共查询到20条相似文献,搜索用时 31 毫秒
1.
M. Grosser 《Applied Surface Science》2010,256(14):4564-261
In this study, we focus on the influence of annealing time tPDA (i.e. 30 min and 630 min) on the room-temperature resistivity of electron-beam-evaporated titanium/platinum thin films when exposed to thermal loads up to temperatures TPDA of 700 °C. The titanium has a fixed thickness of 5 nm and serves as an adhesion layer. The thickness df,Pt of the platinum top layer is varied between 21 and 97 nm. Up to annealing temperatures of 450 °C, the film resistivity of the bi-layer system is linearly correlated with the reciprocal platinum film thickness independent of tPDA, as expected from the size effect. At tPDA = 30 min, the change in intrinsic film stress dominates the electrical behavior in this annealing regime, predominantly at large df,Pt values. Compared to tPDA = 630 min, however, the increase in resistivity especially at low platinum film thickness is substantially larger demonstrating that titanium starts to diffuse at these long annealing times even at moderate temperatures. At TPDA = 600 °C, the diffusion of titanium into the top layer leads to an enhanced increase in film resistivity ρf, especially at low platinum thicknesses and low annealing times, as the mean penetration depth of diffused titanium is under these conditions in order of df,Pt. Above TPDA = 600 °C, ρf is slightly increased at tPDA = 30 min. At tPDA = 630 min, however, the film resistivity is decreased at df,Pt < 58 nm. This is attributed to grain growth and re-crystallization effects. Furthermore, the mean penetration depths of titanium substantially exceed df,Pt resulting predominantly in TixOy formation on the top film surface and hence, having low impact on ρf. 相似文献
2.
Jian Zhu Shen-Wei Bai Jun-Wu Zhao Jian-Jun Li 《Applied Physics A: Materials Science & Processing》2009,97(2):431-436
Permalloy (Py) films were deposited on Si(111) or Corning 0211 glass substrates. There were two deposition temperatures: T
s=room temperature (RT) and T
s=270°C. The film thickness (t
f) ranges from 10 to 130 nm. The crystal structure properties of the films were studied by X-ray diffraction and transmission
electron microscopy. Mechanical properties (including Young’s modulus E
f and hardness H
f) of each film were measured by the nanoindentation (NI) technique. E
f of the Py/Si(111) films was checked again by the laser induced surface acoustic wave (LA-SAW) technique. It was found that
the NI technique is best suited for the measurements of E
f and H
f, but only when the sample belongs to the (soft film)/(soft substrate) system, such as the Py/glass film. For the (soft film)/(hard
substrate) system, such as the Py/Si(111) film, the NI technique often provides higher values of E
f and H
f than expected. The anomalous phenomenon, associated with the NI technique may be related to the anisotropic crystal structures
in the Py films on different kinds of substrates. From this study, we conclude that [E
f of Py/Si(111)]>[E
f of Py/glass] and [H
f of Py/Si(111)]>[H
f of Py/glass]. The good mechanical properties of the Py/Si(111) film make it a better candidate for recording head applications. 相似文献
3.
Xu Fei Ying Wan Haiming Zhang Zhanchen Cui Daming Zhang 《Applied Physics A: Materials Science & Processing》2009,96(2):467-472
A linear fluorinated bis-phenol-A novolac resin (LFAR) for optical waveguide was synthesized based on 4,4′-(hexafluoro-isopropylidene)diphenol,
epoxy chloropropane and formaldehyde. Negative fluorinated photoresist (FP) was made by composing the LFAR, diphenyl iodonium
salt and solvent. The film, which was made by spin-coating FP, had good UV light lithograph sensitivity, large hardness and
high glass transition temperature (T
g
>170°C, after crosslinking). Low-loss optical waveguides with very smooth top surface were fabricated from the resulting FP
by direct UV exposure and chemical development. For waveguides without upper cladding, the propagation loss of the channel
waveguides was measured to be 0.21 dB/cm at 1550 nm. 相似文献
4.
H. Kim G. P. Kushto R. C. Y. Auyeung A. Piqué 《Applied Physics A: Materials Science & Processing》2008,93(2):521-526
Fluorine-doped tin oxide (FTO) thin films have been investigated as an alternative to indium tin oxide anodes in organic photovoltaic
devices. The structural, electrical, and optical properties of the FTO films grown by pulsed laser deposition were studied
as a function of oxygen deposition pressure. For 400 nm thick FTO films deposited at 300°C and 6.7 Pa of oxygen, an electrical
resistivity of 5×10−4 Ω-cm, sheet resistance of 12.5 Ω/□, average transmittance of 87% in the visible range, and optical band gap of 4.25 eV were obtained. Organic photovoltaic (OPV)
cells based on poly(3-hexylthiophene)/[6,6]-phenyl-C61-butyric acid methyl ester bulk heterojunctions were prepared on FTO/glass electrodes and the device performance was investigated as a function of FTO
film thickness. OPV cells fabricated on the optimum FTO anodes (∼300–600 nm thick) exhibited power conversion efficiencies
of ∼3%, which is comparable to the same device made on commercial ITO/glass electrodes (3.4%). 相似文献
5.
Photosensitive poly(MMA-co-GMA) for optical waveguide was synthesized, and the refractive index of the polymer film was tuned
in the range of 1.481–1.588 at 1550 nm by mixing with bis-phenol-A epoxy resin. The film, which was made by spinning coated
the poly(MMA-co-GMA) with photo initiator, had good UV light lithograph sensitivity, high glass transition temperature (T
g
: 153°C, after crosslinking) and good thermal stabilities (T
d
: up to 324°C, after crosslinking). The optical waveguides with very smooth top surface were fabricated from the resulting
polymer by direct UV exposure and chemical development. For waveguides with cladding, the propagation losses of the channel
waveguides were measured to be below 3 dB/cm at 1550 nm. 相似文献
6.
Hartmann L Gorbatschow W Hauwede J Kremer F 《The European physical journal. E, Soft matter》2002,8(2):145-154
The molecular dynamics in thin films (18 nm-137 nm) of isotactic poly(methyl methacrylate) (i-PMMA) of two molecular weights
embedded between aluminium electrodes are measured by means of dielectric spectroscopy in the frequency range from 50 mHz
to 10 MHz at temperatures between 273 K and 392 K. The observed dynamics is characterized by two relaxation processes: the
dynamic glass transition (α-relaxation) and a (local) secondary β-relaxation. While the latter does not depend on the dimensions
of the sample, the dynamic glass transition becomes faster (≤2 decades) with decreasing film thickness. This results in a
shift of the glass transition temperature T
g to lower values compared to the bulk. With decreasing film thickness a broadening of the relaxation time distribution and
a decrease of the dielectric strength is observed for the α-relaxation. This enables to deduce a model based on immobilized
boundary layers and on a region displaying a dynamics faster than in the bulk. Additionally, T
g was determined by temperature-dependent ellipsometric measurements of the thickness of films prepared on silica. These measurements
yield a gradual increase of T
g with decreasing film thickness. The findings concerning the different thickness dependences of T
g are explained by changes of the interaction between the polymer and the substrates. A quantitative analysis of the T
g shifts incorporates recently developed models to describe the glass transition in thin polymer films.
Received 12 August 2001 and Received in final form 16 November 2001 相似文献
7.
R. Eichele W. Kern R. P. Huebener 《Applied Physics A: Materials Science & Processing》1981,25(2):95-103
We have studied the influence of oxygen on the superconducting properties of thin films of lead, indium and tin deposited
on glass or sapphire substrates. In addition, the morphological microstructure was investigated by scanning electron microscopy.
The film thickness was 1.0 μm, and the partial pressure of O2 during the film deposition was raised up to 1×10−4 Torr. In all three materials the development of a granular structure and a strong increase in the residual electric resistivity
was observed due to the O2-treatment. Whereas in the Pb films no change of the critical temperature was found, the In films deposited on glass substrates
showed a slight increase ofT
c due to the oxygen. The strongest increase ofT
c (up to 8%) was observed in the O2-treated Sn films. These results are discussed in terms of the McMillan theory. From our measurements of the critical current
densityj
c we conclude that edge pinning is dominant in the undoped films. All three materials showed a strong increase ofj
c due to the O2-treatment which must be interpreted in terms of bulk pinning. 相似文献
8.
Ellison CJ Kim SD Hall DB Torkelson JM 《The European physical journal. E, Soft matter》2002,8(2):155-166
Fluorescence intensity measurements of chromophore-doped or -labeled polymers have been used for the first time to determine
the effects of decreasing film thickness on glass transition temperature, T
g, the relative strength of the glass transition, and the relative rate of physical aging below T
g in supported, ultrathin polymer films. The temperature dependence of fluorescence intensity measured in the glassy state
of thin and ultrathin films of pyrene-doped polystyrene (PS), poly(isobutyl methacrylate) (PiBMA), and poly(2-vinylpyridine)
(P2VP) differs from that in the rubbery state with a transition at T
g. Positive deviations from bulk T
g are observed in ultrathin PiBMA and P2VP films on silica substrates while substantial negative deviations from bulk T
g are observed in ultrathin PS films on silica substrates. The relative difference in the temperature dependences of fluorescence
intensity in the rubbery and glassy states is usually reduced with decreasing film thickness, indicating that the strength
of the glass transition is reduced in thinner films. The temperature dependence of fluorescence intensity also provides useful
information on effects of processing history as well as on the degree of polymer-substrate interaction. In addition, when
used as a polymer label, a mobility-sensitive rotor chromophore is demonstrated to be useful in measuring relative rates of
physical aging in films as thin as 10 nm.
Received 21 August 2001 相似文献
9.
C. Scilletta S. Orlando M. Servidori E. Cappelli G. Conte P. Ascarelli 《Applied Physics A: Materials Science & Processing》2008,93(3):783-787
Thin carbon films have been deposited in vacuum (∼10−4 Pa) on Si substrates by pulsed laser ablation of a graphite target using a Nd:YAG laser operating in the near infrared region
(λ=1064 nm). The samples have been deposited at different substrate temperatures (T
sub) ranging from room temperature (RT) to 800°C. X-ray diffraction analysis established the progressive formation of nanosized
graphene structures as T
sub increased. In fact, film structure evolves from almost amorphous to nanostructured phase characterized by graphene layers
oriented perpendicularly to the film plane. The film density, evaluated by X-ray reflectivity measurements, is strongly affected
by T
sub. At RT the film density is similar to the graphite one, while it decreases at higher T
sub. The electrical properties of the samples have been characterized by field emission measurements. The parameters describing
the emitter properties (threshold field E
th and field enhancement factor β) have been evaluated using variable anode-to-cathode distance method. Samples deposited at low T
sub have shown the best emission properties, presenting lower E
th and larger β values than those deposited at higher T
sub. This is mainly attributed to the sensible density variation, which is in competition with the slighter augment of mean nanoparticle
size. 相似文献
10.
Determination of the optimal parameters for the fabrication of ZnO thin films prepared by spray pyrolysis method 总被引:1,自引:0,他引:1
In this work, ZnO thin films have been prepared by spray pyrolysis deposition method on the glass substrates. The effect of
deposition parameters, such as deposition rate, substrate temperature and solution volume has been studied by X-ray diffraction
(XRD) method, UV–Vis–NIR spectroscopy, scanning electron microscopy (SEM), and electrical measurements. The XRD patterns indicate
polycrystalline wurtzite structure with preferred direction along (0 0 2) planes. Thin films have transparency around 90%
in the visible range. The optical band gap was determined at 3.27 eV which did not change significantly. Evolution of electrical
results containing the carriers’ density, sheet resistance and resistivity are in agreement with structural results. All the
results suggest the best deposition parameters are: deposition rate, R = 3 ml/min, substrate temperature, T
s = 450°C and thickness of the thin films t = 110–130 nm. 相似文献
11.
《Solid State Ionics》2006,177(19-25):1875-1878
Zinc gallate (ZnGa2O4) thin film phosphors have been formed on ITO glass substrates by a chemical solution method with starting materials of zinc acetate dihydrate, gallium nitrate hydrate and 2-methoxiethanol as a solution. The thin films were firstly dried at 100 °C and fired at 500 °C for 30 min and then, annealed at 500 °C and 600 °C for 30 min under an annealing atmosphere of 3% H2/Ar. XRD patterns of the thin film phosphors showed (311) and (220) peak indicating ZnGa2O4 crystalline phase in which all the (311) peaks of the film phosphors synthesized on ITO glass and soda-lime glass revealed high intensity with increasing annealing temperature from 500 °C to 600 °C. The ZnGa2O4 thin film phosphors represented marked change in AFM surface morphologies according to an annealing temperature under an annealing atmosphere (3% H2/Ar). The film phosphor, annealed at 600 °C, showed the embossed pattern with relatively regular spacing in AFM surface morphology. The ZnGa2O4 thin film phosphors formed on ITO glass, which were annealed at different temperatures and showed distinctive spectra with peak wavelengths of 434 nm and 436 nm in the blue emission region. 相似文献
12.
The resistivity of transparent conducting Al‐ and Ga‐doped ZnO (AZO and GZO) thin films prepared with a thickness in the range from 20 to 200 nm on glass substrates at a temperature below 200 °C was found to increase with exposure time when tested in a high humidity environment (air at 90% relative humidity and 60 °C). The resistivity stability (resistivity increase) was considerably affected by the thin film thickness. In particular, thin films with a thickness below about 50 nm were very unstable. The increase in resistivity is interpreted as carrier transport being dominated by grain boundary scattering resulting from the trapping of free electrons due to oxygen adsorption on the grain boundary surface. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
13.
M. Takeguchi M. Shimojo K. Furuya 《Applied Physics A: Materials Science & Processing》2008,93(2):439-442
Electron beam induced deposition was performed using a Pt(PF3)4 precursor gas. Self-standing nanowires were produced on the edge of a molybdenum film, followed by two post-deposition processes;
electron beam irradiation at room temperature and heating at about 400 K in vacuum. The as-deposited nanowires were composed
of an amorphous phase, of which the dominant composition was platinum but containing a small amount of phosphorus impurity.
After irradiating with a 300 keV electron beam, the amorphous nanowires were transformed to crystalline ones. By heating,
the as-deposited nanowires became single-crystal platinum with a large grain size and the phosphorus content disappeared. 相似文献
14.
Hai Wang Yong Liu Hong Huang Minyi Zhong Hui Shen Yuanhao Wang Hongxing Yang 《Applied Surface Science》2009,255(22):9020-9025
Low resistance dye-sensitized solar cells (DSSCs) based on all-titanium substrates were proposed in this paper. To minimize the internal resistance of DSSCs, the titanium wires and titanium sheets were used as the substrates of the photoanode and the counter electrode, respectively. Compared with the FTO substrate, titanium wires could absorb much diffused light by back reflection since the reflectivity in the titanium sheet was highly increased up to 53.12%. Furthermore, the transmittance of the front cover was increased by 13.2% using the super white glass instead of FTO substrate. The thickness of TiO2 thin film coated on titanium wire was optimized to achieve a high cell performance. The efficiency of 5.6% for the cell was obtained with a Jsc of 15.41 mA cm−2, Voc of 0.59 V, and FF of 0.62. The results showed that the titanium-based DSSCs had superiority for producing the large-scale DSSCs without metal grid line. 相似文献
15.
S. Kim S. A. Hewlett C. B. Roth J. M. Torkelson 《The European physical journal. E, Soft matter》2009,30(1):83-92
Using ellipsometry, we characterized the nanoconfinement effect on the glass transition temperature (T
gof supported polystyrene (PS) films employing two methods: the intersection of fits to the temperature (Tdependences of rubbery- and glassy-state thicknesses, and the transition mid-point between rubbery- and glassy-state expansivities.
The results demonstrate a strong effect of thickness: Tg(bulk)-Tg(23 nm) = 10 °\ensuremath T_{{\rm g}}({\rm bulk})-T_{{\rm g}}(23{\,\mbox{nm}})= 10 ^{\circ} C. The T -range needed for accurate measurement increases significantly with decreasing thickness, an effect that arises from the
broadening of the transition with confinement and a region below T
g where expansivity slowly decreases with decreasing T . As determined from expansivities, the T
g breadth triples in going from bulk films to a 21-nm-thick film; this broadening of the transition may be a more dramatic
effect of confinement than the T
g reduction itself. In contrast, there is little effect of confinement on the rubbery- and glassy-state expansivities. Compared
with ellipsometry, T
g ’s from fluorescence agree well in bulk films but yield lower values in nanoconfined films: T
g(bulk) - T
g(23 nm) = 15° C via fluorescence. This small difference in the T
g confinement effect reflects differences in how fluorescence and ellipsometry report “average T
g ” with confinement. With decreasing nanoscale thickness, fluorescence may slightly overweight the contribution of the free-surface
layer while ellipsometry may evenly weight or underweight its contribution. 相似文献
16.
A. Elfalaky 《Applied Physics A: Materials Science & Processing》1995,60(1):87-91
Antimony thin films were vacuum deposited on glass substrates at room temperature. X-ray structural studies were performed. The thickness dependence of both the de electrical resistivity and the Hall coefficient were earried out at room temperature over a thickness range from 29 nm to 216 nm. The type of conduction, the concentration and the mobility of charge carriers were revealed.Analysis incorporating the electrical resistivity and the Hall effect data has led to the determination of the specular and non-specular size-effect parameters. Parameters such as the bulk resistivity (
0), bulk mean free path (
0), grain-boundary transmission coefficient (t), external surface parameters (U), surface scattering factor (p) and grain-boundary parameter (V), were all evaluated without using any adjusting parameters.Beside the background contribution to the film resistivity, an estimation of the contribution of the surface and grain-boundary to the film resistivity was also carried out. 相似文献
17.
K. Fukao Y. Oda K. Nakamura D. Tahara 《The European physical journal. Special topics》2010,189(1):165-171
The glass transition temperature and the dynamics of the α-process have been investigated using dielectric relaxation spectroscopy
for single and stacked thin films of poly(2-chlorostyrene) (P2CS). The stacked film consists of 10 layers of single thin films
with thickness of 12 nm or 18 nm. The glass transition temperature T
g
of the single thin films of P2CS is found to decrease with decreasing film thickness in a similar way as observed for polystyrene
thin films. The magnitude of the depression of T
g
for the stacked thin films is larger than that of the single thin films with corresponding thickness. The depression of the
temperature at which the dielectric loss shows a peak due to the α-process at a given frequency, T
α, is larger than that of the single thin films, although the magnitude is smaller than that of T
g
. Annealing at a high temperature could cause the T
g
and T
α of the stacked thin films to approach the values of the bulk system. 相似文献
18.
Amorphous ErSiO films have been fabricated on p-type Si (001) substrates using rf magnetron sputtering technique. X-ray diffraction,
high-resolution transmission electron microscopy, and atomic force microscopy were employed to investigate the samples. It
is found that ErSiO film exhibits a flat surface, a sharp interface and superior electrical properties after post-deposition
annealing in O2 ambience for 30 min at 450°C. The effective dielectric constant of the film is measured to be 14.2, and the effective oxide
thickness reaches 1.9 nm, with a low leakage current density of 1.1×10−4 A/cm2 at an electric field of 1 MV cm−1 after annealing at 450°C. The obtained characteristics make the amorphous ErSiO films a promising substitute for SiO2 as a high-k gate dielectric. 相似文献
19.
Thin films of CdSxTe1-x were deposited by the pulse electrodeposition technique using cadmium sulfate, sodium thiosulfate, and tellurium dioxide
on titanium and conducting glass substrates. Structural studies indicated the formation of polycrystalline films possessing
hexagonal structure. The resistivity varies from 53 Ω cm to 8 Ω cm as the stochiometric coefficient “x” value decreases from 1 to 0. The carrier concentration increases with CdTe concentration. It is observed that as the post-heat
treatment temperature increases, the photosensitivity also increases. It is observed that a post-heat treatment temperature
of 550 °C results in high photosensitivity as well as low light resistance. The optical constants, refractive index (n) and extinction coefficient (k) were evaluated from the transmission spectra of the films of different composition. 相似文献
20.
P. Müller-Buschbaum M. Strzelczyk M. Tolan W. Press 《Zeitschrift für Physik B Condensed Matter》1995,98(1):89-95
X-ray scattering experiments of liquid films on top of solid substrates were performed. With a short pulse disturbance, caused by a temperature difference between the substrate and the vapour in the X-ray cell, the wetting film thickness is reduced. Afterwards the time dependence of the growing film is monitored by X-ray reflectivity measurements in the region of total external reflection. We have examined CCl4- and CCl3Br-films on top of silicon wafers and CCl3Br on glass/gold and glass/silver substrates. The film thickness as function of time is explained by the Kolmogorov growth model. From the data we obtain rather long time constants and the dimensiond=2 of the growing process 相似文献