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1.
Indium tin oxide (ITO) and titanium dioxide (TiO2) single layer and double layer ITO/TiO2 films were prepared using reactive pulsed laser ablation deposition (RPLAD) with an ArF excimer laser for applications in dye-sensitized solar cells (DSSCs). The films were deposited on SiO2 substrates either at room temperatures (RT) or heated to 200-400 °C. Under optimized conditions, transmission of ITO films in the visible (vis) range was above 89% for films produced at RT and 93% for the ones deposited at higher temperatures. Increasing the substrate temperature from RT to 400 °C enhances the transmission of TiO2 films in the vis-NIR from about 70% to 92%. High transmission (≈90%) was observed for the double layer ITO/TiO2 with a transmission cut-off above 900 nm. From the transmission data, the energies gaps (Eg), as well as the refractive indexes (n) for the films were estimated. n ≈ 2.03 and 2.04, respectively for ITO films and TiO2 film deposited at 400 °C in the visible region. Post-annealing of the TiO2 films for 3 h at 300 and 500 °C was performed to enhance n. The refractive index of the TiO2 films increases with the post-annealing temperature. The direct band gap is 3.6, 3.74 and 3.82 eV for ITO films deposited at RT, 200, and 400 °C, respectively. The TiO2 films present a direct band gap of 3.51 and 3.37 eV for as deposited TiO2 films and when annealed at 400 °C, respectively. There is a shift of about 0.1 eV between ITO and ITO/TiO2 films deposited at 200 °C. The shift decreases by half when the TiO2 film was deposited at 400 °C. Post-annealing was also performed on double layer ITO/TiO2. 相似文献
2.
TiO2 doped WO3 thin films were deposited onto glass substrates and fluorine doped tin oxide (FTO) coated conducting glass substrates, maintained at 500 °C by pyrolytic decomposition of adequate precursor solution. Equimolar ammonium tungstate ((NH4)2WO4) and titanyl acetyl acetonate (TiAcAc) solutions were mixed together at pH 9 in volume proportions and used as a precursor solution for the deposition of TiO2 doped WO3 thin films. Doping concentrations were varied between 4 and 38%. The effect of TiO2 doping concentration on structural, electrical and optical properties of TiO2 doped WO3 thin films were studied. Values of room temperature electrical resistivity, thermoelectric power and band gap energy (Eg) were estimated. The films with 38% TiO2 doping in WO3 exhibited lowest resistivity, n-type electrical conductivity and improved electrochromic performance among all the samples. The values of thermoelectric power (TEP) were in the range of 23-56 μV/K and the direct band gap energy varied between 2.72 and 2.86 eV. 相似文献
3.
O. Bethge C. Henkel S. AbermannG. Pozzovivo M. Stoeger-PollachW.S.M. Werner J. SmolinerE. Bertagnolli 《Applied Surface Science》2012,258(8):3444-3449
La2O3 grown by atomic layer deposition (ALD) and thermally grown GeO2 are used to establish effective electrical surface passivations on n-type (1 0 0)-Ge substrates for high-k ZrO2 dielectrics, grown by ALD at 250 °C substrate temperature. The electrical characterization of MOS capacitors indicates an impact of the Ge-surface passivation on the interfacial trap density and the frequency dependent capacitance in the inversion regime. Lower interface trap densities can be obtained for GeO2 based passivation even though a chemical decomposition of the oxidation states occur during the ALD of ZrO2. As a consequence the formation of a ZrGeOx compound inside the ZrO2 matrix and a decline of the interfacial GeO2 are observed. The La2O3 passivation provides a stable amorphous lanthanum germanate phase at the Ge interface but also traces of Zr germanate are indicated by X-ray-Photoelectron-Spectroscopy and Transmission-Electron-Microscopy. 相似文献
4.
Ajay Kaushal 《Physica B: Condensed Matter》2009,404(20):3732-3738
Sn1−xMnxO2 (x=0.01-0.05) thin films were synthesized on quartz substrate using an inexpensive ultrasonic spray pyrolysis technique. The influence of doping concentration and substrate temperature on structural and magnetic properties of Sn1−xMnxO2 thin films was systematically investigated. X-ray diffraction (XRD) studies of these films reflect that the Mn3+ ions have substituted Sn4+ ions without changing the tetragonal rutile structure of pure SnO2. A linear increase in c-axis lattice constant has been observed with corresponding increase in Mn concentration. No impurity phase was detected in XRD patterns even after doping 5 at% of Mn. A systematic change in magnetic behavior from ferromagnetic to paramagnetic was observed with increase in substrate temperature from 500 to 700 °C for Sn1−xMnxO2 (x=0.01) films. Magnetic studies reveal room-temperature ferromagnetism (RTFM) with 3.61×10−4 emu saturation magnetization and 92 Oe coercivity in case of Sn1−xMnxO2 (x=0.01) films deposited at 500 °C. However, paramagnetic behavior was observed for the films deposited at a higher substrate temperature of 700 °C. The presence of room-temperature ferromagnetism in these films was observed to have an intrinsic origin and could be obtained by controlling the substrate temperature and Mn doping concentration. 相似文献
5.
Yoji Akaki Kyohei Yamashita Tsuyoshi Yoshitake Shigeuki Nakamura Satoru Seto Takahiro Tokuda Kenji Yoshino 《Physica B: Condensed Matter》2012,407(15):2858-2860
We characterized AgInS2 thin films prepared by vacuum evaporation. In the case of thin films annealed at 400 °C, diffraction peaks were observed only for the chalcopyrite AgInS2 phase. The chemical composition of the thin films annealed at 400 °C was 26.5 at% Ag, 23.8 at% In, and 49.7 at% S. PL spectra of the AgInS2 thin films at 10.7 K showed peaks at 1.70, 1.80, and 1.83 eV. The PL peak at1.80 eV was attributed to sulfur deficiency. 相似文献
6.
Jing Yang 《Applied Surface Science》2006,253(4):1988-1994
To use solar irradiation or interior lighting efficiently, we sought a photocatalyst with high reactivity under visible light. Nitrogen and carbon doping TiO2−x−yNxCy films were obtained by heating the TiO2 gel in an ionized N2 gas and then were calcined at 500 °C. The TiO2−x−yNxCy films have revealed an improvement over the TiO2 films under visible light (wavelength, 500 nm) in optical absorption and photocatalytic activity such as photodegradation of methyl orange. X-ray photoemission spectroscopy, infrared spectrum and UV-visible (UV-vis) spectroscopy were used to find the difference of two kinds of films. Nitrogen and carbon doped into substitutional sites of TiO2 has been proven to be indispensable for band-gap narrowing and photocatalytic activity. 相似文献
7.
Hasan Efeog
lu Tevhit Karacali Kadem Meral brahim Y. Erdog
an Yavuz Onganer 《Journal of luminescence》2010,130(1):157-162
Photoluminescence (PL) of Al2O3 films obtained by anodization of thermally evaporated and annealed thin Al films on p++Si in 0.3 M oxalic acid has been investigated. Thermal annealing at 200–950 °C under the dry nitrogen atmosphere was used for deactivation of luminescence centres. Luminescence from as grown films was broad and located at 425 nm. This luminescence reached to highest level after annealing at 600 °C. Maximum 10 min was required for full optical activation and prolonged annealing up to 4 h did not change the luminescence intensity. Because of deep levels, absorption band edge of as grown films was shifted to the lower energy which is 3.25 eV. Annealing above 800 °C reduced the PL intensity and this observation was correlated with the blue shift of band edge as the defects annealed out. Disappearing PL intensity and blue shift of band edge absorption after annealing at 950 °C was mainly attributed to the oxygen-related defects and partly to impurities that may be originated from oxalic acid. AFM results did not show any hexagonally ordered holes but uniformly distributed nanosized Al2O3 clusters that were clearly seen. XRD measurements on as grown Al2O3 showed only [1 1 0] direction of α phase. Debye–Scherer calculation for this line indicates that cluster size is 35.7 nm. XRD and AFM pictures suggest that nanocrystalline Al2O3 are embedded in amorphous Al2O3. 相似文献
8.
Highly conducting films of p-type CuCrO2 are attractive as hole-injectors in oxide-based light emitters. In this paper, we report on the development of dry etch patterning of CuCrO2 thin films. The only plasma chemistry that provided some chemical enhancement was Cl2/Ar under inductively coupled plasma conditions. Etch rates of ∼500 Å min−1 were obtained at chuck voltages around −300 V and moderate source powers. In all cases, the etched surface morphologies were improved relative to un-etched control samples due to the smoothing effect of the physical component of the etching. The threshold ion energy for the onset of etching was determined to be 34 eV. Very low concentrations (≤1 at.%) of residual chlorine were detected on the etched surfaces but could be removed by simple water rinsing. 相似文献
9.
Zhenhai Liang Yongbo DingJinqian Jia Caimei FanPeide Han 《Physica B: Condensed Matter》2011,406(11):2266-2269
A theoretical study on Sb-doped SnO2 has been carried out by means of periodic density functional theory (DFT) at generalized gradient approximation (GGA) level. Stability and conductivity analyses were performed based on the formation energy and electronic structures. The results show that Sn0.5Sb0.5O2 solid solution is stable because the formation energy of Sn0.5Sb0.5O2 is −0.06 eV. The calculated energy band structure and density of states showed that the band gap of SnO2 narrowed due to the presence of the Sb impurity energy levels in the bottom of the conduction band, namely there is Sb 5s distribution of electronic states from the Fermi level to the bottom of conduction band after the doping of antimony. The studies provide a theoretical basis to the development and application of Sn1−xSbxO2 solid solution electrode. 相似文献
10.
Yanjie ZhangRuiqing Chu Zhijun XuQian Chen Yong LiuGuangchao Zhang 《Current Applied Physics》2012,12(1):204-209
(Bi0.5Na0.5)0.94Ba0.06TiO3 ceramics doped with Li2CO3 and Bi2O3 as sintering aids were manufactured, and their micro structural, dielectric and piezoelectric properties were investigated. All specimens could be well sintered at a low-temperature of 1080 °C. The bulk density of the specimens doped with a small amount of Li2CO3 was enhanced. The dielectric and piezoelectric properties of ceramics were investigated with different amounts of Li2CO3 substitutions. High electrical properties of d33 = 167 pC/N, kp = 0.34, Pr = 40 μC/cm2 and Ec = 38 kV/cm were obtained from the specimen containing 0.1 mol% of Li2CO3 sintered at 1080 °C. 相似文献
11.
ZnIn2Se4 is of polycrystalline structure in as synthesized condition. It transforms to nanocrystallite structure of ZnIn2Se4 film upon thermal evaporation. Annealing temperatures influenced crystallite size, dislocation density and internal strain. The hot probe test showed that ZnIn2Se4 thin films are n-type semiconductor. The dark electrical resistivity versus reciprocal temperature for planar structure of Au/ZnIn2Se4/Au showed existence of two operating conduction mechanisms depending on temperature. At temperatures >365 K, intrinsic conduction operates with activation energy of 0.837 eV. At temperatures <365 K, extrinsic conduction takes place with activation energy of 0.18 eV. The operating conduction mechanism in extrinsic region is variable range hopping. The parameters such as density of states at Fermi level, hopping distance and average hopping energy have been determined and it was found that they depend on film thickness. The dark current–voltage characteristics of Au/n-ZnIn2Se4/p-Si/Al diode at different temperatures ranging from 293–353 K have been investigated. Results showed rectification behavior. At forward bias potential <0.2 V, thermionic emission of electrons from ZnIn2Se4 film over a potential barrier of 0.28 V takes place. At forward bias potential >0.2 V, single trap space charge limited current is operating. The trap concentration and trap energy level have been determined as 3.12×1019 cm−3 and 0.24 eV, respectively. 相似文献
12.
P. Uday BhaskarG. Suresh Babu Y.B. Kishore KumarV. Sundara Raja 《Applied Surface Science》2011,257(20):8529-8534
Cu2SnSe3 is an important precursor material for the growth of Cu2ZnSnSe4, an emerging solar cell absorber layer via solid state reaction of Cu2SnSe3 and ZnSe. In this study, we have grown Cu2SnSe3 (CTSe) and Cu2SnSe3-ZnSe (20%) films onto soda-lime glass substrates held at 573 K by co-evaporation technique. The effect of annealing of these films at 723 K for an hour in selenium atmosphere is also investigated. XRD studies of as-deposited Cu2SnSe3 and Cu2SnSe3-ZnSe films indicated SnSe as secondary phase which disappeared on annealing. The direct optical band gap of annealed Cu2SnSe3 and Cu2SnSe3-ZnSe films were found to be 0.90 eV and 0.94 eV respectively. Raman spectroscopy studies were used to understand the effect of ZnSe on the properties of Cu2SnSe3. 相似文献
13.
Pb(Zr0.52Ti0.48)O3 (PZT) thin films with large remanent polarization and SrBi2Ta2O9 (SBT) thin films with excellent fatigue-resisting characteristic have been widely studied for non-volatile random access memories, respectively. To combine these two advantages, bilayered Pb(Zr0.52Ti0.48)O3/SrBi2Ta2O9 (PZT/SBT) thin films were fabricated on Pt/TiO2/SiO2/Si substrates by chemical solution deposition method. X-ray diffraction patterns revealed that the diffraction peaks of PZT/SBT thin films were completely composed of PZT and SBT, and no other secondary phase was observed. The electrical properties of the bilayered structure PZT/SBT films have been investigated in comparison with pure PZT and SBT films. PZT/SBT bilayered thin films showed larger remanent polarization (2Pr) of 18.37 μC/cm2 than pure SBT and less polarization fatigue up to 1 × 109 switching cycles than pure PZT. These results indicated that this bilayered structure of PZT/SBT is a promising material combination for ferroelectric memory applications. 相似文献
14.
The effects of nitrogen doping on the chemical bonding state, microstructure, electrical property and thermal stability of Ge15Sb85 film were investigated in detail. The doped N atoms tend to bond with Ge to form Ge3N4, as proved by X-ray photoelectron spectroscopy analyses. X-ray diffraction patterns showed that both undoped and N-doped Ge15Sb85 films crystallize into a hexagonal phase very similar to Sb. The thickness reduction upon crystallization for undoped and N-doped Ge15Sb85 films is less than 5%. The crystalline resistivity, crystallization temperature, and thermal stability of amorphous state all increase after nitrogen doping, while the grain size decreases. By adding 7.0 at.% N into the Ge15Sb85 film, the crystalline resistivity increases twelve times and the crystallization temperature increases about 50 °C. The maximum temperature for 10-year retention of amorphous Ge15Sb85 film is estimated to be 147 °C and that of N-doped films is even higher, which will promise better data retention of phase-change random access memory especially in the high-temperature application. 相似文献
15.
O. Matsumoto A. Tsukada H. Yamamoto T. Manabe M. Naito 《Physica C: Superconductivity and its Applications》2010,470(20):1029-1032
Recently we have achieved superconductivity in T′-RE2CuO4 (RE = Pr, Nd, Sm, Eu, and Gd), films by metal organic decomposition (MOD). In this article, we first report the cation off-stoichiometry effect, which aims at screening out the possibility of hole doping by cation deficiencies. We also investigated the structure and microstructure of superconducting T′-Nd2CuO4 films synthesized by MOD. This investigation aims at elucidating why MOD-grown Nd2CuO4 films become superconducting whereas our previous Nd2CuO4 films grown by molecular beam epitaxy were not superconducting. 相似文献
16.
Unintentionally doped and zinc-doped indium nitride (U-InN and InN:Zn) films were deposited on (0 0 0 1) sapphire substrates by radio-frequency reactive magnetron sputtering, and all samples were then treated by annealing to form In2O3 films. U-InN and InN:Zn films have similar photon absorption characteristics. The as-deposited U-InN and InN:Zn film show the absorption edge, ∼1.8-1.9 eV. After the annealing process at 500 °C for 20 min, the absorption coefficient at the visible range apparently decreases, and the absorption edge is about 3.5 eV. Two emission peaks at 3.342 eV (371 nm) and 3.238 eV (383 nm) in the 20 K photoluminescence (PL) spectrum of In2O3:Zn films were identified as the free-exciton (FE) or the near band-to-band (B-B) and conduction-band-to-acceptor (C-A) recombination, respectively. 相似文献
17.
Visible-light photocatalytic activity of nitrogen-doped TiO2 thin film prepared by pulsed laser deposition 总被引:1,自引:0,他引:1
Lei Zhao 《Applied Surface Science》2008,254(15):4620-4625
Nitrogen-doped titanium dioxide (TiO2−xNx) thin films have been prepared by pulse laser deposition on quartz glass substrates by ablated titanium dioxide (rutile) target in nitrogen atmosphere. The x value (nitrogen concentration) is 0.567 as determined by X-ray photoelectron spectroscopy measurements. UV-vis spectroscopy measurements revealed two characteristic deep levels located at 1.0 and 2.5 eV below the conduction band. The 1.0 eV level is attributable to the O vacancy state and the 2.5 eV level is introduced by N doping, which contributes to narrowing the band-gap by mixing with the O2p valence band. The enhanced degradation efficiency in a broad visible-light range was observed from the degradation of methylene blue and methylene orange by the TiO2−xNx film. 相似文献
18.
Physicochemical, surface and catalytic properties of pure and doped CuO/Fe2O3 system were investigated using X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), nitrogen adsorption at −196 °C and CO-oxidation by O2 at 80-220 °C using a static method. The dopants were Li2O (2.5 mol%) and CoO (2.5 and 5 mol%). The results revealed that the increase in precalcination temperature from 400 to 600 °C and Li2O-doping of CuO/Fe2O3 system enhanced CuFe2O4 formation. However, heating both pure and doped solids at 600 °C did not lead to complete conversion of reacting oxides into CuFe2O4. The promotion effect of Li2O dopant was attributed to dissolution of some of dopant ions in the lattices of CuO and Fe2O3 with subsequent increase in the mobility of reacting cations. CoO-doping led also to the formation of mixed ferrite CoxCu1−xFe2O4. The doping process of the system investigated decreased to a large extent the crystallite size of unreacted portion of Fe2O3 in mixed solids calcined at 600 °C. This process led to a significant increase in the SBET of the treated solids. Doping CuO/Fe2O3 system with either Li2O or CoO, followed by calcination at 400 and 600 °C decreased its catalytic activity in CO-oxidation by O2. However, the activation energy of the catalyzed reaction was not much affected by doping. 相似文献
19.
Novel Pd/InVO4-TiO2 thin films with visible light photocatalytic activity were synthesized from the Pd and InVO2 co-doped TiO2 sol via sol-gel method. The photocatalytic activities of Pd/InVO4-TiO2 thin films were investigated based on the oxidative decomposition of methyl orange in aqueous solution. The as-prepared samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and UV-vis absorption spectroscopy (UV-vis). The results indicate that the Pd/InVO4-TiO2 thin films are compact, uniform and consist of sphere nanoparticles with diameters about 80-100 nm. The UV-vis spectra show that the Pd/InVO4-TiO2 thin films extend the light absorption spectrum toward the visible region. XPS results reveal that doped Pd exist in the form of metallic palladium. The photocatalytic experiments demonstrate that Pd doping can effectively enhance the photocatalytic activities of InVO4-TiO2 thin films in decomposition of aqueous methyl orange under visible light irradiation. It has been confirmed that Pd/InVO4-TiO2 thin films could be excited by visible light (E < 3.2 eV) due to the existence of the Pd and InVO4 doped in the films. 相似文献
20.
Bi5GexSe95−x (30, 35, 40 and 45 at.%) thin films of thickness 200 nm were prepared on glass substrates by the thermal evaporation technique. The influence of composition and annealing temperature, on the structural and electrical properties of Bi5GexSe95−x films was investigated systematically using X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX). The XRD patterns showed that the as-prepared films were amorphous in nature with few tiny crystalline peaks of relatively low intensity for 30 and 45 at.% and the Bi5Ge40Se55 annealed film was polycrystalline. The chemical composition of the Bi5Ge30Se65 film has been checked using energy dispersive X-ray spectroscopy (EDX). The electrical conductivity was measured in the temperature range 300-430 K for the studied compositions. The effect of composition on the activation energy (ΔE) and the density of localized states at the Fermi level N(EF) were studied, moreover the electrical conductivity was found to increase with increasing the annealing temperature and the activation energy was found to decrease with increasing the annealing temperature. The results were discussed on the basis of amorphous-crystalline transformations. 相似文献