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1.
《Materials Chemistry and Physics》2007,101(2-3):285-290
Zinc oxide thin films have been obtained by pulsed laser ablation of a ZnO target in O2 ambient at a pressure of 0.13 Pa using a pulsed Nd:YAG laser. ZnO thin films deposited on Si (1 1 1) substrates were treated at annealing temperatures from 400 °C up to 800 °C after deposition. The structural and optical properties of deposited thin films have been characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, photoluminescence spectra, resistivity and IR absorption spectra. The results show that the obtained thin films possess good single crystalline with hexagonal structure at annealing temperature 600 °C. Two emission peaks have been observed in photoluminescence spectra. As the post-annealing temperature increase, the UV emission peaks at 368 nm is improved and the intensity of blue emission at 462 nm decreases, which corresponds to the increasing of the optical quality of ZnO film and the decreasing of Zn interstitial defect, respectively. The best optical quality for ZnO thin films emerge at post-annealing temperature 600 °C in our experiment. The measurement of resistivity also proves the decrease of defects of ZnO films. The IR absorption spectra of sample show the typical Zn–O bond bending vibration absorption at wavenumber 418 cm−1. 相似文献
2.
K. Drogowska Z. Tarnawski A. Brudnik E. Kusior M. Sokołowski K. Zakrzewska A. Reszka N.- T.H. Kim-Ngan A.G. Balogh 《Materials Research Bulletin》2012,47(2):296-301
Single-, bi- and tri-layered films of Ti–TiO2 system were deposited by d.c. pulsed magnetron sputtering from metallic Ti target in an inert Ar or reactive Ar + O2 atmosphere. The nominal thickness of each layer was 50 nm. The chemical composition and its depth profile were determined by Rutherford backscattering spectroscopy (RBS). Crystallographic structure was analysed by means of X-ray diffraction (XRD) at glancing incidence. X-ray reflectometry (XRR) was used as a complementary method for the film thickness and density evaluation. Modelling of the optical reflectivity spectra of Ti–TiO2 thin films deposited onto Si(1 1 1) substrates provided an independent estimate of the layer thickness. The combined analysis of RBS, XRR and reflectivity spectra indicated the real thickness of each layer less than 50 nm with TiO2 film density slightly lower than the corresponding bulk value. Scanning Electron Microscopy (SEM) cross-sectional images revealed the columnar growth of TiO2 layers. Thickness estimated directly from SEM studies was found to be in a good agreement with the results of RBS, XRR and reflectivity spectra. 相似文献
3.
In this work, we have presented a new route to produce pure ZnO and composite ZnO-CuO thin films. In the process we have started with pure ZnO thin films and ended up with CuO by doping Cu in various percentages, ranging from 0% to 100%. We have managed to attain crystal phases in all doping concentrations. All the produced thin films have been crystallized at the annealing temperatures of 600 and 700 °C for 6 h. The X-ray diffraction (XRD) spectra have been performed to see the formation of crystal phases of all pure ZnO and composite ZnO-CuO thin films. These give insight that the two crystal phases related to ZnO and CuO stayed together within the thin film matrices, which were produced in different doping concentrations, i.e. nZnO + mCuO (0 ≤ n, m ≤ 100%). The scanning electron microscopy (SEM) micrographs and UV–vis absorption spectra have also been taken to elucidate the structure and composition of the all films. 相似文献
4.
H+ ions with various fluences are implanted into x and z-cut KTP crystals to achieve KTP film. Post-implantation annealing under different temperature is imposed on the samples to induce layer splitting and surface morphology modification. Layer exfoliation is observed in freestanding z-cut samples. Layer splitting is obtained using bonding method in x-cut sample implanted with 117 keV H+ ions at ion fluence of 6 × 1016 ions/cm2. Optical microscopy, scanning electron microscope and atomic force microscopy are used to observe splitting phenomenon. Rutherford backscattering spectroscopy/channeling method is employed to measure lattice damage and to investigate the relationship between implantation-induced defects and layer splitting. 相似文献
5.
《Materials Research Bulletin》2006,41(11):2123-2129
The zinc oxide thin films on aluminum foil have been successfully prepared by sol–gel method with methyl glycol as solvent. The film was characterized by means of XRD, TG, UV–vis, SEM and AFM, which show that the ZnO/Al film is formed by a layer of ZnO nano-sized particles with average diameter of 52.2 nm. Under the initial concentration of 20 mg/L phenol solution (500 mL) and visible light irradiation time of 3 h, more than 40% of the initial phenol was totally mineralized using two pieces of ZnO/Al thin film as photocatalyst with an efficient irradiation area of 400 cm2. It is a promising visible light responded photocatalyst for the activation of O2 at room temperature to degrade organic pollutants. 相似文献
6.
Yang Li Yinzhu Zhang Haiping He Zhizhen Ye Jie Jiang Jianguo Lu Jingyun Huang 《Materials Research Bulletin》2012,47(9):2235-2238
Non-polar ZnO thin films were deposited on m-plane sapphire substrates by pulsed laser deposition at various temperatures from 300 to 700 °C. The effects of growth temperature on surface morphology, structural, electrical, and optical properties of the films were investigated. All the films exhibited unique m-plane orientation indicated by X-ray diffraction and transmission electron microscopy. Based on the scanning electron microscopy and atomic force microscopy, the obtained films had smooth and highly anisotropic surface, and the root mean square roughness was less than 10 nm above 500 °C. The maximum electron mobility was ~18 cm2/V s, with resistivity of ~0.26 Ω cm for the film grown at 700 °C. Room temperature photoluminescence of the m-plane films was also investigated. 相似文献
7.
X.Q. Wei J.Z. Huang M.Y. Zhang Y. Du B.Y. Man 《Materials Science and Engineering: B》2010,166(2):141-146
Highly oriented zinc oxide thin films have been grown on quartz, Si (1 1 1) and sapphire substrates by pulsed laser deposition (PLD). The effect of temperature and substrate parameter on structural and optical properties of ZnO thin films has been characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), optical transmission spectra and PL spectra. The experimental results show that the best crystalline thin films grown on different substrate with hexagonal wurtzite structure were achieved at growth temperature 400–500 °C. The growth temperature of ZnO thin film deposited on Si (1 1 1) substrate is lower than that of sapphire and quartz. The band gaps are increasing from 3.2 to 3.31 eV for ZnO thin film fabricated on quartz substrate at growth temperature from 100 to 600 °C. The crystalline quality and UV emission of ZnO thin film grown on sapphire substrate are significantly higher than those of other ZnO thin films grown on different substrates. 相似文献
8.
《Materials Letters》2007,61(8-9):1763-1766
ZnO films deposited on glass, quartz and Al on silicon mono-crystal Si (100) substrates by using the wire explosion technique were investigated by X-ray diffraction (XRD), UV–VIS spectroscopy, scanning electron (SEM) and atomic force microscopy (AFM) measurements. X-ray diffraction measurements have shown that ZnO films are mainly composed of (100), (002) and (101) orientation crystallites. The post-deposition thermal treatment at 600 °C temperature in air has shown that the composite of Zn/ZnO film was fully oxidized to ZnO film. The XRD spectra of the film deposited in oxygen atmosphere at room temperature present high intensity dominating peak at 2h = 36, 32° corresponding to the (101) ZnO diffraction peak. The small fraction of the film (7%) corresponds to the (002) peak intensity at 2h = 34, 42°. This result indicates the good crystal quality of the film and hexagonal wurtzite-type structure deposited by zinc wire explosion. The optical absorption spectra shows the bands at 374, 373 and 371 nm corresponding to deposition conditions. The SEM analysis shows that ZnO films presented different morphologies from fractal network to porous films depending on deposition conditions. AFM analysis revealed the grain size ranges from 50 nm to 500 nm. The nanoneedles up to 300 nm in length were found as typical structures in the film. It was demonstrated that the wire explosion technique is a feasible method to produce ZnO crystalline thin films and nanostructures. 相似文献
9.
Xin-liang Chen Fei Wang Xin-hua Geng De-kun Zhang Chang-chun Wei Xiao-dan Zhang Ying Zhao 《Materials Research Bulletin》2012,47(8):2008-2011
Natively textured surface aluminum doped zinc oxide (ZnO:Al) thin films were directly deposited via pulsed direct current (DC) reactive magnetron sputtering on glass substrates. During the reactive sputtering process, the oxygen gas flow rate was varied from 8.5 sccm to 11.0 sccm. The influences of oxygen flow rate on the structural, electrical and optical properties of naturally textured ZnO:Al TCO thin films with milky surface were investigated in detail. Gradual oxygen growth (GOG) technique was developed in the reactive sputtering process for textured ZnO:Al thin films. The light-scattering ability and optical transmittance of the natively textured ZnO:Al TCO thin films can be improved through gradual oxygen growth method while maintaining a low sheet resistance. Typical natively textured ZnO:Al TCO thin film with crater-like surface exhibits low sheet resistance (Rs ~ 4 Ω), high transmittance (Ta > 85%) in visible optical region and high haze value (12.1%). 相似文献
10.
E. György F. Sima I.N. Mihailescu T. Smausz B. Hopp D. Predoi L.E. Sima S.M. Petrescu 《Materials science & engineering. C, Materials for biological applications》2010,30(4):537-541
Matrix assisted pulsed laser evaporation (MAPLE) was used for growing urease thin films designed for bio-sensor applications in clinical diagnostics. The targets exposed to laser radiation were made from a frozen composite manufactured by dissolving biomaterials in distilled water. We used a UV KrF* (λ = 248 nm, τFWHM ? 30 ns, ν = 10 Hz) excimer source for multipulse laser irradiation of the frozen targets cooled with Peltier elements. The laser source was operated at an incident fluence of 0.4 J/cm2. Urease activity and kinetics were assayed by the Worthington method that monitors urea hydrolysis by coupling ammonia production to a glutamate dehydrogenase reaction. A decrease in absorbance was measured at 340 nm and correlated with the enzymatic activity of urease. We show that the urease films obtained by MAPLE techniques remain active up to three months after deposition. 相似文献
11.
Aluminum doped ZnO thin films (ZnO:Al) deposited on flexible substrates are suitable to be used as transparent conductive oxide (TCO) thin films in solar cells because of the excellent optical and electrical properties. TPT films are a kind of composite materials and are usually used as encapsulation material of solar panels. In this paper, ZnO:Al film was firstly deposited on transparent TPT substrate by RF magnetron sputtering. The structural, optical, and electrical properties of the film were investigated by X-ray diffractometry (XRD), scanning electron microscope (SEM), UV–visible spectrophotometer, as well as Hall Effect Measurement System. Results revealed that the obtained film had a hexagonal structure and a highly preferred orientation with the c-axis perpendicular to the substrate. Also, the film showed a high optical transmittance over 80% in the visible region and a resistivity of about 3.03 × 10? 1 Ω·cm. 相似文献
12.
《Materials Letters》2007,61(11-12):2460-2463
Ga-doped zinc oxide (ZnO:Ga) transparent conductive films with highly (002)-preferred orientation were deposited on glass substrates by DC reactive magnetron sputtering method in Ar + O2 ambience with different Ar/O2 ratios. The structural, electrical, and optical properties were investigated by X-ray diffraction, Hall measurement, and optical transmission spectroscopy. The resistivity and optical transmittance of the ZnO:Ga thin films are of the order of 10− 4 Ω cm and over 85%, respectively. The lowest electrical resistivity of the film is found to be about 3.58 × 10− 4 Ω cm. The influences of Ar/O2 gas ratios on the resistivity, Hall mobility, and carrier concentration were analyzed. 相似文献
13.
We have investigated the effect of the deposition of an HfO2 thin film as a gate insulator with different O2/(Ar + O2) gas ratios using RF magnetron sputtering. The HfO2 thin film affected the device performance of amorphous indium–gallium–zinc oxide transistors. The performance of the fabricated transistors improved monotonously with increasing O2/(Ar + O2) gas ratio: at a ratio of 0.35, the field effect mobility of the amorphous InGaZnO thin film transistors was improved to 7.54 cm2/(V s). Compared to those prepared with an O2/(Ar + O2) gas ratio of 0.05, the field effect mobility of the amorphous InGaZnO thin film transistors was increased to 1.64 cm2/(V s) at a ratio of 0.35. This enhancement in the field effect mobility was attributed to the reduction of the root mean square roughness of the gate insulator layer, which might result from the trap states and surface scattering of the gate insulator layer at the lower O2/(Ar + O2) gas ratio. 相似文献
14.
《Materials Research Bulletin》2013,48(4):1397-1402
0-3 type ZnO/Bi3.6Eu0.4Ti3O12 (BEuT) nanocomposite films with ZnO nanopowders in BEuT host were prepared by chemical solution deposition. The effects of ZnO content on the structure, photoluminescence, and electrical properties of the films were investigated. The ZnO/BEuT molar ratio strongly affected the grain size and growth orientation of BEuT, dielectric and ferroelectric properties, as well as emission intensity. The nanocomposite films showed strong red emission peaks due to 5D0 → 7F1 and 5D0 → 7F2 transitions of Eu3+ ions. Good electrical properties with high dielectric constant of 480 (at 1 kHz) and large remanent polarization (2Pr) of 32 μC/cm2 were obtained for the nanocomposite films having a ZnO/BEuT molar ratio of 1:2. The mechanisms for enhanced photoluminescence and electric properties were discussed. The results suggest that the nanocomposite thin films are promising candidate materials for multifunctional optoelectronic devices. 相似文献
15.
《Materials Letters》2007,61(4-5):937-941
The (Pb, La)TiO3 (PLT) ferroelectric thin films with and without a special buffer layer of PbOx have been deposited on Pt/Ti/SiO2/Si(100) substrates by RF magnetron sputtering technique at room temperature. The microstructure and the surface morphology of the films annealed at 600 °C for 1 h have been investigated by X-ray diffraction (XRD) and atomic force microscope (AFM). The surface roughness of the PLT thin film with a special buffer layer was 4.45 nm (5 μm × 5 μm) in comparison to that of 31.6 nm (5 μm × 5 μm) of the PLT thin film without a special buffer layer. Ferroelectric properties such as polarization hysteresis loop (P–V loop) and capacitance–voltage curve (C–V curve) of the films were investigated. The remanent polarization (Pr) and the coercive field (Ec) are 21 μC/cm2 and 130 kV/cm respectively, and the pyroelectric coefficient is 2.75 × 10− 8 C/cm2 K for the PLT film with a special buffer layer. The results indicate that the (Pb, La)TiO3 ferroelectric thin films with excellent ferroelectric properties can be deposited by RF magnetron sputtering with a special buffer layer. 相似文献
16.
Spectroscopic ellipsometry (SE) was employed to realize in-situ monitoring and the determination of thermo-optic coefficients (TOC) of thin films by integrating a temperature controlled hot stage to the ellipsometer and applying the empirical relationship of Cauchy between the refractive index and wavelength in the data analysis. Magnetron sputtered titanium oxide thin films of 350 nm thick both as-deposited and post-deposition annealed were prepared on silicon wafers for this investigation. Results of ellipsometric analysis show that as-deposited TiO2 films have a negative TOC of ? 1.21 × 10? 4 K? 1 at 630 nm over the test temperature range 304–378 K. The post-deposition annealing at 923 K for 2 hours leads an increase in film refractive index to 2.29 from 2.17 for as-deposited TiO2 films, and an enhancement in TOC up to ? 2.14 × 10? 4 K? 1. X-ray diffraction (XRD) and scanning electron microscopy (SEM) cross-sectional analysis were performed for film structure characterization. 相似文献
17.
Pulsed laser deposition technique is used to fabricate thin films of MgFe2O4 on sapphire substrate. X-ray diffraction patterns show that films are epitaxial along (???) direction on c-axis oriented sapphire. The observation of six fold symmetry in phi scan for the film suggests the presence of twinned in-plane alignments. The presence of magnetic hysteresis loop at room temperature indicates the ferromagnetic behavior of the film. The coercive field of 742 Oe and remnant magnetization of 151 emu/cm2 is observed at room temperature. The coercive field and remnant magnetization decrease with increase in temperature. 相似文献
18.
S. Gowrishankar L. Balakrishnan T. Balasubramanian N. Gopalakrishnan 《Materials Science and Engineering: B》2013,178(1):31-38
Ga doped ZnO (GZO) and GaP codoped ZnO (GPZO) thin films of different concentrations (1–4 mol%) have been grown on sapphire substrates by RF sputtering for the fabrication of ZnO homojunction. The grown films have been characterized by X-ray diffraction (XRD), photoluminescence (PL), Hall measurement, energy dispersive spectroscopy (EDS), time-of-flight secondary ion mass spectrometer (ToF-SIMS), UV–Vis–NIR spectroscopy and atomic force microscopy (AFM). Unlike in conventional codoping, here we directly doped (codoped) GaP into ZnO to realize p-ZnO. The Hall measurements indicate that 2 and 4% GPZO films exhibit p-conductivity due to the sufficient amount of phosphorous incorporation while all the monodoped GZO films showed n-conductivity as expected. Among the p-ZnO films, 2% GPZO film shows low resistivity (2.17 Ωcm) and high hole concentration (1.8 × 1018 cm?3) by optimum incorporation of phosphorous due to best codoping. Similarly, among the n-type films, 2% GZO shows low resistivity (1.32 Ωcm) and high electron concentration (2.02 × 1019 cm?3) by optimum amount of Ga incorporation. The blue shift and red shift in NBE emission observed from PL acknowledged the formation of n- and p-conduction in monodoped and codoped films, respectively. The neutral acceptor bound exciton recombination (A0X) observed by low temperature PL for 2% GPZO confirms the p-conductivity. Further, the high concentration of P atoms than Ga observed from ToF-SIMS (2% GPZO) also supports the p-conductivity of the films. The fabricated p–n junction with best codoped p-(ZnO)0.98(GaP)0.02 and best monodoped n-Zn0.98Ga0.02O films showed typical rectification behavior of a diode. The diode parameters have also been estimated for the fabricated homojunction. 相似文献
19.
A qualitative study on adhesion of the oral bacteria Porphyromonas gingivalis on titanium (Ti), titanium nitride (TiN), fluorine modified hydroxyapatite (FHA) and zinc modified FHA (Zn-FHA) thin films is investigated. Ti and TiN thin films were deposited by DC magnetron sputtering and hydroxyapatite-based films were prepared by solgel method. The crystalline structure, optical characteristics, chemical composition and surface topography of the films were studied by XRD, optical transmission, XPS, EDAX and AFM measurements. The predominant crystallite orientation in the Ti and TiN films was along (002) and (111) of hcp and cubic structures, respectively. The Ti : O : N composition ratio in the surface of the Ti and TiN films was found to be 7 : 21 : 1 and 3 : 8 : 2, respectively. The atomic concentration ratio (Zn + Ca) / P in Zn-FHA film was found to be 1.74 whereby the Zn replaced 3.2% of Ca. The rough surface feature in modified HA films was clearly observed in the SEM images and the surface roughness (rms) of Ti and TiN films was 2.49 and 3.5 nm, respectively, as observed using AFM. The film samples were sterilized, treated in the bacteria culture medium, processed and analyzed using SEM. Surface roughness of the films was found to have least influence on the bacterial adhesion. More bacteria were observed on the TiN film with oxide nitride surface layer and less number of adhered bacteria was noticed on the Ti film with native surface oxide layer and on Zn-FHA film. 相似文献
20.
《Optical Materials》2014,36(12):2329-2331
Neodymium-doped lutetium fluoride (Nd3+:LuF3) thin films were successfully grown on MgF2 (0 0 1) substrates by pulsed laser deposition (PLD). It is void of cracks that are otherwise prevalent due to structural phase transitions in Nd3+:LuF3 during thin film deposition and bulk crystal growth. Cathodoluminescence (CL) spectra revealed multiple emission peaks, with a dominant peak in the vacuum ultraviolet (VUV) region at 179 nm. This peak has a decay time of 6.7 ns. The ability to grow high quality Nd3+-doped fluoride thin films would enable fabrication of VUV light-emitting devices that will enhance applications requiring efficient VUV light sources. 相似文献