it decrease gradually by increasingly thickness.

博士
國立中山大學
電機工程學系研究所
104
With the demand of electronic devices increasing for information and telecommunication technologies, the passive component with high precision and high reliability properties have become more important in the recent years. The main process of thin film resistor is by sputtering technology to perform high precision of resistance, lower temperature coefficient of resistance (TCR) and high reliability properties. The thin film resistors are widely used in electronic circuit. Among the thin film resistor processes, the laser trimming dominate the precision of resistance and TCR is dominated by composition of sputtering target, sputtering condition and annealing condition. In this study, we focus on the dependence of TCR on different Ni-Cr film thickness and different annealing conditions. The electron mean free path (MFP) and scattering mechanisms of carriers due to surface scattering, grain boundary scattering and surface roughness scattering of Ni-Cr film have been determinate. The experimental results show the electron MFP is about 24.2nm. The TCR performance is increasing with annealing temperature increasing obviously for the thickness of Ni-Cr film is less than electron MFP. The TCR performance is stable as the Ni-Cr film thickness is thicker than the electron MFP, and decreases slightly as the annealing temperature increases. This is because the film is discontinuous with island structure which scattering of electrons at imperfections is dependent on temperature and the TCR increasing. For the thickness of Ni-Cr film is thicker than electron MFP, the film is continuous structure. There is a Cr2O3 oxidation layer on the surface of thicker Ni-Cr film after annealing process. An interdiffusion reaction phenomenon is occurrence. The Cr is diffused out to form Cr2O3 layer and caused higher Ni concentration in inside conductive layer. Thus the TCR decreased with the increase in annealing temperature. Finally, the electrical conduction mechanisms of Ni-Cr thin film resistor are demonstrated by different film thickness through scattering models fitting. The resistivity and temperature coefficient of the resistance of Ni-Cr thin film are measured to investigate the influence of thickness with different annealing temperature. An oxidation and atom inter-diffusion model was proposed to explain the effects of film thickness on the electrical properties of Ni-Cr thin film resistor under different annealing temperature. As the result, we obtained the thin film resistors of low TCR under ±5 ppm/0C at -55 0C and 125 0C.

碩士
義守大學
材料科學與工程學系碩士班
93
The objective of this experiment is to make a series study of the electric resistance and microstructure of Ni-Cr thin film. Ni-Cr thin film is made by DC sputtering with different power(500W,750W,1000W) and pressure(3,5,8,10mtorr). The effects of Cr content, sputtering parameters, and temperature on the film characteristic and electric resistance are investigated. Finally, try to find the relationship between the electric resistance and the microstructure. According to the results, some of the relations can be confirmed in the Ni-Cr thin film system. The deposition rate decreased with the increasing Cr content, because the sputtering yield of pure Ni is higher than Cr. The deposition rate increased linearly with increasing power, but there is no obvious variation with increasing pressure. The electric resistance of thin film decreased substantially with increasing film thickness, and it stabilized when the film thickness above 1500Å. The relation between film resistance and film thickness will not be changed by different Cr content, sputtering parameters, and temperature. The ability which film resistivity against to the variable temperature will change at the different film thickness, according to the thickness, it can be divided into three parts. In the same way, the relation of TCR and temperature also can be divided into three parts. By the way of integrating the above-mentioned, and to compare it with TEM, the process of formation in the thin film can be established. For the MC thin film, at the film thickness which is from 50Å to 200Å, it is a short-range-order and it is not as the form as Ni-Cr thin film. When the film thickness is form 200 Å to 2000 Å, it has already been at the second stage, and the film thickness is above 2000 Å, it is getting into the final stage. For the HC thin film, it is as same as MC at 50~200 Å, and the second stage is 200~1000 Å ,after 1000 Å , it will be at the third stage. With the increasing Cr content, TCR will decrease when Cr>44wt%, but it will increase at Cr60wt%. The best TCR will be at the Ni56wt%-Cr44%, 750W, 3mtorr, and film thickness is 900 Å.

碩士
義守大學
材料科學與工程學系碩士班
95
This experiment mainly is changes the heat treatment conditions to discuss the resistance of the nichrome thin film. The nichrome thin film was made by DC sputter at a pressure of 3mtorr at an DC power of 500, 750 and 1000W respectively. This experiment focused on electronic resistance of N8C2 and N5C4 thin film and to discuss relationship of microstructure. Demonstrated by the experimental result in, N8C2 thin film temperature increasing with sheet resistance and electronic resistivity. However number of heat treatment increase, the electronic resistivity of thin film is tend to stable. Compare to N5C4, itself microstructure is differ from N8C2, although along with the temperature increase, the thin film sheet resistance and electronic resistivity increase. But increasing number of heat treatment, its does not have the obvious change. According to above both results, the resistance of N5C4 thin film is better than N8C2 thin film. But N8C2 also use reheat to improve the thin film stability. Then discussing constant heat treatment, constant heating time is 30, 60 and 90 minutes respectively. The more constant heating time, the higher resistance of thin film. But resistance of thin film would increasing at 90 minutes. Although increasing constant heating time, the electronic resistivity of thin film also slightly decreased for N5C4. However its electronic resistivity is stable than N8C2. Therefore from above discussing, along with holds the constant heating time to be effectively improve the electronic resistivity of thin film, it also stabilize the thin film regardless influence of temperature.

碩士
國立臺灣大學
機械工程學研究所
94
In this study, Ti-6Al-4V and 17-4PH stainless steel (S.S.) are joined by infrared vacuum brazing using three different filler alloys. Those filler alloys are BAg-8, Ag-Cu-1.75Ti, and Ti-20Zr-20Cu-20Ni (wt%). Prior to infrared brazing, thin films of Cr/Ni (10μm/1μm) or Cr (10μm) are coated on the 17-4PH S.S. as diffusion barriers. The aim of introducing the diffusion barrier(s) is to prevent interdiffusion between two dissimilar alloys from forming intermetallics, so better bonding strength can be expected. Experimental results show that the best shear strength can be obtained from the Cr/Ni film coated on 17-4PH S.S. By SEM observation of crack propagation in shear-tested specimens, for both Cr/Ni and Cr surface coatings on 17-4PH S.S., they are mostly fractured at Ti-Cu intermetallics. The former ones have thinner Ti-Cu intermetallics layer, so that the crack can easier extend to the Ag-rich phase, which is tougher than the Ti-Cu phase. Dynamic wetting angle test of Ti-20Zr-20Cu-20Ni on different substrates shows that Ti-6Al-4V is completely wetted, and Cr/Ni surface coating on 17-4PH S.S. has better wettability than bald on 17-4PH S.S. By the shear test and SEM observation for the joints of Ti-6Al-4V/Ti-20Zr-20Cu-20Ni/17-4PH S.S., the bonding strength is quite low due to the formation of Ti-Fe intermetallics, even if there is Cr/Ni thin film coated on 17-4PH S.S. as a diffusion barrier.

碩士
中國文化大學
材料科學與製造研究所
91
This thesis is according to the concept of equal-more multi alloys (high entropy alloys) by Dr.Ye that he is a professor in material science department of Tsing Hua University . Using this concept to compound the element of Cr, Fe, Co, Ni, Cu, Al into CrFeCoNiCuAlx alloys. The x in this formula is 0.5, 1.0, 2.0, and take those alloys to experiment corrosion. The result shows when the three alloys immerse in HCl50% and H2SO450﹪, their anti-corrosion is better than 304 stainless steel in market, but the anti-corrosion immersed in HNO350﹪and Marble’s etching solution is less than 304 stainless steel. The better anti-corrosion of four acids of those alloys is CrFeCoNiCuAl0.5, this is because six phases high entropy alloy is one phase(FCC) structure and its segregation is small. Taking this alloy to fabricate it into target and deposit it on substrate. Further, we take it thin film sputtering and analysis of its property. The result shows that (a) increasing the sputter’s power or argon’ flow rate, it can improve the rate of thin film deposition. (b) because the substrate doesn’t use the cooling setup, with sputter’s time increasing and increasing the average grain size of thin film. (c) increasing the sputter’s time will form the roughness of thin surface increasing, and when annealing the thin film will reduce the surface’s roughness and resistance (d) the reduce modulus of this thin film is 220 15Gpa and its hardness is reducing when time is increasing. In best condition of sputtering is 100W 60S.C.C.M and take it 90 minutes, the hardness of thin film is 8 Gpa that is four times than bulk.

碩士
國立屏東科技大學
機械工程系所
104
In this experiment is prepared quinary alloy Ni-Cr-Mn-Y-Nb、Ni-Cr-Mn-Y-Dy、Ni-Cr-Mn-Y-Cu、Ni-Cr-Mn-Y-Tb thin films on glass and Al2O3 substrates by DC and RF magnetron co-sputtering. The influence of composition, phase structures, microstructures and electrical properties of Ni-Cr-Mn-Y-X thin films under different elements addition and annealing temperatures were investigated. When the annealing temperatures setting up 350 °C, the Ni-Cr-Mn-Y-Nb thin films with an amorphous structure was observed by X-ray diffraction (XRD). However the Ni17Y12 and Nb2O5 peaks were observed at 500 °C. The resistivity of Ni-Cr-Mn-Y-Nb films was increased with increasing of Nb addition amount and annealing temperatures. The Ni-Cr-Mn-Y-Nb films with 14.3 at.% Nb addition amount and annealed at 350 °C which was exhibited the best electrical properties with a resistivity of 633 μΩ – cm and a temperature coefficient of resistance (TCR) value of 2.5 ppm/°C. When the annealing temperatures setting up 300 °C, the amorphous structure was observed in the Ni-Cr-Mn-Y-Dy thin films by XRD and transmission electron microscopy (TEM). The resistivity of Ni-Cr-Mn-Y-Dy films was increased with increasing of Dy addition amount and the TCR value becomes convergence and close to zero. The Ni-Cr-Mn-Y-Dy films with 32.2 at.% Dy addition amount and annealed at 300 °C which was exhibited the higher resistivity 1590 μΩ – cm with -6.2 ppm/°C of TCR. In the Ni-Cr-Mn-Y-Cu thin films, Y2Cu2O5 crystallization phase were observed after annealing at 300 °C. The TCR value significantly increases with increasing Cu addition amount. When the Cu added at 14.3 at.% and annealed at 350 °C which was exhibited the highest resistivity ~ 795 μΩ – cm. When the annealing temperature was set to 350 °C, the Ni-Cr-Mn-Y-Tb films was observed Tb2O3 phase by TEM selected-area electron diffraction (SAED). When the annealing temperature increase to 400 °C, the thin films crystallized into Ni17Y12 and Tb2O3 phase by XRD detecting. The resistivity of Ni-Cr-Mn-Y-Tb films increases obviously with increasing of Tb addition amount. When the Tb added at 32.5 at.% and annealed at 350 °C which was exhibited the highest resistivity ~ 1877 μΩ-cm. The TCR values were decreased with increasing of Tb addition amount. The Ni-Cr-Mn-Y-Tb films with 25.1 at.% Tb amount and annealed at 300 °C which was exhibited the best TCR -4.5 ppm/°C with 1259 μΩ-cm of resistivity.

碩士
國立高雄應用科技大學
機械與精密工程研究所
101
In this study, aluminum nitride and nickel-chromium-silicon- aluminum thin films are prepared using DC magnetron sputtering deposition, respectively. To obtain different compositions of AlN thin film, the sputtering conditions are adjusted such as sputtering power, concentration of nitrogen ratio and annealing temperature. The effects of sputtering parameters on the phase transformation, microstructure and mechanical property, and electrical property of AlN and Ni-Cr-Si-Al thin films are investigated. The results show that as-deposited films with amorphous structure are observed using X-ray diffraction analysis. When 500 W sputtering power is applied to prepare AlN thin films, the AlN peaks are appeared at 500 ℃ annealing. The AlN crystalline is enhanced in thin films at 600 ℃ annealing. In addition, pure AlN phase with hexagonal can be obtained at 500 ℃ annealing when the sputtering power is enhanced from 500 W to 800 W. In mechanical analysis, the micro-hardness is increased from 32 Hv (500 W) to 70 Hv (800 W), and the scratch width is decrease from 90 μm (500 W) to 15μm (800 W). Based on the optimum processes of AlN thin films, the Ni-Cr-Si-Al thin films are deposited on AlN thin film/Al2O3 substrates. The effects of Ar/N2 ratio, sputtering power and annealing temperature of AlN thin film on the electrical properties of Ni-Cr-Si-Al thin films are investigated. The results showed that the resistivity of Ni-Cr-Si-Al thin films with AlN film as middle layer is 9962 μΩ-cm with -205 ppm/℃TCR after 360 ℃/4 h annealing. However, the resistivity of Ni-Cr-Si-Al thin films without AlN film as middle layer is 10789 μΩ-cm with -180 ppm/℃TCR after 360 ℃/4 h annealing.