Temperature coefficient of resistivity of TiAlN films deposited by radio frequency magnetron sputtering

Titanium aluminum nitride （TiAlN） film, as a possible substitute for the conventional tantalum nitride （TAN） or tantalum-aluminum （TaAl） heater resistor in inkjet printheads, was deposited on a Si（100） substrate at 400 ℃ by radio frequency （RF） magnetron co-sputtering using titanium nitride （TIN） and aluminum nitride （AlN） as ceramic targets. The temperature coefficient of resistivity （TCR） and oxidation resistance, which are the most important properties of a heat resistor, were studied depending on the plasma power density applied during sputtering. With the increasing plasma power density, the crystallinity, grain size and surface roughness of the applied film increased, resulting in less grain boundaries with large grains. The Ti, Al and N binding energies obtained from X-ray photoelectron spectroscopy analysis disclosed the nitrogen deficit in the TiAlN stoichiometry that makes the films more electrically resistive. The highest oxidation resistance and the lowest TCR of-765.43×10^-6 K-l were obtained by applying the highest plasma power density.

Fabrication of ZnO films by radio frequency magnetron sputtering and annealing

ZnO thin films were deposited on Si（111） substrates through a radio frequency （rf） magnetron sputtering system. Then the samples were annealed at different temperatures in air ambience and ammonia ambience respectively. The structure and composition of the ZnO films were studied by X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS）. The morphology of the samples was studied by scanning electron microscopy （SEM）. Measured results show that ZnO films with hexagonal wurtzite structure were grown on Si（111） substrates when annealed in the two ambiences. The volatilization process of ZnO in the ammonia ambience at high temperature was discussed and the mechanism of the reaction was analyzed.

Germanium nanoislands grown by radio frequency magnetron sputtering: Annealing time dependent surface morphology and photoluminescence

Structural and optical properties of ～ 20 nm Ge nanoislands grown on Si（100） by radio frequency （rI） magnetron sputtering under varying annealing conditions are reported. Rapid thermal annealing at a temperature of 600 ℃ for 30 s, 90 s, and 120 s are performed to examine the influence of annealing time on the surface morphology and photoluminescence properties. X-ray diffraction spectra reveal prominent Ge and GeO2 peaks highly sensitive to the annealing time. Atomic force microscope micrographs of the as-grown sample show pyramidal nanoislands with relatively high-density （～ 10^11 cm^-2）. The nanoislands become dome-shaped upon annealing through a coarsening process mediated by Oswald ripening. The room temperature photoluminescence peaks for both as-grown （～ 3.29 eV） and annealed （～ 3.19 eV） samples consist of high intensity and broad emission, attributed to the effect of quantum confinement. The red shift （～ 0.10 eV） of the emission peak is attributed to the change in the size of the Ge nanoislands caused by annealing. Our easy fabrication method may contribute to the development of Ge nanostructure-based optoelectronics.

Effect of Heat-treatment on Crystalline Phase and UV Absorption of 60CeO_2-40TiO_2 Thin Films by Magnetron Sputtering

60CeO2-40TiO2 thin films were deposited on soda-lime silicate glass substrates by R.F. magnetron sputtering. The effects of heat-treatment on the UV-absorption of the thin films were studied on the 60CeO2-40TiO2 thin film with the largest UV cut-off wavelength. The sample films with CeO2：TiO2=60：40 were heated at 773 K, 873 K, 973 K for 30 min. These films are characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and X-ray photoelectron spectroscopy and spectrometer （XPS）. XRD analysis proves that the addition of TiO2 to CeO2 changed the crystalline state of CeO2. But the UV absorption effect of CeO2-TiO2 films with CeO2 crystallite phase is inferior to that of the amorphous phase CeO2-TiO2 films. XPS analysis also indicates that the amorphous phase CeO2-TiO2 films have the most Ce3＋ content in these films. Amorphous phase and crystalline phase of the CeO2-TiO2 films have different effects on UV absorption of the thin films.

Preparation and Characterization of Nano-Particles PZT Ferroelectric Thin Films by RF-Magnetron Sputtering

Pt/Ti bottom electrodes were fabricated on SiO2/Si substrates by magnetron dual-facingtarget sputtering system. Lead zirconate titanate（PZT） thin films were deposited on Pt/Ti/SiO2/Si substrates by radio frequency （RF） magnetron sputtering system. The thickness of PZT thin films which were deposited for 5 h was about 800 nm. XRD spectra show that PZT thin films deposited in Ar ambience and rapid-thermal-annealed for 20 min at 700 ℃ have good crystallization behavior and perovskite structure. AFM micrographs show that mean diameter of crystallites is 70 nm and surface structures of PZT thin films are uniform and dense. Raw mean, root mean square roughness and mean roughness of PZT thin films are 34..357 rim, 2. 479 nm and 1. 954 nm respectively. As test frequency is 1 kHz, dielectric constant of PZT thin films is 327.5. Electric hysteresis loop shows that coercive field strength, residual polarization strength and spontaneous polarization strength of PZT thin films are 50 kV/cm, 10μC/cm^2 and 13μC/cm^2 respectively.

Effects of ratio of hydrogen flow on microstructure of hydrogenated microcrystalline silicon films deposited by magnetron sputtering at 100 ℃

Hydrogenated microcrystalline silicon(μc-Si:H)films were prepared on glass and silicon substrates by radio frequency magnetron sputtering at 100°C using a mixture of argon(Ar)and hydrogen(H2)gasses as precursor gas.The effects of the ratio of hydrogen flow(H2/(Ar+H2)%)on the microstructure were evaluated.Results show that the microstructure,bonding structure,and surface morphology of theμc-Si:H films can be tailored based on the ratio of hydrogen flow.An amorphous to crystalline phase transition occurred when the ratio of hydrogen flow increased up to 50%.The crystallinity increased and tended to stabilize with the increase in ratio of hydrogen flow from 40%to 70%.The surface roughness of thin films increased,and total hydrogen content decreased as the ratio of hydrogen flow increased.Allμc-Si:H films have a preferred(111)orientation,independent of the ratio of hydrogen flow.And theμc-Si:H films had a dense structure,which shows their excellent resistance to post-oxidation.

Fabrication of GaN films through reactive reconstruction of magnetron sputtered ZnO/Ga_2O_3

A simple and easily operated technique was developed to fabricate GaN films. GaN films possessing hexagonal wurtzite structure were fabricated on Si(111) substrates with ZnO buffer layers through nitriding Ga2O3 films in the tube quartz furnace. ZnO buffer layers and Ga3O3 films were deposited on Si substrates in turn by using radio frequency magnetron sputtering system before the nitriding process. The structure and composition of GaN films were studied by X-ray diffraction, selected area electron diffraction and Fourier transform infrared spectrophotometer. The morphologies of GaN films were studied by scanning electron microscopy. The results show that ZnO buffer layer improves the crystalline quality and the surface morphology of the films relative to the films grown directly on silicon substrates. The measurement result of room-temperature photoluminescence spectrum indicates that the photoluminescence peaks locate at 365 nm and 422 nm.

Tungsten Doped Indium Oxide Thin Films Deposited at Room Temperature by Radio Frequency Magnetron Sputtering

Tungsten doped indium oxide （IWO） thin films were deposited on glass substrate at room temperature by radio frequency reactive magnetron sputtering. Chemical states analysis was carried out, indicating that valence states of element W in the films were W4＋ and W6＋. The effects of sputtering power and film thickness on the surface morphology, optical and electrical properties of IWO thin films were investigated. The IWO thin films had high transmittance in near infrared （NIR） spectral range. The resistivity, carrier mobility and carrier concentration owned their respective optimum values as sputtering power and thickness changed. The asdeposited IWO film with the minimum resistivity of 3.23 × 10^-4 Ω cm was obtained at a sputtering power of 50 W, with carrier mobility of 27.1 cm2 V-1 s-1, carrier concentration of 7.15 × 10^20 cm-3, average transmittance about 80% in visible region and above 75% in NIR region. It may meet the application requirement of high conductivity and transparency in NIR wavelength region.

Study of magnetic and magneto-optical properties of heavily doped bismuth substitute yttrium iron garnet (Bi∶YIG) film

The magnetic and magneto-optical properties of heavily doped Bi∶YIG film were studied. The film was deposited by radio frequency magnetron sputtering method and crystallized by rapid recurrent thermal annealing (RRTA). The results show that the RRTA treated film has good properties both in microwave and optical wave band. The saturation magnetization of the film on different substrates varies from 135.7 to 138.6 kA·m-1. The coercive field of the film on GGG substrate is about 0.32 kA·m-1, while about 0.8-1.43 kA·m-1 on YAG substrate and 1.75 kA·m-1 on Al2O3 substrate. The Faraday angle is about 3-5 (°)·μm-1 when optical wavelength ranges at 450-600 nm. The transmission spectra of the Bi∶YIG films on three substrates has similar change as annealing temperature below 800 ℃. Specially, when annealing temperature is above 800 ℃ a step is observed between 550 and 650 nm wavelength for the film deposited on Al2O3 substrate.Three results are very useful in magneto-optical recording application and integrated microwave devices.

Effects of doping concentration on properties of Mn-doped ZnO thin films

This paper reports that the radio frequency magnetron sputtering is used to fabricate ZnO and Mn-doped ZnO thin films on glass substrates at 500 ℃. The Mn-doped ZnO thin films present wurtzite structure of ZnO and have a smoother surface, better conductivity but no ferromagnetism. The x-ray photoelectron spectroscopy results show that the binding energy of Mn2p3/2 increases with increasing Mn content slightly, and the state of Mn in the Mn-doped ZnO thin films is divalent. The chemisorbed oxygen in the Mn-doped ZnO thin films increases with increasing Mn doping concentration. The photoluminescence spectra of ZnO and Mmdoped ZnO thin films have a similar ultraviolet emission. The yellow green emissions of 4 wt.% and 10 wt.% Mn-doped thin films are quenched, whereas the yellow green emission occurs because of abundant oxygen vacancies in the Mn-doped ZnO thin films after 20 wt.% Mn doping. Compared with pure ZnO thin film, the bandgap of the Mn-doped ZnO thin films increases with increasing Mn content.

ITO Films Prepared by Long-throw Magnetron Sputtering without Oxygen Partial Pressure

This study has investigated the influence of the radio frequency （rf） power and working pressure on the properties of indium tin oxide （ITO） thin films, which were prepared by long-throw rf magnetron sputtering technique at room temperature. For 200 nm thick ITO films grown at room temperature in pure argon pressure of 0.27 Pa and sputtering power of 40 W, sheet resistance was 26.6 Ω/sq. and transmittance was higher than 88% （at wavelength 500 nm）. An X-ray diffraction analysis of the samples deposited at room temperature revealed a structural change from amorphous to mixed amorphous/polycrystalline structure at （222） and （400） texture with increasing rf power. The surface composition of ITO films was characterized by X-ray photoelectron spectroscopy （XPS）. Oxygen atoms in both amorphous and crystalline ITO structures were observed from O Is XPS spectra.

Preparation of TiO_2 Coated on Fabrics and Their Photocatalytic Reactivity

Nanoscale titanium dioxide functional films were prepared on the surface of the cotton woven fabric and the polyester knitted fabric at room temperature by Radio Frequency （RF） magnetron sputtering process. The surface microstructure and morphology were characterized by scanning electron microscope （SEM） and X-ray diffraction （XRD）. Photocatalytic property of two treated fabrics was tested in solar and ultraviolet （UV） radiation respectively, and their photocatalytic activity was compared. The results showed that the nanoscale titanium dioxide deposited on the surface of the treated fabrics was at different anastasia phase. The treated fabrics have excellent photocatalytic property, and after 30 launderings, the photocatalytic activity still maintained at a high level. Also, it indicated that the photocatalytic activity of the treated fabrics in UV radiation was higher than in solar radiation, but the effect wasn＇t very distinct. And at the same experimental magnetron sputtering parameters, the cotton coated with the nanoscale titanium dioxide showed better performance than the polyester fabric coated with the nanoscale titanium dioxide in terms of the photocatalytic property.

Preparation and characterization of GaN films grown on Ga-diffused Si (111) substrates

Hexagonal GaN films were prepared by nitriding Ga_2O_3 films with flowingammonia. Ga_2O_3 films were deposited on Ga-diffused Si (111) substrates by radio frequency (r.f.)magnetron sputtering. This paper have investigated the change of structural properties of GaN filmsnitrided in NH_3 atmosphere at the temperatures of 850, 900, and 950 deg C for 15 min and nitridedat the temperature of 900 deg C for 10, 15, and 20 min, respectively. X-ray diffraction (XRD),scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectronspectroscopy (XPS) were used to analyze the structure, surface morphology and composition ofsynthesized samples. The results reveal that the as-grown films are polycrystalline GaN withhexagonal wurtzite structure and GaN films with the highest crystal quality can be obtained whennitrided at 900 deg C for 15 min.

The influence of RF power on the electrical properties of sputtered amorphous InGa-Zn-O thin films and devices

The influence of radio frequency（RF） power on the properties of magnetron sputtered amorphous indium gallium zinc oxide（a-IGZO） thin films and the related thin-film transistor（TFT） devices is investigated comprehensively.A series of a-IGZO thin films prepared with magnetron sputtering at various RF powers are examined.The results prove that the deposition rate sensitively depends on RF power.In addition,the carrier concentration increases from 0.91 x 1019 to 2.15 x 1019 cm-3 with the RF power rising from 40 to 80 W,which may account for the corresponding decrease in the resistivity of the a-IGZO thin films.No evident impacts of RF power are observed on the surface roughness,crystalline nature and stoichiometry of the a-IGZO samples.On the other hand,optical transmittance is apparently influenced by RF power where the extracted optical band-gap value increases from 3.48 to 3.56 eV with RF power varying from 40 to 80 W,as is supposed to result from the carrierinduced band-filling effect.The rise in RF power can also affect the performance of a-IGZO TFTs,in particular by increasing the field-effect mobility clearly,which is assumed to be due to the alteration of the extended states in a-IGZO thin films.