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1.
Ti 1−xV xO 2 solid solution film photoelectrodes were prepared by the dip-coating sol–gel method. X-ray diffraction and X-ray photoelectron spectroscopy were employed to ensure the formation of the solid solution and their composition. Obvious photoresponses were observed in the visible region for the solid solution film electrodes with x0.05 and the red shift of the photoresponse was enhanced with increasing x. Moreover, the solid solution film electrodes were found to be photoelectrochemically stable. However, the onset potential of photocurrent shifted positively with increasing x. Band model of the solid solution was suggested to explain the effects of the vanadium incorporation on the photoelectrochemical properties. 相似文献
2.
B-doped a-Si 1−xC x:H films for a window layer of Si thin film solar cells have been prepared by the Cat-CVD method. It is found that C is effectively incorporated into the films by using C 2H 2 as a C source gas, where an only little C incorporation is observed from CH 4 and C 2H 6 under similar deposition conditions. Using a-Si 1−xC x:H films grown from C 2H 2, heterojunction p–i–n solar cells have been prepared by the Cat-CVD method. The cell structure is (SnO 2 Asahi-U)/ZnO/a-Si 1−xC x:H(p)/a-Si:H(i)/μc-Si:H(n)/Al. The obtained conversion efficiency was 5.4%. 相似文献
3.
Transmission electron microscopy (TEM) studies of epitaxial YBa 2Cu 3O 7−x thin films and YBa 2Cu 3O 7/PrBa 2Cu 3O 7 superlattices are summarized. High-resolution imaging of cross-sections and plan views and energy-dispersive X-ray microanalysis and electron energy loss spectroscopy in the transmission electron microscope were the methods applied. In the first section results on YBa 2Cu 3O 7−x thin films With varying oxygen stoichiometry deposited onto SrTiO 3 are discussed. Then, YBa 2Cu 3O 7/PrBa 2Cu 3O 7 superlattices deposited onto SrTiO 3 and MgO are investigated. Finally, an interface analysis of high-quality YBa 2Cu 3O 7−x thin films deposited onto sapphire with yttrium-stabilized zirconia buffer layers is presented. 相似文献
4.
Doping and electrical characteristics of in-situ heavily B-doped Si 1−x−yGe xC y (0.22< x<0.6, 0< y<0.02) films epitaxially grown on Si(100) were investigated. The epitaxial growth was carried out at 550°C in a SiH 4–GeH 4–CH 3SiH 3–B 2H 6–H 2 gas mixture using an ultraclean hot-wall low-pressure chemical vapor deposition (LPCVD) system. It was found that the deposition rate increased with increasing GeH 4 partial pressure, and only at high GeH 4 partial pressure did it decrease with increasing B 2H 6 as well as CH 3SiH 3 partial pressures. With the B 2H 6 addition, the Ge and C fractions scarcely changed and the B concentration ( CB) increased proportionally. The C fraction increased proportionally with increasing CH 3SiH 3 partial pressures. These results can be explained by the modified Langmuir-type adsorption and reaction scheme. In B-doped Si 1−x−yGe xC y with y=0.0054 or below, the carrier concentration was nearly equal to CB up to approximately 2×10 20 cm −3 and was saturated at approximately 5×10 20 cm −3, regardless of the Ge fraction. The B-doped Si 1−x−yGe xC y with high Ge and C fractions contained some electrically inactive B even at the lower CB region. Resistivity measurements show that the existence of C in the film enhances alloy scattering. The discrepancy between the observed lattice constant and the calculated value at the higher Ge and C fraction suggests that the B and C atoms exist at the interstitial site more preferentially. 相似文献
5.
AgInSn xS 2−x ( x = 0–0.2) polycrystalline thin films were prepared by the spray pyrolysis technique. The samples were deposited on glass substrates at temperatures of 375 and 400 °C from alcoholic solutions comprising silver acetate, indium chloride, thiourea and tin chloride. All deposited films crystallized in the chalcopyrite structure of AgInS 2. A p-type conductivity was detected in the Sn-doped samples deposited at 375 °C, otherwise they are n-type. The optical properties of AgInSn xS 2−x ( x < 0.2) resemble those of chalcopyrite AgInS 2. Low-temperature PL measurements revealed that Sn occupying an S-site could be the responsible defect for the p-type conductivity observed in AgInSn xS 2−x ( x < 2) thin films. 相似文献
6.
Solid solutions of Bi 3(Nb 1−xTa x)O 7 ( x = 0.0, 0.3, 0.7, 1) were synthesized using solid state reaction method and their microwave dielectric properties were first reported. Pure phase of fluorite-type could be obtained after calcined at 700 °C (2 h) −1 between 0 ≤ x ≤ 1 and Bi 3(Nb 1−xTa x)O 7 ceramics could be well densified below 990 °C. As x increased from 0.0 to 1.0, saturated density of Bi 3(Nb 1−xTa x)O 7 ceramics increased from 8.2 to 9.1 g cm −3, microwave permittivity decreased from 95 to 65 while Qf values increasing from 230 to 560 GHz. Substitution of Ta for Nb modified temperature coefficient of resonant frequency τf from −113 ppm °C −1 of Bi 3NbO 7 to −70 ppm °C −1 of Bi 3TaO 7. Microwave permittivity, Qf values and τf values were found to correlate strongly with the structure parameters of fluorite solid solutions and the correlation between them was discussed in detail. Considering the low densified temperature and good microwave dielectric proprieties, solid solutions of Bi 3(Nb 1−xTa x)O 7 ceramics could be a good candidate for low temperature co-fired ceramics application. 相似文献
7.
(Ti, Al)N films have drawn much attention as alternatives for TiN coatings, which are oxidized easily in air above 500 °C. We have investigated the effect of Al content on the oxidation resistance of (Ti 1 − xAl x)N films prepared by r.f. reactive sputtering. (Ti1 − xAlxN films (O ≤ x ≤ 0.55) were deposited onto fused quartz substrates by r.f. reactive sputtering. Composite targets with five kinds of Al-to-Ti area ratio were used. The sputtering gas was Ar (purity, 5 N) and N2 (5 N). The flow rate of Ar and N2 gas was kept constant at 0.8 and 1.2 sccm, respectively, resulting in a sputtering pressure of 0.4 Pa. The r.f. power was 300 W for all experiments. Substrates were not intentionally heated during deposition. The deposited films (thickness, 300 nm) were annealed in air at 600 900 °C and then subjected to X-ray diffractometer and Auger depth profiling. The as-deposited (Ti1 − xAlx)N films had the same crystal structure as TiN (NaCl type). Al atoms seemed to substitute for Ti in lattice sites. The preferential orientation of the films changed with the Al content of the film, x. Oxide layers of the films grew during annealing and became thicker as the annealing temperature increased. The thickness of the oxide layer grown on the film surface decreased with increasing Al content in the film. For high Al content films an Al-rich oxide layer was grown on the surface, which seemed to prevent further oxidation. All of the films, however, were oxidized by 900 °C annealing, even if the Al content was increased up to 0.55. 相似文献
8.
Measurements of optical constants (absorption coefficient, refractive index, extinction coefficient, real and imaginary part of the dielectric constant) have been made on a-(Se 70Te 30) 100−x (Se 98Bi 2) x thin films (where x=0, 5, 10, 15 and 20) of thickness 2000 Å in the wavelength range 450–1000 nm. It is found that the optical bandgap decreases with the increase of Se 98Bi 2 concentration in the a-(Se 70Te 30) 100−x(Se 98Bi 2) x system. The value of refractive index ( n) decreases, while the extinction coefficient ( k) increases with increasing photon energy. The results are interpreted in terms of concentration of localized states varying effective Fermi level. 相似文献
9.
Nanocrystalline Ba 1−xSr xTiO 3 ( x=0, 0.2, 0.4, 0.6, 0.8 and 1.0) precursors were synthesized using the stearic acid gel method. After the precursors had been calcined at 600–950°C for 0.5–1 h, nanocrystalline powders with the cubic perovskite structure were obtained and these were made into thick films. The powder samples were characterized by differential thermal analysis, X-ray diffraction and transmission electron microscopy, and the thick film samples were characterized by scanning electron microscopy and X-ray diffraction. The humidity-sensitive properties of the nanocrystalline Ba 1−xSr xTiO 3 thick films were investigated. The results show that these nanocrystalline thick films possess higher humidity sensitivity and lower resistance than those of conventional materials. 相似文献
10.
High quality GaN epitaxial layers were obtained with Al xGa 1−xN buffer layers on 6H–SiC substrates. The low-pressure metalorganic chemical vapor deposition (LP-MOCVD) method was used. The 500 Å thick buffer layers of Al xGa 1−xN (0≤ x≤1) were deposited on SiC substrates at 1025°C. The FWHM of GaN (0004) X-ray curves are 2–3 arcmin, which vary with the Al content in Al xGa 1−xN buffer layers. An optimum Al content is found to be 0.18. The best GaN epitaxial film has the mobility and carrier concentration about 564 cm 2 V −1 s −1 and 1.6×10 17 cm −3 at 300 K. The splitting diffraction angle between GaN and Al xGa 1−xN were also analyzed from X-ray diffraction curves. 相似文献
11.
The mechanical properties like hardness, Hv and compressive strength, σ of Ni 1−xZn xFe 2O 4 ( x = 0.2, 0.3, 0.4 and 0.5) prepared by the non-conventional flash combustion and citrate-gel decomposition techniques are studied and reported. It is observed that there is an increase in hardness with zinc content as well as sintering temperature. The hardness in the order of 2.0–3.63 GPa and compressive strength in the order of 150–240 MPa are obtained for Ni–Zn ferrites prepared by these non-conventional techniques. The influence of density, porosity and microstructure on hardness and compressive strength of Ni–Zn ferrites with respect to sintering temperature was studied. 相似文献
12.
Gadolinium-doped, yttrium oxide thin films have been deposited on silicon (001) substrates by radio-frequency (RF) magnetron reactive sputtering that exhibit cathodoluminescence (CL) at ultraviolet frequencies. The maximum CL brightness occurred at λ314–315 nm characteristic of the 6P 3 / 2 → 8S ( λ = 314 nm) transition observed in Gd-doped, yttrium oxide powders. The radiative recombination takes place at the rare earth activator Gd 3+ site embedded in the Y 2O 3−δ host; the optical transition resides within the band gap of the Y 2O 3−δ host and the transition observed is characteristic of atomic gadolinium. A combinatorial approach to sputtering was used to deposit a film of variable composition from 1 to 23 at.% Gd in Y 2O 3−δ in order to rapidly discern the composition node of optimal CL brightness. A simulation was created for the purpose of predicting the film combinatorial composition for binary and ternary alloys prior to sputtering experiments in order to facilitate our combinatorial thin film synthesis technique. The model prediction varied from the real experimental composition profile by only 2.2 at.% Gd ± 1.6 at.% proving the predictor as a useful aide to complement combinatorial thin film experiments. A film of composition Y 1.56Gd 0.44O 3.25 (8.3 at.% Gd) yielded the maximum CL brightness. CL brightness increased continuously up to the 8.3 at.% Gd composition due to the increased number of activators present in the host. Beyond this composition the brightness drastically decreased. The oxygen composition in the combinatorial film was strongly dependent on the Gd composition; films were sub-stoichiometric δ > 0 below 6 at.% Gd and was over-stoichiometric δ < 0 beyond this composition. 相似文献
13.
In 2O 3 thin films have been prepared from commercially available pure In 2O 3 powders by high vacuum thermal evaporation (HVTE) and from indium iso-propoxide solutions by sol-gel techniques (SG). The films have been deposited on sapphire substrates provided with platinum interdigital sputtered electrodes. The as-deposited HVTE and SG films have been annealed at 500°C for 24 and 1 h, respectively. The film morphology, crystalline phase and chemical composition have been characterised by SEM, glancing angle XRD and XPS techniques. After annealing at 500°C the films’ microstructure turns from amorphous to crystalline with the development of highly crystalline cubic In 2O 3−x (JCPDS card 6-0416). XPS characterisation has revealed the formation of stoichiometric In 2O 3 (HVTE) and nearly stoichiometric In 2O 3−x (SG) after annealing. SEM characterisation has highlighted substantial morphological differences between the SG (highly porous microstructure) and HVTE (denser) films. All the films show the highest sensitivity to NO 2 gas (0.7–7 ppm concentration range), at 250°C working temperature. At this temperature and 0.7 ppm NO 2 the calculated sensitivities ( S= Rg/ Ra) yield S=10 and S=7 for SG and HVTE, respectively. No cross sensitivity have been found by exposing the In 2O 3 films to CO and CH 4. Negligible H 2O cross has resulted in the 40–80% relative humidity range, as well as to 1 ppm Cl 2 and 10 ppm NO. Only 1000 ppm C 2H 5OH has resulted to have a significant cross to the NO 2 response. 相似文献
14.
We report on epitaxial {1 0 0} K 1−xRb xTiOPO 4 waveguide films for the visible spectral range grown on KTiOPO 4 substrates by liquid phase epitaxy. Using the m-line technique a refractive index increase of Δ nx≈0.007 and Δ nz≈0.004 for TM and TE polarisation has been determined for a K 0.78Rb 0.22TiOPO 4 film. Optical transmission and nearfield distribution are comparable to conventional ion-exchanged waveguides. Typical attenuation of about 1 dB/cm for both TM and TE polarisation was obtained at λ=532 and 1064 nm. Energy-dispersive X-ray spectrometry reveals solid-solution films with graded rubidium composition profiles. X-ray rocking curve analyses confirm the epitaxial growth process and indicate perfect and relaxed K 1−xRb xTiOPO 4 films. Atomic force microscopy investigations reveal regular step structures with step heights Δ h<1.3 nm resulting in rms-roughness values of ≈0.4 nm. 相似文献
15.
The electronic structure of the ladder-chain compound Sr 14−xCa xCu 24O 41 is studied by ab initio calculations within the local density approximation. The effects of Ca substitution and structure modulation on electronic structure are discussed. It is found that 0.05 holes per copper atom are on the ladder layers for fully substituted compound, Ca 14Cu 24O 41. 相似文献
16.
We propose a new approach to fabrication of hydrogenated amorphous silicon carbide (a-Si 1−xC x:H) thin films for solar cells by the catalytic chemical vapor deposition (Cat-CVD) method using a carbon catalyzer, which is more stable than tungsten or tantalum. It was found that by using the carbon catalyzer, undoped and boron-doped a-Si 1−xC x:H films were easily obtained from a SiH 4, CH 4 and B 2H 6 mixture without any change in the catalyzer surface, even after deposition for longer than 30 h. 相似文献
17.
The effects of bismuth doping on the oxygen-ion diffusion in oxide-ion conductors La 2−xBi xMo 2O 9 ( x=0.05, 0.1, and 0.15) have been studied by both internal friction and dielectric relaxation techniques. Two internal friction peaks of relaxation type (P 1 and P 2 peak) were observed at a measurement frequency of 4 Hz around 380 and 430 K, respectively. As for the dielectric measurement, a prominent dielectric relaxation peak (P d) was found in all the Bi-doped samples around 700 K at a measurement frequency of 50 kHz, which actually consists of two sub-peaks (denoted as P d1 and P d2 peak). With increasing Bi-doping content, two peaks shift to higher temperature and decrease in height, while the activation energy of both peaks increases. The main reason was interpreted as the introduction of the lone-pair electrons of bismuth, which tends to block the diffusion of oxygen ion. 相似文献
18.
The Ba xSr 1−xTiO 3 (BST)/Pb 1−xLa xTiO 3 (PLT) composite thick films (20 μm) with 12 mol% amount of xPbO–(1 − x)B 2O 3 glass additives ( x = 0.2, 0.35, 0.5, 0.65 and 0.8) have been prepared by screen-printing the paste onto the alumina substrates with silver bottom electrode. X-ray diffraction (XRD), scanning electron microscope (SEM) and an impedance analyzer and an electrometer were used to analyze the phase structures, morphologies and dielectric and pyroelectric properties of the composite thick films, respectively. The wetting and infiltration of the liquid phase on the particles results in the densification of the composite thick films sintered at 750 °C. Nice porous structure formed in the composite thick films with xPbO–(1 − x)B 2O 3 glass as the PbO content ( x) is 0.5 ≥ x ≥ 0.35, while dense structure formed in these thick films as the PbO content ( x) is 0.8 ≥ x ≥ 0.65. The volatilization of the PbO in PLT and the interdiffusion between the PLT and the glass lead to the reduction of the c-axis of the PLT phase. The operating temperature range of our composite thick films is 0–200 °C. At room temperature (20 °C), the BST/PLT composite thick films with 0.35PbO–0.65B 2O 3 glass additives provided low heat capacity and good pyroelectric figure-of-merit because of their porous structure. The pyroelectric coefficient and figure-of-merit FD are 364 μC/(m 2 K) and 14.3 μPa −1/2, respectively. These good pyroelectric properties as well as being able to produce low-cost devices make this kind of thick films a promising candidate for high-performance pyroelectric applications. 相似文献
19.
The partial substitution of Zn 2+ for Ag + in Ag 4P 2O 7 leads to the formation of a wide glassy domain of composition [Ag 4P 2O 7] (1−y) [Zn 2P 2O 7] (y) with 0.20y0.87. The introduction of AgI in these materials results in a new series of glasses of formula [(Ag 4P 2O 7) (1−y) (Zn 2P 2O 7) (y)] (1−X) [AgI] (x), which domain for the composition y = 0.25 corresponds to 0 x 0.64. The structure as well as the thermal and electrical properties of these materials are compared with those of the [AgPO 3] (1−X) [AgI] (x) and [Ag 4P 2O 7] (1−x) [AgI] (x) glasses. 相似文献
20.
Highly oriented YNi xMn 1−xO 3 thin films on SrTiO 3 (100) substrates were achieved by using pulsed laser deposition for x = 0.33 and x = 0.50. We used a combination of X-ray diffraction, scanning electron microscopy, atomic force microscopy, and magnetic-property measurements. The magnetic transition temperatures ( Tc) of the as-grown films are higher than the corresponding bulk values (typically 85 K instead of 80 K, for x = 0.5, and 60 K instead of 50 K, for x = 0.33). Our magnetic measurements also suggest a spin-glass characteristic in the x = 0.33 films, while a cluster glasslike behavior is observed for the films with x = 0.5, which is quite different from that of the bulk samples. Finally, the influence of post-deposition heat treatment on the magnetic properties of the as-grown films is discussed. 相似文献
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