首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Multiferroic BiFe0.95Co0.05O3 thin films were fabricated on Pt/Ti/SiO2/Si substrates at various temperatures by pulsed laser deposition. It was found the deposition temperature had great effects on phase purity, orientation, microstructure and multiferroic properties of these films. The optimized deposition temperature was close to 600?°C. Polarization–electric field (P–E) and magnetization–magnetic field (M–H) hysteresis loops at room temperature were observed simultaneously in the films fabricated at 600?°C. The remnant polarization, coercive electric field (P r , E c ) and the remnant magnetization, coercive magnetic field (M r , H c ) of the films deposited at 600?°C were (0.95?μC/cm2, 31?kV/cm) and (0.59?emu/cm3, 130 Oe), respectively. These results might have implications for further investigations on high quality BiFe0.95Co0.05O3 multiferroic films.  相似文献   

2.
The influence of substrate temperature and the silane-to-nitrogen ratio on the structure of silicon films 0.5–0.6 μm thick deposited onto amorphous SiO2 substrates was investigated by X-ray diffraction. The investigations were carried out for silicon films deposited at various temperatures in the range 500–750 °C and with various silane-to-nitrogen ratios in the range 3.04 × 10-4-2.84 × 10-3 by volume. The silicon films deposited at 500 °C were amorphous while the films deposited at 550 °C were randomly oriented polycrystalline. The films deposited in the temperature range 600–700 °C were polycrystalline with a preferred orientation that changed from 〈110〉 through 〈100〉 to 〈111〉. The structure of the films deposited at 750 °C was randomly oriented polycrystalline. Investigations of the influence of the silane-to-nitrogen ratio on the silicon film structure revealed that the structure of films deposited at a substrate temperature of 500 °C was independent of the silane-to-nitrogen ratio. The structure of the films deposited at 600 °C depended on the silane-to-nitrogen ratio and changed from polycrystalline with a 〈110〉 preferred orientation to randomly oriented polycrystalline when the ratio was increased. The structure of films deposited at 700 °C also depended on the silane-to-nitrogen ratio and changed from randomly oriented polycrystalline to polycrystalline with double preferred orientation (〈100〉 and 〈111〉) when the ratio was increased.  相似文献   

3.
Transparent hexagonal BN films were deposited onto copper substrates from the reactant gas BCl3-NH3-H2 at temperatures in the range 250–700°C. The lowest deposition temperature of the films was about 250°C. The films deposited at temperatures below 450°C were unstable in moist atmosphere and devitrified; a 20%–30% decrease in weight was observed when these films were heated above 600°C in an argon atmosphere. In contrast, the films deposited at temperatures above 600°C were very stable, decreased in weight by 1%–2% on heating and were stable in air at temperatures below 750°C.  相似文献   

4.
Thin films of Ga2O3:Mn have been deposited on silicon (100) substrates without intentional heating by radio frequency (RF) planar magnetron sputtering from a Mn-doped Ga2O3 target in an oxygen-argon mixture atmosphere. Microstructure and properties of the deposited Ga2O3:Mn films were systematically investigated as a function of the post-deposition annealing temperature in the range between 500 °C and 1200 °C. X-ray diffraction (XRD) measurements showed that the as-deposited Ga2O3:Mn films were of an amorphous structure in nature. The Ga2O3:Mn films became crystalline by the post-deposition annealing above 800 °C and the crystallinity of the films was continuously improved up to the annealing temperature of 1200 °C. It was shown that the annealed Ga2O3:Mn films possessed a monoclinic β-Ga2O3 phase having a textured structure with (400) and (?401) crystallographic planes oriented preferentially parallel to the substrate surface. The lattice parameters of the monoclinic β-Ga2O3 phase in the 1200 °C annealed Ga2O3:Mn films were measured to be a = 12.152 Å, b = 3.043 Å, and c = 5.785 Å.  相似文献   

5.
HfO2 films were deposited on silicon substrates by the oxygen-assisted decomposition of hafnium β-diketonates at temperatures in the range 400–550 °C. These films were characterized by using transmission electron microscopy, X-ray diffraction, electron microprobe analysis and measurements of dielectric and optical properties. It was found that the films were fine-grained (approximately 325 Å) nearly stoichiometric monoclinic HfO2. The films showed high resistance to most aqueous acids and bases. The deposits had a refractive index of 2.1 and an optical energy gap of 5.68 eV. The dielectric constant at 1 MHz was 22–25, and the dielectric strenght of the HfO2 films varied between 2 × 106 and 4.5 × 106 V cm?1. C-V measurements at 1 MHz indicated the presence of effective surface states which varied between 1.0 × 1011 and 6 × 1011 cmt?2 for films that were deposited at temperatures higher than 500 °C or that were annealed at above 750 °C if deposited at 400–450 °C. The VFB values were between ?0.6 and 0 V. The annealed films or films grown above 500 °C showed good bias-temperature stability. When positive bias and elevated temperatures were applied, the original C-V curve moved towards higher positive field values (0.2-0.5 V). After applying negative bias at elevated temperatures the C-V curved moved back in the direction of the original C-V curve. Measurements of the dependence of the current I on the electric field showed a dependence of IV2 over a wide range.  相似文献   

6.
The physical characteristics of SnOx(x≈2) films deposited onto Pyrex glass substrates by chemical vapour deposition are studied. The temperature dependence indicates that films deposited at 600 °C have good polycrystallinity. The electrical conductivity of the 600 °C films is mainly controlled by the variation in the SnCl4 vapour flow rate. A subsequent thermal annealing process can even reduce the sheet resistance to 400ω/□. In addition, the visible absorption shows that the 600 °C films tend to lose their transparency in the short wavelength range of the visible spectrum.  相似文献   

7.
《Thin solid films》2002,402(1-2):167-171
Boron nitride has for the first time been deposited from gaseous BBr3 and NH3 by means of atomic layer deposition. The deposition temperatures were 400 and 750 °C, and the total pressure was 10 torr. The BN films, deposited on silica substrates, showed a turbostratic structure with a c-axis of 0.70 nm at a deposition temperature of 750 °C as determined by X-ray diffraction. The films deposited at 400 °C were significantly less ordered. The film density was obtained by means of X-ray reflectivity, and it was found to be 1.65–1.70 and 1.90–1.95 g cm−3 for the films deposited at 400 and 750 °C, respectively. Furthermore, the films were, regardless of deposition temperature, fully transparent and very smooth. The surface roughness was 0.3–0.5 nm as measured by optical interferometry.  相似文献   

8.
We have studied the properties of thin ferroelectric films of barium strontium titanate (Ba,Sr)TiO3 (BSTO) obtained by RF ion-plasma deposition at various substrate temperatures in the 700–900°C range. It is established that BSTO films deposited at 700–800°C exhibit a polycrystalline structure. Beginning with 800°C, the film structure changes so that an (111)-oriented phase appears and becomes predominating. The effect of the deposition temperature on the grain size and the relationship between the structural features and electrical properties of the films are considered.  相似文献   

9.
Copper indium sulphide films were deposited for the first time by the brush plating technique at different electrolyte temperatures in the range of 30–80 °C and at a constant deposition current density of 5.0 mA cm?2. The Films exhibited single phase copper indium sulphide. The grain size increased with increase of electrolyte temperature. Optical band gap of the films varied in the range of 1.30–1.42 eV. Atomic force microscopy studies indicated that the grain size vary from 600 to 1,000 nm, with increase of substrate temperature. Solar cells fabricated with the films exhibited Voc of 650 mV, Jsc of 19.5 mA cm?2, ff of 0.73 and efficiency of 9.50 %.  相似文献   

10.
《Thin solid films》1987,149(1):61-64
Investigations of the microcrystalline structure of sputtered MoSi2 thin films deposited at temperatures in the range 60–500 °C are described. At low temperatures the films are amorphous, and in the higher range of temperature hexagonal MoSi2 is detected. Annealing the films at 960 °C to form the low resistivity tetragonal MoSi2 phase results in different grain sizes depending on the substrate temperature during deposition.  相似文献   

11.
Abstract

GaAs1‐xPx thin films have been deposited onto glass substrates at a rate of 50Å/min. in a vacuum of 5 x 10‐5 Torr using a successive evaporation method. Thin films of various compositions (X = 0.3–0.9) were obtained at gallium source temperature TGa = 870°C, arsenic source temperature TAs = 275°C, phosphorus source temperature TP = 330°‐363°C and substrate temperature Tsub = 265°‐330°C. Compositional, optical (absorption) and electrical properties of the films in a thickness range of 1300–1900 Å were determined by using an X‐ray diffractometer, a grating spectrometer and an electrometer respectively. The experimental results were compared with those for simultaneous evaporation and discussed from the atomistic viewpoints.

The values of △X/△Tsub are ‐ 7 x 10‐3 and ‐1 x 10‐3 °C‐1 for successive and simultaneous evaporation respectively, the difference of which can be explained by the absorption effect of a predeposited Ga layer in successive evaporation. The value of △X/△Tp is about +7 x 10‐3°C‐1 for the two evaporation methods, however, it levels off more distinctly at higher substrate temperatures. Absorption edge shift and relatively low resistivity suggest that successively vacuum‐deposited films have much more phosphorus vacancies and/or impurities than simultaneously vacuum‐deposited and chemically vapor‐deposited films.  相似文献   

12.
《Materials Letters》2005,59(24-25):2994-2997
Highly c-axis oriented LiNbO3 thin films have been deposited on Si (111) substrates by pulsed laser deposition. A stoichiometric sintered LiNbO3 is used as the target. The c-axis orientation and stoichiometry of LiNbO3 films are strongly influenced by substrate temperature and oxygen pressure. The substrate temperature 600 °C and oxygen pressure 20–30 Pa are found to be optimized parameters for the growth of textured film. The results showed that the size and the density of droplets decreased with increasing substrate temperature, and droplets would disappear when substrate temperature is increased above 600 °C. The surface microstructures of LiNbO3 films under optimized conditions are fine, uniform and dense. The AFM images ensured that the as-grown films are good enough to be integrated with the semiconductor devices.  相似文献   

13.
ZrO2 films were deposited on silicon substrates by oxygen-assisted decomposition of zirconium-β-diketonates at temperatures of 400–550°C. The deposits, fine-grained nearly stoichiometric monoclinic ZrO2, were hard and showed strong adherence to the substrate. The films were characterized by transmission electron microscopy, X-ray diffraction and electron microprobe analysis and by measuring their dielectric and optical properties. The index of refraction was found to be 2.18, and the optical energy band gap was found to be 5.16 eV. The dielectric constant at 1 MHz was 17–18, and the dielectric strength varied between 1 × 106 and 2.0 × 106 V cm?1. Capacitance-voltage measurements at 1 MHz indicated the presence of effective surface states with a concentration in the range (1.0?6.0) × 1011cm?2 for films deposited at temperatures above 500°C or for films deposited at 400–450°C and annealed at above 750°C. The flat-band voltages were between ?0.6 and + 0.2 V. The films showed satisfactory bias-temperature stability. The current-voltage characteristic followed an IV2 dependence for negative bias and an IV2.6 to IV3.4 dependence for positive bias.  相似文献   

14.
Thick films of Nb3Sn (in the ordered A-15 phase) have been synthesized by codeposition of the elements niobium and tin from separate electron-beam-heated sources onto heated rotating Hastelloy B tube substrates. Using a fixed deposition rate (approximately 60 Å s-1 effective at the tube surface), single-layer samples 2.8 μm and 7 μm thick were prepared at substrate temperatures ranging between 830 K and 1020 K. The samples were examined using scanning electron microscopy, electron microprobe analysis and X-ray diffraction. The transition from porous columnar to dense columnar growth was observed. Column diameters increased monotonically with substrate temperature. For substrate temperatures between 650 °C and 700 °C a very shiny deposit was formed with a 〈211〉 growth orientation. In layered structures formed by sequential deposition of Nb3Sn (about 420 Å layer-1) and yttrium (about 90 Å layer-1) the columnar growth observed in single- layer thick films appeared to be disrupted. Using the technique of fine layering, thick films of Nb3Sn with acceptable 50 Hz loss and outstanding critical current density have been prepared for superconducting power transmission line applications.  相似文献   

15.
Bi/Mo multilayer thin films are deposited on Si/SiO2/Pt substrates by direct current magnetron sputtering. The effect of annealing temperature on the microstructure, dielectric and electrical properties of the as-sputtered films is characterized systematically. X-ray diffraction data indicate that the films annealed at 450–600 °C are a mixture of diphase with the main phase Bi2MoO6 and secondary phase Bi2Mo2O9. Results of scanning electron microscope observation show that the films annealed at 500–550 °C are dense and uniform, in particular the films annealed at 500 °C exhibit optimal dielectric and electrical properties with dielectric constant as high as 37.5, dielectric loss 1.06 %, temperature coefficient of dielectric constant ?10.86 ppm °C?1 at 1 kHz, and leakage current density of 1.46 × 10?7 A mm?2 at an electric field of 18.2 kV mm?1. With the advantages of ultralow densification temperature (500 °C) and very high sputtering deposition rate (76 nm min?1), it is anticipated that thermal oxidation method of the sputtered Bi/Mo thin films could be a promising technique for fabrication of Bi2MoO6 ceramic thin film embedded-capacitors.  相似文献   

16.
Micro-crystalline diamond (MCD) and diamond like carbon (DLC) thin films were deposited on silicon (100) substrates by hot-filament CVD process using a mixture of CH4 and H2 gases at substrate temperature between 400–800°C. The microstructure of the films were studied by X-ray diffraction and scanning electron microscopy. The low temperature deposited films were found to have a mixture of amorphous and crystalline phases. At high temperatures (> 750°C) only crystalline diamond phase was obtained. Scanning electron micrographs showed faceted microcrystals of sizes up to 2μm with fairly uniform size distribution. The structure of DLC films was studied by spectroscopic ellipsometry technique. An estimate of the amount of carbon bonds existing insp 2 andsp 3 form was obtained by a specially developed modelling technique. The typical values ofsp 3/sp 2 ratio in our films are between 1·88–8·02. Paper presented at the poster session of MRSI AGM VI, Kharagpur, 1995  相似文献   

17.
Microstructural and surface morphological studies of Co (2.5%) doped ZnS thin films deposited at different substrate temperatures (TS) of 200, 400 and 600 °C by means of pulsed laser deposition are presented. The deposited films are in wurtzite-hexagonal crystal structure as confirmed by X-ray diffraction and Raman spectroscopy techniques. The films deposited at higher TS show columnar morphology, as evidence by transmission electron microscopy measurements. Images of the surface topography have been taken by atomic force microscopy (AFM) for the film deposited at different TS. The film deposited at TS of 200 °C shows cone-like structures while deposited at TS of 400 and 600 °C show columnar structures. A fractal analysis has been performed on AFM images to understand the microstructure and surface morphology of thin film at different TS. Fractal analysis also reveals the morphological changes in the film with increasing TS. The observed ferromagnetism is correlated with columnar growth of the film which can be used as diluted magnetic semiconductor for spintronic applications.  相似文献   

18.
《Thin solid films》1986,137(2):207-214
Conducting transparent films of indium tin oxide were deposited by 100 eV oxygen-ion-assisted deposition. A refractive index of 2.13 at 550 nm was obtained for films deposited onto ambient temperature substrates. The refractive index decreased with increasing substrate temperature to a value of 2.0 at 400°C. The sheet resistance of films 135 nm thick decreased from 800 Ω/□ for layers deposited onto room temperature substrates to around 25 Ω/□ at 400°C. Structural studies revealed that ion-assisted deposition onto ambient temperature substrates produced amorphous films, and that at temperatures above 100°C the films exhibit In2O3 crystallinity. In addition, it was found that the number of voids in the ion-bombarded films was reduced relative to that in films produced by conventional reactive evaporation.  相似文献   

19.
Highly transparent and conducting SnO2 films, as required in thin film heterojunction solar cells, were deposited onto Pyrex glass substrates by oxidation of SnCl2 in the temperature range 350–500°C. Oxygen with a flow rate of between 1 and 3.251 min-1 was used as both the carrier gas and the oxidizing agent. For films deposited in these conditions the resistivity varies from 10-2 to 10-3 Ω cm with transmission in the range 87%–71%. It was observed that both the resistivity and the transmission decrease with increasing deposition temperature. The resistivity of films deposited at a fixed deposition temperature passes through a minimum as the oxygen flow rate is increased. Hence, SnO2 films with low resistivity and high transmission can be produced by the oxidation of SnCl2 at relatively low temperatures using the oxygen flow rate corresponding to the minimum resistivity. For example, in the present work, low resistivity (4.4 × 10-3 Ω cm) and high transmission (87%) were observed for films deposited at 400°C with an oxygen flow rate of 1.81 min-1. The effects of the deposition temperature, oxygen flow rate and deposition time on the thickness, deposition rate, resistivity and absorption coefficient are discussed in detail.  相似文献   

20.
Copper bismuth sulfide thin films were deposited at 200 °C, 300 °C, 400 °C and 500 °C on the glass substrates by electron beam evaporation method. X-ray diffraction study revealed that the copper bismuth sulfide films of single and mixed phases were formed as a function of substrate temperatures. Substrate temperature of 300 °C and 400 °C formed single phase Cu4Bi4S9 and Cu4Bi5S10 films respectively whereas substrate temperature of 500 °C formed mixed phases of Cu4Bi4S9 and Cu4Bi5S10 film. Crystallite size, dislocation density and microstrain of the films were modified by the various substrate temperatures. Surface morphology of the film Cu4Bi5S10 deposited at 400 °C examined by scanning electron microscopy showed the distribution of spherical shaped particles on the film surface. The presence of copper, bismuth and sulfur elements in the deposited films was confirmed using energy dispersive spectral studies. The calculated direct optical band gap energy of the films deposited at different substrate temperature varied from 1.47 to 1.64 eV and the absorption coefficient is in the order of 106 cm?1.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号