Fully dense, non-faceted 111-textured high power impulse magnetron sputtering TiN films grown in the absence of substrate heating and bias

We demonstrate the deposition of fully dense, stoichiometric TiN films on amorphous SiO₂ by reactive high power impulse magnetron sputtering (HiPIMS) in the absence of both substrate heating and applied bias. Contrary to the highly underdense layers obtained by reactive dc magnetron sputtering (dcMS) under similar conditions, the film nanostructure exhibits neither intra- nor intergrain porosity, exhibiting a strong 111 preferred orientation with flat surfaces. Competitive grain growth occurs only during the early stages of deposition (< 100 nm). The strong differences in the kinetically-limited nanostructural evolution for HiPIMS vs. dcMS are explained by high real-time deposition rates with long relaxation times, high ionization probabilities for Ti, and broad ion energy distributions.     

Grain growth and structural transformation in ZnS nanocrystalline thin films

Fabrication of ZnS thin films having similar stoichiometry at different substrate temperatures (T_S) e.g. 200 °C, 300 °C and 400 °C by means of RF magnetron sputtering method is presented. The films grown at T_S of 200 °C are in cubic zinc-blende phase and textured along (111) plane. The films deposited at T_S of 300 °C and 400 °C are in hexagonal wurtzite phase. The surface roughness and grain size of the films increase with increasing T_S. The ultra-violet and visible absorption studies show that the bandgap of films can be tailored by varying T_S, taking advantage of the structural transformation.     

Heteroepitaxy of Ir films on silicon with a ceria/yttria stabilized zirconia buffer layer

Heteroepitaxial Ir films on Si(001) with a double ceria/yttria stabilized zirconia heteroepitaxial buffer layer were grown by magnetron sputtering. As-deposited CeO₂ films covered with {111} faceted pyramids resulted in iridium films with the [001] axis normal to the substrate plane. The buffered substrates annealed at 1115 °C have a smooth surface; Ir films on such substrates have the (111) orientation and consist of grains turned at 90° toward each other.     

In-situ electrical characterization of ultrathin TiN films grown by reactive dc magnetron sputtering on SiO2

Ultrathin TiN films were grown by reactive dc magnetron sputtering on thermally oxidized Si (100) substrates. The electrical resistance of the films was monitored in-situ during growth in order to determine the minimum thickness of a continuous film. The coalescence thickness has a minimum of 1 nm at a growth temperature of 400 °C after which it increases with growth temperature. The minimum thickness of a continuous film decreases with increasing growth temperature from 2.9 nm at room temperature to 2.2 nm at 650 °C. In-situ resistivity measurements show that films grown at 500 °C and above are resistant to oxidation indicating high density. X-ray photoelectron spectroscopy and X-ray diffraction measurements show that the TiN grain stoichiometry and grain size increases with increasing growth temperature.     

Effects of deposition parameters on tantalum films deposited by direct current magnetron sputtering

Effects of deposition parameters on tantalum films deposited by direct current magnetron sputtering were studied. The results indicated that the electrical properties were relative to the oxygen and other impurities rather than to growth orientation. As the sputtering power increases from 25 to 100 W, the preferred-growth orientation of Ta films changes from (200) to (202) and the oxygen and impurities content in the films decrease. The temperature coefficient of resistance also reduces from −289.79 to −116.65 ppm/°C. The O/Ta ratio decrease and grain size reduction related to a change of electrical resistivity were observed at substrate temperatures in the range 300-500 °C. At 650 °C, partial stable α-Ta associated with a sharp decrease of the electrical resistivity was also found.     

制备条件对电致变色氧化镍薄膜特性的影响

在充氧气的真空室内 ,用电子束蒸发NiO粉末颗粒的方法分别以 0 1和 0 8nm/s的淀积速率制备了氧化镍薄膜 ,并在不同的环境中对薄膜进行热处理。研究了薄膜结构和电致变色特性与淀积速率的关系 ,发现以较慢和较快速率淀积的薄膜分别具有NiO晶粒的 (2 0 0 )和 (111)不同择优取向 ,前者致色范围较小 ,后者致色范围较大。还研究了热处理对薄膜的结构、动态致色范围、致色效率 ,以及红外光谱特性的影响 ,发现热处理对薄膜的致色效率影响较小 ,然而对动态致色范围的影响很大。     

Growth of niobium oxide films on single-crystal silicon

200-nm-thick niobium films grown on single-crystal silicon wafers by magnetron sputtering have been oxidized by annealing in flowing oxygen. X-ray diffraction examination revealed the metal-like phase Nb₆O in the as-deposited films. Annealing in flowing oxygen for 1 h led to the formation of tetragonal NbO₂ at 570 K and hexagonal Nb₂O₅ at temperatures above 770 K. The grain size and surface roughness of the films were evaluated using atomic force microscopy.     

Optical and structural properties of vanadium pentoxide films prepared by d.c. reactive magnetron sputtering

Vanadium pentoxide films were deposited onto glass substrates at different substrate temperatures (RT—400 °C) by d.c. reactive magnetron sputtering. The structural properties of the films were studied by X-ray diffraction, scanning electron microscopy and Raman spectra. The optical properties of the films were studied by measuring and fitting the transmittance. The film prepared at low temperature showed a high optical transmittance. The film prepared at the substrate temperature lower than 200 °C has an amorphous structure and the film prepared at substrate temperatures higher than 200 °C had a polycrystalline V₂O₅ structure. The optical parameters of the films were calculated by fitting the transmittance using the classical model.     

Reactive DC Magnetron Sputtering Deposition of Copper Nitride Thin Film

Copper nitride thin film was deposited on glass substrates by reactive DC （direct current） magnetron sputtering at a 0.5 Pa N2 partial pressure and different substrate temperatures. The as-prepared film, characterized with X-Ray diffraction, atomic force microscopy, and X-ray photoelectron spectroscopy measurements, showed a composed structure of Cu3N crystallites with anti-ReO3 structure and a slight oxidation of the resulted film.The crystal structure and growth rate of Cu3N films were affected strongly by substrate temperature. The preferred crystalline orientation of Cu3N films were （111） and （200） at RT, 100℃. These peaks decayed at 200℃ and 300℃ only Cu （111） peak was noticed. Growth of Cu3N films at 100℃ is the optimum substrate temperature for producing high-quality （111） Cu3N films. The deposition rate of Cu3N films estimated to be in range of 18-30 nm/min increased while the resistivity and the microhardness of Cu3N films decreased when the temperature of glass substrate increased.     

Role of the crystallinity of ZnO films in the electrical properties of bottom-gate thin film transistors

The strong correlation between the microstructural characteristics of ZnO channel layers grown at various temperatures by radio-frequency magnetron sputtering and the electrical performances of resulting bottom-gate thin film transistors (TFTs) was reported. Transmission electron microscopy revealed that increasing growth temperature enhanced degree of c-axis preferred orientation and enlarged width of columns in the ZnO films. The ZnO channel layers grown at 250 and 350 °C exhibited TFT saturation behavior. However, growing them at ≥ 350 °C produced small grains in the junctions of ZnO/SiO₂ interface and grain boundaries, which led to hump behavior in TFT transfer curve caused by formation of additional boundaries.     

Deposition of nickel oxide by direct current reactive sputtering: Effect of oxygen partial pressure

Nickel oxide thin films were deposited by Direct Current magnetron reactive sputtering from Ni target onto SnO₂:F conductive glass substrates. The process was carried out without intentional heating, in an argon/oxygen gas mixture with various oxygen contents and discharge currents. The polycrystalline NiO thin films were deposited with controlled growth of the structure along [111] and [200] crystallographic directions for chosen conditions. Morphology of as-deposited films was found to depend on the preferentially oriented NiO crystals. Moreover, on the basis of discharge voltage as a function of the O₂ partial pressure for a constant discharge current, we present here the method to estimate the deposition conditions allowing us to achieve the desired preferential growth of transparent p-type semiconductor NiO, by Direct Current magnetron reactive sputtering.     

Growth behavior and optical properties of N-doped Cu2O films

N-doped Cu₂O films are deposited by sputtering a CuO target in the mixture of Ar and N₂. The structures zand optical properties have been studied for the films deposited at different temperatures. It is found that N-doping can suppress the formation of CuO phase in the films. The films are highly (100) textured at low temperatures and gradually change to be highly (111) textured at the temperature of 500 °C. With the analysis of (111) and (100) grain sizes, the surface free energy and grain size of critical nuclei are suggested to dominate the film texture. The analysis of the atomic force microscopy shows that the film growth can be attributed to the surface-diffusion-dominated growth. The forbidden rule of band gap transition is found disabled in the N-doped Cu₂O films, which can be attributed to the occupation of 2p electrons of nitrogen at the top of valence band. The optical band gap energy is determined to be 2.52 ± 0.03 eV for the films deposited at different temperatures.     

Structural and electrical properties of RuO2 thin films prepared by rf-magnetron sputtering and annealing at different temperatures

Conductive ruthenium oxide (RuO₂) thin films have been deposited at different substrate temperatures on various substrates by radio-frequency (rf) magnetron sputtering and were later annealed at different temperatures. The thickness of the films ranges from 50 to 700 nm. Films deposited at higher temperatures show larger grain size (about 140 nm) with (200) preferred orientation. Films deposited at lower substrate temperature have smaller grains (about 55 nm) with (110) preferred orientation. The electrical resistivity decreases slightly with increasing film thickness but is more influenced by the deposition and annealing temperature. Maximum resistivity is 861 μΩ cm, observed for films deposited at room temperature on glass substrates. Minimum resistivity is 40 μΩ cm observed for a thin film (50 nm) deposited at 540°C on a quartz substrate. Micro-Raman investigations indicate that strain-free well-crystallized thin films are deposited on oxidized Si substrates.     

The effects of substrate temperature on the structure and properties of ZnO films prepared by pulsed laser deposition

ZnO thin films were prepared by pulsed laser deposition (PLD) on glass substrates with growth temperature from room temperature (RT) to 500 °C. The effects of substrate temperature on the structural and optical properties of ZnO films have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission spectra, and RT photoluminescence (PL) measurements. The results showed that crystalline and (0 0 2)-oriented ZnO films were obtained at all substrate temperatures. As the substrate temperature increased from RT to 500 °C, the ratio of grain size in height direction to that in the lateral direction gradually decreased. The same grain size in two directions was obtained at 200 °C, and the size was smallest in all samples, which may result in maximum E_g and E₀ of the films. UV emission was observed only in the films grown at 200 °C, which is probably because the stoichiometry of ZnO films was improved at a suitable substrate temperature. It was suggested that the UV emission might be related to the stoichiometry in the ZnO film rather than the grain size of the thin film.     

Influence of deposition temperature on the structure and optical properties of HfO2 thin films

Hafnium oxide (HfO₂) thin films were deposited on Si (001) substrates by electron beam evaporation at various growth temperatures. It was found that the film was amorphous when deposited at temperatures lower than 200°C. It was polycrystalline when deposited at 250°C and 300°C. At temperatures above 400°C, it was grown preferably along the [111] direction. The influence of growth temperature on the surface morphology and optical property was also investigated.     

The effects of substrates on the thin-film structures of BaTiO3

Barium titanate (BaTiO₃) thin films prepared on magnesia, silicon and strontium titanate substrates by r.f. sputtering has been investigated. As a function of substrate and annealing temperatures, the crystal structure and shape were examined by X-ray diffraction and scanning electron microscopy. Thin films were grown on both MgO and silicon substrates; they were amorphous when deposited on MgO if the substrate temperature was less than 450 °C, while for those grown on silicon the temperature had to be less than 500 °C. Above these elevated temperatures, the films were crystalline, with cubic symmetry. After annealing the thin films on magnesia, the crystal structure changed from cubic to tetragonal phase above 1100 °C; thebe c-axis or annealing thus caused the grain growth of the BaTiO₃. The thin films on SrTiO₃ were found toc-axis oriented tetragonal films for a substrate temperature above 500 °C.     

Epitaxial growth of solution grown polyvinylchloride (PVC) films

Thin films of polyvinylchloride (PVC) have been grown epitaxially from three different solvents onto the (001) plane of rocksalt crystals by the isothermal immersion technique. The ranges of values of the growth parameters (temperature and concentration of the solution and immersion time) over which epitaxial growth is obtained have been established in each case. Films grown from a benzene and acetone mixture show epitaxy only at temperatures of 58°C or more and with concentrations below 0.1 g/100 ml. The epitaxial relation is (010) [110]_PVC∥(001) [110]_NaCl. The crystallites in the epitaxial films are of pyramidal shape and the molecular chains are folded in a direction perpendicular to the substrate. Films grown from ethyl methyl ketone solution show epitaxy only at temperatures of 65°C or more for concentrations greater than or equal to 0.15 g/100 ml. Films grown from cyclohexanone solution show epitaxy over a wide range of temperatures and concentrations. The epitaxial relation is (001) [110]_PVC∥(001) [110]_NaCl and the crystallites are rod- or fibre-like. The molecular chains in these crystallites are folded in a direction parallel to the substrate. Our studies show that epitaxial growth occurs in the earliest stage of growth of the films and further growth results in a mixture of amorphous and polycrystalline regions. The mechanism of epitaxial growth is explained in terms of our model for the growth of polymer chains. Two possible configurations of the molecular chains in the unit cell of PVC on a (001) rocksalt surface are proposed to explain the two epitaxial orientation relations observed.     

Effects of substrate temperature on the microstructure and photocatalytic reactivity of TiO2 films

Transmission electronic microscopy is used to study the structure, morphology and orientation of thin TiO2 films prepared by reactive magnetron sputtering on glass slides at different substrate temperatures (100 to 400 °C). The TiO2 films are used to purify a dye in waste water. The microstructure and photocatalytic reactivity of TiO2 films have been shown to be functions of deposition temperature. In the temperature range examined, all film samples have a porous nanostructure and the dimension of particles grown with increasing deposition temperature. Films are amorphous at temperatures of 100 °C and only anatase phase forms at 200 °C and above. Films deposited between 200 to 300 °C show a preferred orientation, while films at 400 °C change into complete random orientation. Deposition at 250 °C yields high efficiency in photocatalytic degradation owing to the high degree of preferred orientation and nanocrystalline/nanoporous anatase phase. © 1998 Kluwer Academic Publishers     

Novel properties of AZO film sputtered in Ar+H2 ambient at high temperature

AZO (ZnO:Al) transparent conductive thin film was prepared by RF magnetron sputtering with a AZO (98 wt% ZnO 2 wt% Al₂O₃) ceramic target in the same Ar+H₂ ambient at different substrate temperatures ranging from 100 to 300 °C. The minimum resistivity of AZO films was 7.9×10⁻⁴ Ω cm at the substrate temperature of 200 °C. The average transmission in the visible rang was more than 90%. Scanning electron microscopy and XRD analyses showed that the surface morphology of the AZO samples altered with the increasing of the substrate temperature. AZO film prepared at 200 °C in the pure Ar ambient was also made as comparison about the resistivity, carrier concentration and the average crystallite size. The resistivity became about 3 times higher. The carrier concentration became lower and the average crystallite size was smaller.     

On the structure and surface chemical composition of indium-tin oxide films prepared by long-throw magnetron sputtering

Structures and surface chemical composition of indium tin oxide (ITO) thin films prepared by long-throw radio-frequency magnetron sputtering technique have been investigated. The ITO films were deposited on glass substrates using a 20 cm target-to-substrate distance in a pure argon sputtering environment. X-ray diffraction results showed that an increase in substrate temperature resulted in ITO structure evolution from amorphous to polycrystalline. Field-emission scanning electron microscopy micrographs suggested that the ITO films were free of bombardment of energetic particles since the microstructures of the films exhibited a smaller grain size and no sub-grain boundary could be observed. The surface composition of the ITO films was characterized by X-ray photoelectron spectroscopy (XPS). Oxygen atoms in both amorphous and crystalline ITO structures were observed from O 1 s XPS spectra. However, the peak of the oxygen atoms in amorphous ITO phase could only be found in samples prepared at low substrate temperatures. Its relative peak area decreased drastically when substrate temperatures were larger than 200 °C. In addition, a composition analysis from the XPS results revealed that the films deposited at low substrate temperatures contained high concentration of oxygen at the film surfaces. The oxygen-rich surfaces can be attributed to hydrolysis reactions of indium oxides, especially when large amount of the amorphous ITO were developed near the film surfaces.