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1.
A platinum/reduced graphene oxide (Pt/rGO) nanocomposite acting as a counter electrode (CE) was fabricated using a chemical bath deposition method for In2O3-based dye-sensitized solar cell (DSSC) via sol-gel technique. The report analyzes the morphological and electrochemical impedance spectroscopy of the annealing Pt/rGO films at 350, 400, and 450 °C. Micrograph images obtained from field emission scanning electron microscopy demonstrated the annealed films are highly porous. The energy-dispersive X-ray results show that the carbon atoms were homogeneously distributed on the film annealed at 400 °C. A good photovoltaic performance was exhibited with high photocurrent density of 8.1 mA cm−2 and power conversion efficiency (η) of 1.68 % at the Pt/rGO CE annealed at 400 °C. The employed electrochemical impedance spectroscopy analysis quantifies that the Pt/rGO films annealed at 400 °C provide more efficient charge transfer with the lowest effective recombination rate and high electron life time, hence improving the performance of Pt/rGO CE. 相似文献
2.
High- k gate dielectric hafnium dioxide films were grown on Si (100) substrate by pulsed laser deposition at room temperature. The
as-deposited films were amorphous and that were monoclinic and orthorhombic after annealed at 500°C in air and N 2 atmosphere, respectively. After annealed, the accumulation capacitance values increase rapidly and the flat-band voltage
shifts from −1.34 V to 0.449 V due to the generation of negative charges via post-annealing. The dielectric constant is in
the range of 8–40 depending on the microstructure. The I–V curve indicates that the films possess of a promising low leakage
current density of 4.2×10 −8 A/cm 2 at the applied voltage of −1.5 V. 相似文献
3.
The electrical characteristics of thin TiO 2 films prepared by metal–organic chemical vapor deposition grown on a p-type InP substrate were studied. For a TiO 2 film of 4.7 nm on InP without and with ammonium sulfide treatment, the leakage currents are 8.8×10 −2 and 1.1×10 −4 A/cm 2 at +2 V bias and 1.6×10 −1 and 8.3×10 −4 A/cm 2 at −2 V bias. The lower leakage currents of TiO 2 with ammonium sulfide treatment arise from the improvement of interface quality. The dielectric constant and effective oxide
charge number density are 33 and 2.5×10 13 cm 2, respectively. The lowest mid-gap interface state density is around 7.6×10 11 cm −2 eV −1. The equivalent oxide thickness is 0.52 nm. The breakdown electric field increases with decreasing thickness in the range
of 2.5 to 7.6 nm and reaches 9.3 MV/cm at 2.5 nm. 相似文献
4.
Polycrystalline samples of Pr 1−x
Sr
x
Fe 0.8Co 0.2 O 3−δ
( x=0.1, 0.2, 0.3) (PSFC) were prepared by the combustion synthesis route at 1200°C. The structure of the polycrystalline powders
was analysed with X-ray powder diffraction data. The X-ray diffraction (XRD) patterns were indexed as the orthoferrite similar
to that of PrFeO 3 having a single-phase orthorhombic perovskite structure (Pbnm). Pr 1−x
Sr
x
Fe 0.8Co 0.2O 3−δ
( x=0.1, 0.2, 0.3) films have been deposited on yttria-stabilized zirconia (YSZ) single-crystal substrates at 700°C by pulsed
laser deposition (PLD) for application to thin film solid oxide fuel cell cathodes. The structure of the films was analysed
by XRD, scanning electron microscopy (SEM) and atomic force microscopy (AFM). All films are polycrystalline with a marked
texture and present pyramidal grains in the surface with different size distributions. Electrochemical impedance spectroscopy
(EIS) measurements of PSFC/YSZ single crystal/PSFC test cells were conducted. The Pr 0.7Sr 0.3Fe 0.8Co 0.2O 3−δ
film at 850°C presents a lower area specific resistance (ASR) value, 1.65 Ω cm 2, followed by the Pr 0.8Sr 0.2Fe 0.8Co 0.2O 3−δ
(2.29 Ω cm 2 at 850°C) and the Pr 0.9Sr 0.1Fe 0.8Co 0.2O 3−δ
films (5.45 Ω cm 2 at 850°C). 相似文献
5.
Excellent dielectric frequency, bias, and temperature stability of bismuth silicate (Bi 2SiO 5, BSO) thin films with a low dielectric loss has been obtained in this study. The thin films were prepared on Pt/Ti/SiO 2/Si substrates by a chemical solution deposition method at a relatively low annealing temperature of 500 °C. The BSO films have a preferred growth along (200) orientation with dense fine-grained surface morphology. The dielectric constant and dielectric loss of the thin film annealed at 500 °C are 57 and 0.01, respectively, at 100 kHz, with little change between 1 kHz and 100 kHz and in the bias electric field range between −250 kV/cm and 250 kV/cm, indicating that the thin film exhibits a low dielectric loss as well as excellent frequency and bias field stability. The dielectric-temperature measurements confirmed that the BSO thin film annealed at 500 °C also has good temperature stability between 150 K and 450 K. Our results suggest that the BSO thin films have potential applications in the next-generation integrated capacitors. 相似文献
6.
Nanosized IrO 2 electrocatalysts ( d ~ 7–9 nm) with specific surface area up to 100 m 2 g −1 were synthesized and characterized for the oxygen evolution reaction in a solid polymer electrolyte (SPE) electrolyzer. The
catalysts were prepared by a colloidal method in aqueous solution and a subsequent thermal treatment. An iridium hydroxide
hydrate precursor was obtained at ~100 °C, which was, successively, calcined at different temperatures from 200 to 500 °C.
The physico-chemical characterization was carried out by X-ray diffraction (XRD), thermogravimetry–differential scanning calorimetry
(TG–DSC) and transmission electron microscopy (TEM). IrO 2 catalysts were sprayed onto a Nafion 115 membrane up to a loading of 3 mg cm −2. A Pt catalyst was used at the cathode compartment with a loading of 0.6 mg cm −2. The electrochemical activity for water electrolysis of the membrane-electrode assemblies (MEAs) was investigated in a single
cell SPE electrolyzer by steady-state polarization curves, impedance spectroscopy and chrono-amperometric measurements. A
maximum current density of 1.3 A cm −2 was obtained at 1.8 V and 80 °C for the IrO 2 catalyst calcined at 400 °C for 1 h. A stable performance was recorded in single cell for this anode catalyst at 80 °C. The
suitable catalytic activity and stability of the most performing catalyst were interpreted in terms of proper combination
between nanostructure and suitable morphology. 相似文献
7.
Nanostructured TiO 2 thin films were deposited on quartz glass at room temperature by sol–gel dip coating method. The effects of annealing temperature
between 200 ∘C to 1100 ∘C were investigated on the structural, morphological, and optical properties of these films. The X-ray diffraction results
showed that nanostructured TiO 2 thin film annealed at between 200 ∘C to 600 ∘C was amorphous transformed into the anatase phase at 700 ∘C, and further into rutile phase at 1000 ∘C. The crystallite size of TiO 2 thin films was increased with increasing annealing temperature. From atomic force microscopy images it was confirmed that
the microstructure of annealed thin films changed from column to nubbly. Besides, surface roughness of the thin films increases
from 1.82 to 5.20 nm, and at the same time, average grain size as well grows up from about 39 to 313 nm with increase of the
annealing temperature. The transmittance of the thin films annealed at 1000 and 1100 ∘C was reduced significantly in the wavelength range of about 300–700 nm due to the change of crystallite phase. Refractive
index and optical high dielectric constant of the n-TiO 2 thin films were increased with increasing annealing temperature, and the film thickness and the optical band gap of nanostructured
TiO 2 thin films were decreased. 相似文献
8.
Nitrogen ions were implanted in GaAs 1−xP x (x=0.4; 0.65) at room temperature at various doses from 5×10 12 cm −2 to 5×10 15 cm −2 and annealed at temperatures from 600°C up to 950°C using a sputtered SiO 2 encapsulation to investigate the possibility of creating isoelectronic traps by ion implantation. Photoluminescence and channeling
measurements were performed to characterize implanted layers. The effects of damage induced by optically inactive neon ion
implantation on photoluminescence spectrum were also investigated. By channeling measurements it was found that damage induced
by nitrogen implantation is removed by annealing at 800°C. A nitrogen induced emission intensity comparable to the intensity
of band gap emission for unimplanted material was observed for implanted GaAs 0.6P 0.4 after annealing at 850°C, while an enhancement of the emission intensity by a factor of 180 as compared with an unimplanted
material was observed for implanted GaAs 0.35P 0.65 after annealing at 950°C. An anomalous diffusion of nitrogen atoms was found for implanted GaAs 0.6P 0.4 after annealing at and above 900°C. 相似文献
9.
Thermally stimulated current (TSC) measurements performed in the 100 K–400 K temperature range on Bi 4Ti 3O 12 (BiT) thin films annealed at 550 °C and 700 °C had revealed two trapping levels having activation energies of 0.55 eV and
0.6 eV. The total trap concentration was estimated at 10 15 cm −3 for the samples annealed at 550 °C and 3×10 15 cm −3 for a 700 °C annealing and the trap capture cross-section was estimated about 10 −18 cm 2. From the temperature dependence of the dark current in the temperature range 20 °C–120 °C the conduction mechanism activation
energy was found to be about 0.956–0.978 eV. The electrical conductivity depends not only on the sample annealing temperature
but also whether the measurement is performed in vacuum or air. The results on the dark conductivity are discussed considering
the influence of oxygen atoms and oxygen vacancies.
Received: 28 January 1998 / Accepted: 8 January 1999 / Published online: 5 May 1999 相似文献
10.
We report white light emission from a Ga-doped ZnO/p-GaN heterojunction light-emitting diode which was fabricated by growing
gallium-doped ZnO film on the p-GaN in water at 90°C. As determined from Ga-doped ZnO films grown on (111) oriented MgAl 2O 4 spinel single crystal substrates, thermal treatment at 600°C in nitrogen ambient leads to a carrier concentration of 3.1×10 20 cm −3 (and carrier mobility of 28 cm 2/Vs) which is two orders of magnitude higher than that of the undoped films. Electroluminescence emissions at wavelengths
of 393 nm (3.155 eV) and 529.5 nm (2.4 eV) were observed under forward bias in the heterojunction diode and white light could
be visibly observed. The high concentration of electrons supplied from the Ga-doped ZnO films helped to enhance the carrier
recombination and increase the light-emitting efficiency of the heterojunction diode. 相似文献
11.
Present p-type ZnO films tend to exhibit high resistivity and low carrier concentration, and they revert to their natural n-type state
within days after deposition. One approach to grow higher quality p-type ZnO is by codoping the ZnO during growth. This article describes recent results from the growth and characterization
of Zr–N codoped p-type ZnO thin films by pulsed laser deposition (PLD) on (0001) sapphire substrates. For this work, both N-doped and Zr–N
codoped p-type ZnO films were grown for comparison purposes at substrate temperatures ranging between 400 to 700 °C and N 2O background pressures between 10 −5 to 10 −2 Torr. The carrier type and conduction were found to be very sensitive to substrate temperature and N 2O deposition pressure. P-type conduction was observed for films grown at pressures between 10 −3 to 10 −2 Torr. The Zr–N codoped ZnO films grown at 550 °C in 1×10 −3 Torr of N 2O show p-type conduction behavior with a very low resistivity of 0.89 Ω-cm, a carrier concentration of 5.0×10 18 cm −3, and a Hall mobility of 1.4 cm 2 V −1 s −1. The structure, morphology and optical properties were also evaluated for both N-doped and Zr–N codoped ZnO films. 相似文献
12.
Nanocrystalline AlN thin films were prepared via DC sputtering technique at different substrate temperature. The crystal orientation
and particle size of aluminum nitride thin films were investigated by XRD analysis. Study indicated that the sample contained
pure phase hexagonal AlN nanoparticles with a single peak corresponding to the (100) planes. The peak at 665 cm −1 in the FTIR spectrum of film was assigned to the LO phonon of hexagonal AlN. The particle size of the film, prepared at substrate
temperature 200°C was about 9.5 nm, as investigated by atomic force microscope. Field emission study indicated that it can
be used as a good field emitter. Turn-on field (E to) of 15.02 V/μm was observed for the AlN films synthesized at substrate temperature 200°C. Dielectric constant of the AlN
film was found nearly independent of frequencies in the measured frequency range 1 KHz to 1 MHz, i.e. in the audio frequency range. The values of dielectric constant ( ε) were 10.07, 9.46 and 8.65 for the film prepared at 70°C, 150°C and 200°C, respectively, at frequency 1 KHz. 相似文献
13.
CW CO 2-laser annealing of arsenic implanted silicon was investigated in comparison with thermal annealing. Ion channeling, ellipsometry,
and Hall effect measurements were performed to characterize the annealed layers and a correlation among the different methods
was made. The laser annealing was done with power densities of 100 to 640 W cm −2 for 1 to 20 s. It was found that the lattice disorder produced during implantation can be completely annealed out by laser
annealing with a power density of 500 W cm −2 and the arsenic atoms are brought on lattice sites up to 96±2%. The maximum sheet carrier concentration of 6×10 15 cm −2 was obtained for 1×10 16 cm −2 implantation after laser annealing, which was up to 33% higher than that after thermal annealing at 600 to 900°C for 30 min. 相似文献
14.
SnO 2 thin films have been deposited on glass substrates by pulsed Nd:YAG laser at different oxygen pressures, and the effects
of oxygen pressure on the physical properties of SnO 2 films have been investigated. The films were deposited at substrate temperature of 500°C in oxygen partial pressure between
5.0 and 125 mTorr. The thin films deposited between 5.0 to 50 mTorr showed evidence of diffraction peaks, but increasing the
oxygen pressure up to 100 mTorr, three diffraction peaks (110), (101) and (211) were observed containing the SnO 2 tetragonal structure. The electrical resistivity was very sensitive to the oxygen pressure. At 100 mTorr the films showed
electrical resistivity of 4×10 −2 Ω cm, free carrier density of 1.03×10 19 cm −3, mobility of 10.26 cm 2 V −1 s −1 with average visible transmittance of ∼87%, and optical band gap of 3.6 eV. 相似文献
15.
(La 0.5Sr 0.5)CoO 3 (LSCO) thin films have been fabricated on silicon substrate by the pulsed laser deposition method. The effects of substrate
temperature and post-annealing condition on the structural and electrical properties are investigated. The samples grown above
650°C are fully crystalline with perovskite structure. The film deposited at 700°C has columnar growth with electrical resistivity
of about 1.99×10 −3 Ω cm. The amorphous films grown at 500°C were post-annealed at different conditions. The sample post-annealed at 700°C and
10 −4 Pa has similar microstructure with the sample in situ grown at 700°C and 25 Pa. However, the electrical resistivity of the
post-annealed sample is one magnitude higher than that of the in situ grown sample because of the effect of oxygen vacancy.
The temperature dependence of resistivity exhibits semiconductor-like character. It was found that post-annealing by rapid
thermal process will result in film cracks due to the thermal stress. The results are referential for the applications of
LSCO in microelectronic devices. 相似文献
16.
The ions of Sb, As, and P have been implanted into germanium at energies ranging from 200 keV to 700 keV. Annealing was performed
at 400°C, 550°C, and 650°C. The doping profile was determined by differential CV-measurements. Strong outdiffusion (80%) and diffusion into the bulk material was observed after annealing. The remaining
doping concentration and the diffusion constants were determined by a computer fit at 650°C. We found D
Sb=1.8×10 −13 cm 2/s, D
As=9×10 −14 cm 2/s and D
P=4×10 −14 cm 2/s. Lower values of the diffusion constant were determined when the samples were covered with a SiO 2 layer. 相似文献
17.
HfLaO x based Metal–oxide–semiconductor capacitors were fabricated by atomic layer deposition in this work. The material and electrical properties of the films along with the high temperature thermal treatment were investigated. It was found that samples undergoing annealing at 900 °C exhibited the best performance. The film was found to be crystallized to a cubic structure at 900 °C, and the roughness of the films was estimated to be 0.332 nm. For electrical characterization, the C–V curve of the film is in good agreement with the corresponding simulated curve, and the capacitor does not show any hysteresis. Moreover, the Dit near the center of silicon band gap exhibits lowest value, and it was calculated to be 2.28 × 10 11 eV ?1 cm ?2. 相似文献
18.
Y 2SiO 5:Ce phosphor thin films were grown onto Si(100) substrates with pulsed laser deposition (PLD) using a 248-nm KrF excimer laser.
Process parameters were varied during the growth process and the effect on the surface morphology and cathodoluminescence
(CL) was analysed. The process parameters that were changed included the following: gas pressure (vacuum (5×10 −6 Torr), 1×1 −2 Torr and 1 Torr O 2), different gas species (O 2, Ar and N 2 at a pressure of 455 mTorr), laser fluence (1.6±0.1 J cm −2 and 3.0±0.3 J cm −2) and substrate temperature (400 and 600°C). The surface morphology was investigated with atomic force microscopy (AFM). The
morphology of the thin films ablated in vacuum and 10 mTorr ambient O 2 showed more or less the same trend. An increase in the pressure to 1 Torr O 2, however, showed a definite increase in deposited particle sizes. Ablation in N 2 gas resulted in small particles of 20 nm in diameter and ablation in O 2 gas produced bigger particles of 20, 30 and 40 nm as well as an agglomeration of these particles into bigger size clusters
of 80 to 100 nm. Ablation in Ar gas led to particle sizes of 30 nm and the particles were much more spherically defined and
evenly distributed on the surface. The higher fluence deposition led to bigger particle and grain sizes as well as thicker
layers with respect to the lower fluence. The particle sizes of the higher fluence vary mainly between 130 and 140 nm and
the lower fluence sizes vary between 50 and 60 nm. The higher fluence particles consist of smaller particles ranging from
5 to 30 nm as measured with AFM. The surface structure of the thin film ablated at 400°C substrate temperature is less compact
(lesser agglomeration of particles than at 600°C). The increase in substrate temperature definitely resulted in a rougher
surface layer. CL was measured to investigate the effect of the surface morphology on the luminescent intensities. The increased
O 2 ambient (1 Torr) resulted in a higher CL intensity compared to the thin films ablated in vacuum. The thin film ablated in
Ar gas showed a much higher CL intensity than the other thin films. Ablation at a high fluence resulted in a higher CL intensity.
The higher substrate temperature resulted in better CL intensities. The more spherically shaped particles and rougher surface
led to increase CL intensities. 相似文献
19.
Thin films of tin sulphide (SnS) have been grown by sulphurization of sputtered tin precursor layers in a closed chamber. The effect of sulphurization temperature (T s) that varied in the range of 150–450 °C for a fixed sulphurization time of 120 min on SnS film was studied through various characterization techniques. X-ray photoelectron spectroscopy analysis demonstrated the transformation of metallic tin layers into SnS single phase for T s between 300 °C and 350 °C. The X-ray diffraction measurements indicated that all the grown films had the (111) crystal plane as the preferred orientation and exhibited orthorhombic crystal structure. Raman analysis showed modes at 95 cm −1, 189 cm −1 and 218 cm −1 are related to the A g mode of SnS. AFM images revealed a granular change in the grain growth with the increase of T s. The optical energy band gap values were estimated using the transmittance spectra and found to be varied from 1.2 eV to 1.6 eV with T s. The Hall effect measurements showed that all the films were p-type conducting nature and the layers grown at 350 °C showed a low electrical resistivity of 64 Ω-cm, a net carrier concentration of 2 × 10 16 cm −3 and mobility of 41 cm 2 V −1 s −1. With the use of sprayed Zn 0.76Mg 0.24O as a buffer layer and the sputtered ZnO:Al as window layer, the SnS based thin film solar cell was developed that showed a conversion efficiency of 2.02%. 相似文献
20.
In 2O 3:Sn (Indium Tin Oxide; ITO) films were prepared from a sol solution with highly crystalline ITO nanoparticles (less than 20 nm in size with 10 at.% Sn) which had been prepared by low-pressure spray pyrolysis (LPSP) in a single step. The ITO sol solution was prepared by dispersing LPSP-prepared ITO nanoparticles into ultra pure water. The nanoparticle ITO film was deposited on a glass substrate using a dip-coating method and then annealed in air at various temperatures. The optical transmittances of the ITO films were measured by UV–Vis spectrometry, and the films were found to have a high transparency to visible light (in the case of a film thickness of 250 nm annealed at 400°C, the transparency was in excess of 95% over the range λ=450–800 nm, with a maximum value near 100% at wavelengths above λ=700 nm). The optical transmittances of the films were influenced by the size of the ITO particle used, the film thickness and the annealing temperature. The ITO films showed a minimum resistivity of 9.5×10 −2 Ω cm, and their resistivity was affected by both the ITO particle size and the annealing temperature used. 相似文献
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