Structural and optical properties of ZnO films prepared by ion beam sputtering

Based on the ion beam sputtering deposition technology,ZnO thin films are deposited on the glass substrate.The four-factor and three-level L 9(34)orthogonal experiment is used to obtain the best technological parameters of the deposited ZnO thin films,which are the discharge voltage of 3.5 kV,the oxygen current capacity of 8 sccm,the coil current of 8 A and the distance between target and substrate of 140 mm.The purity of the deposited ZnO thin film is 85.77%,and it has good crystallization in orientation.The experimental results show that research and development of the ion beam sputtering source are advanced,and the ion beam sputtering deposition technology can be used to deposit the orientation preferred thin films with good performance.     

B掺杂ZnO纳米薄膜的结构和光学特性研究

采用脉冲磁控溅射法制备了B掺杂ZnO(ZnO:B)纳米薄膜,并用X射线衍射(XRD)、扫描电子显微镜(SEM)和紫外-可见-近红外分光光度计分别研究了薄膜的结构和光学特性。结果表明:ZnO:B为多晶纳米薄膜,具有六方钎锌矿结构,且薄膜沿着c轴取向择优生长;在可见光和近红外光谱区的透光性能良好,其中在可见光区的平均透光率大于84%,而在近红外区的透光率随着波长增加而逐渐降低至45%。运用逐点无约束最优化法分析计算了薄膜的光学常数,在可见光区,ZnO:B纳米薄膜的光学常数随波长的变化很小且数值基本恒定,折射率约为2.0,而在紫外区,光学常数随波长的变化显著。     

Structural,electrical and optical properties of N-doped ZnO films synthesized by SS-CVD

N-doped p-type ZnO films have been synthesized on α-Al₂O₃ (0 0 0 1) substrate by solid-source chemical vapor deposition using Zn(CH₃COO)₂·2H₂O as the precursor and CH₃COONH₄ as the nitrogen source. The properties for ZnO films are dependent greatly on the growth conditions. Results show that the best electrical properties of the p-type film, such as carrier density $\text{N=9.8×10}{}^{17}\text{cm}{}^{\mathrm{-3}}$, resistivity $\text{ρ=20}\text{Ω}\text{cm}$ and Hall mobility $\text{μ=0.97}\text{cm}{}^2\text{/}\text{V}\text{s}$, were induced at the substrate temperature of 500°C with a precursor temperature of 250°C and a nitrogen source of 150°C, under which the highest mixed orientation for (1 0 0) and (1 1 0) planes of films was also achieved. The p-type ZnO films possess a transmittance of about 90% in visible region and a band gap of about $\text{3.20}\text{eV}$ at room temperature.     

Structural and optical properties of CdTe-nanocrystals thin films grown by chemical synthesis

By mans of a chemical synthesis technique stoichiometric CdTe-nanocrystals thin films were prepared on glass substrates at 70 °C. First, Cd(OH)₂ films were deposited on glass substrates, then these films were immersed in a growing solution prepared by dissolution of Te in hydroxymethane sulfinic acid to obtain CdTe. The structural analysis indicates that CdTe thin films have a zinc-blende structure. The average nanocrystal size was 19.4 nm and the thickness of the films 170 nm. The Raman characterization shows the presence of the longitudinal optical mode and their second order mode, which indicates a good crystalline quality. The optical transmittance was less than 5% in the visible region (400–700 nm). The compositional characterization indicates that CdTe films grew with Te excess.     

Structural, electrical and optical properties of ZnO thin films deposited by sol-gel method

Thin films of intrinsic and Al-doped ZnO were prepared by the sol-gel technique associated with spin coating onto glass substrates. Zinc acetate dehydrate, ethanol and monoethanolamine were used as a starting material, solvent and stabiliser, respectively. Structural, electrical and optical characterizations of the films have been carried out. All films are polycrystalline with a hexagonal wurtzite structure with a preferential orientation according to the direction 〈0 0 2〉. The four-points technique was used to characterize thin films electrically. All films exhibit a transmittance above 80-90% along the visible range up to 650 nm and a sharp absorption onset about 375 nm corresponding to the fundamental absorption edge 3.3 eV. Intense UV photoluminescence is observed for undoped and 1% Al-doped ZnO films.     

Structural and optical properties of thin In2O3 films produced by autowave oxidation

Cubic-phase In₂O₃ films are produced by the autowave oxidation reaction. Electron microscopy and photoelectron spectroscopy of the atomic profiles show that the samples are homogeneous over the entire area and throughout the thickness, with the typical grain size being 20–40 nm. The optical and electrical properties are studied for In₂O₃ films fabricated at different pressures in the vacuum chamber. In the wave-length range from 400 to 1100 nm, the transparency of the films was higher than 85%; the resistivity of the films was 1.8 × 10^?2 Ω cm.     

ZnO薄膜的结构特征及光学性能评价

利用金属有机物化学气相沉积(MOCVD)方法在Al2O3(0001)衬底上生长ZnO薄膜,通过改变衬底温度及生长舱压力,得到了各种不同表面形貌的ZnO薄膜.扫描电镜(SEM)用来对样品的形貌进行观察,当衬底温度及生长舱压力分别为400℃,40Pa和450℃,8Pa时,得到了纳米管及纳米墙结构.利用X射线衍射谱(XRD)、透射光谱及光致发光谱对样品的结构及光学性能进行评价.实验结果证明对于较高的生长温度和较低的生长舱压力所生长的样品具有较好的结晶质量.     

制备工艺对ZnO薄膜的结构与光学性质的影响

利用射频磁控反应溅射技术生长出具有高度晶面(0002)取向的ZnO外延薄膜。通过AFM、XRD、吸收光谱和荧光光谱等测试手段,分别研究分析了不同衬底、不同溅射气氛和退火对ZnO薄膜结构及光学性质的影响。研究表明,在200℃低温生长的硅基ZnO薄膜具有几百纳米的氧化锌准六角结构外形;当氧氩比为4:1(质量流量比)时,吸收谱激子峰最佳;退火后,激子峰(363 nm)加强,同时出现了402 nm的本征氧空位紫光发射。     

Structural, optical and electrical properties of zinc oxide thin films deposited by a spray pyrolysis technique

Zinc oxide (ZnO) thin films were deposited on glass substrates by spray pyrolysis technique decomposition of zinc acetate dihydrate in an ethanol solution with 30 mL of deposition rate, the ZnO thin films were deposited at two different temperatures: 300 and 350 ℃. The substrates were heated using the solar cells method. The substrate was R217102 glass, whose size was 30 × 17.5 × 1 mm³. The films exhibit a hexagonal wurtzite structure with a strong (002) preferred orientation. The higher value of crystallite size is attained for sprayed films at 350 ℃, which is probably due to an improvement of the crystallinity of the films at this point. The average trans mittance of obtain films is about 90%-95%, as measured by a UV-vis analyzer. The band gap energy varies from 3.265 to 3.294 eV for the deposited ZnO thin film at 300 and 350 ℃, respectively. The electrical resistivity measured of our films are in the order 0.36 Ω·cm.     

Structural, electrical and optical properties of zinc oxide produced by oxidation of zinc thin films

We have investigated the effects of oxidation temperature on the physical properties of polycrystalline zinc oxide thin films. Zinc thin films are oxidized at different temperatures in air. We have found that increasing the oxidation temperature deteriorates the preferred c-axis orientation. Also, increasing the oxidation temperature enlarges the crystal size and increases the number of needle-shaped crystals on the surface of the ZnO samples. By increasing the oxidation temperature, more than zinc melting point, tensile stresses start to build up in the films. Also by increasing temperature, sheet resistance of the films decreases, while photoluminescence intensity ratio (green to orange) increases. Increasing the oxidation temperature reduces the transparency of the films, too. It is proposed that either an increase in the number of oxygen vacancies or a decrease in the volume of grain boundaries, is responsible for the observed behavior of the films at higher oxidation temperatures.     

Structural and optical properties of nanocrystalline lead sulfide thin films prepared by microwave-assisted chemical bath deposition

Nanocrystalline PbS thin films have been successfully deposited on glass substrate from lead nitrate (Pb²⁺ ions) and thiourea (S^2? ions) precursors using MACB technique. The effects of molar concentration (0.02, 0.05, 0.075 and 0.1 M) on the structure and microstructure evolution were studied using X-ray diffraction (XRD), scanning electron microscopy, and atomic force microscopy. The optical properties were investigated using UV–vis spectrophotometer. Crystal size values obtained from XRD were compared with these calculated using atomic force microscopy (AFM). The values of optical band gaps were found to decrease as the ion source molar concentration increase.     

Structural and optical properties of copper enriched ZnSe thin films prepared by closed space sublimation technique

Thin films of Zn_1?xCu_xSe (0.00≤x≤0.20) have been prepared by the closed space sublimation technique. Various structural and optical properties have been investigated through X-ray diffraction (XRD), atomic force microscopy (AFM), spectrophotometry, spectroscopic ellipsometry (SE) and Fourier transform infrared spectroscopy (FTIR). The effect of Cu concentration has been observed on the physical properties of Zn_1?xCu_xSe films for varying concentrations of copper. X-ray diffraction patterns show that the films are polycrystalline having preferential orientation along the (111) plane. Full width at half maximum (FWHM) values obtained by XRD show that FWHM decreases up to 10% copper concentration while an opposite trend has been observed beyond this concentration. RMS values calculated by AFM shows that the deposited films have smooth morphology; crystallinity improves with increasing Cu concentration and optimum results are shown with 10% Cu concentration. Various optical parameters i.e. absorption coefficient (α), extinction coefficient (k), reflectance (R), refractive index (n), optical conductivity (σ_op) and electrical conductivity (σ_el) have been determined using transmission spectra at different copper concentrations. From the reflection spectra it is observed that reflectance increases with the increase of copper concentration. The band gap energy has been determined using k spectra at various copper concentrations through spectroscopic ellipsometry. It is found that the band gap energy of the films decreases with the increase of copper concentration while dielectric constant increases. FTIR analysis revealed that the characteristic ZnSe bond stretching–vibrating mode occurs at 670.8 cm^?1.     

B掺ZnO薄膜的制备及其光学性能研究

利用溶胶-凝胶法(sol-gel)在玻璃和硅衬底上生长了B掺杂量分别为0 at％、0.5at％、1.0 at％、2.0 at％、3.0 at％、4.0 at％的ZnO薄膜.采用X射线衍射仪(X-ray diffraction,XRD)、扫描电子显微镜(scanning electron microscope,SEM)、紫外-可见(ultraviolet-visible,UV-Vis)分光光度计等测试手段对薄膜的结构、形貌和光学性能进行了表征.结果 表明:所制备的样品在2θ=34.4°左右出现了ZnO晶体的(002)衍射峰,说明制得的样品具有六方纤锌矿结构.并且(002)衍射峰的半高宽先变小后变大,这说明衍射峰的强度是先加强后减弱,证明其晶粒尺寸是先增大后减小.当B掺杂量为3.0 at％时,样品沿(002)方向择优取向生长最为明显,薄膜上的晶粒生长均匀、致密.B掺氧化锌(BZO)薄膜在可见光区的透过率随B3+的掺杂量的增加先增加后减小,并出现轻微蓝移的现象.当掺入B3+的量为3.0 at％时,薄膜结晶质量最好,表面最为均匀、致密,透过率达到90％.     

ZnO薄膜的结构与光学性能研究

采用sol-gel法在石英衬底上制备了ZnO薄膜,通过改变溶胶浓度、涂敷层数及退火温度,研究了ZnO薄膜的形貌、结构性能及光学性能。结果表明,薄膜具有六方纤锌矿结构,表面均匀致密,晶粒大小在25～35nm之间,Zn含量为0.8mol/L的溶胶经旋涂并在500℃下退火1h后可获得最高的可见光透射率,平均透射率约为94%。获得的ZnO薄膜的光学带隙在3.27～3.29eV之间。     

Growth-temperature-dependent optical and acetone detection properties of ZnO thin films

Zinc oxide (ZnO) thin films were prepared onto glass substrates at moderately low growth temperature by two-stage spray pyrolysis technique. The effects of growth temperature on structural, optical and acetone detection properties were investigated with X-ray diffractometry, a UV-visible spectrophotometer, photoluminescence (PL) spectroscopy and a homemade gas sensor testing unit, respectively. All the films are polycrystalline with a hexagonal wurtzite phase and exhibit a preferential orientation along [002] direction. The film crystallinity is gradually enhanced with an increase in growth temperature. The optical measurements show that all the films are physically highly transparent with a transmittance greater than 82% in the visible range. The band gap of the film is observed to exhibit a slight red shift with an increasing growth temperature. The PL studies on the films show UV/violet PL band at ～ 395 nm. Among all the films investigated, the film deposited at 250 ℃ demonstrates a maximum sensitivity of 13% towards 20 ppm of acetone vapors at 300 ℃ operating temperature.     

Semiconducting properties of aluminum-doped ZnO thin films grown by spray pyrolysis technique

Highly transparent and preferential c-axis oriented nanocrystalline undoped and Al doped zinc oxide(AZO) thin films have been deposited onto amorphous glass substrate by spray pyrolysis. The XRD studies reveal that AZO with a hexagonal(wurtzite) crystal structure having(002) preferred orientation is formed. The atomic force microscope(AFM) shows uniform surface topography. The optical band gap values of undoped and AZO thin films were changed from 3.34 to 3.35 eV. The band gap energy and photoluminescence are found to depend on the Al doping. Thermoelectric power measurement shows film having n-type in nature. Dielectric constant and loss(tan)were found to be frequency dependent. Interparticle interactions in the deposited films are studied by complex impendence spectroscopy.     

低温磁控溅射制备CdS薄膜的结构和光学特性

用磁控溅射的方法在透明导电氧化物衬底上制备了CdS薄膜,制备时的衬底温度为30~200℃.X射线衍射测试结果表明在这一条件下制备的CdS薄膜是六角纤锌矿的多晶结构.扫描电子显微镜结果显示薄膜具有较好的晶体质量,这一结论也和拉曼光谱、紫外-可见吸收光谱、光致发光光谱的结果一致.拉曼光谱显示CdS薄膜内部的压应力随着制备温度的提高而增大.     

Structural,optical and photocatalytic properties of MgO/ZnO nanocomposites prepared by a hydrothermal method

MgO/ZnO nanocomposites were synthesized by a hydrothermal method at 180 °C for 15 h. The XRD results showed that MgO phase occurred over the whole range of Mg concentration used. The MgO induced a growth of crystallite size of ZnO. The particle shape of ZnO altered from an agglomerated nanosheet to a hexagonal platelet when loading with MgO and MgO was shaped in small rod structures. The optical band gap was increased from 3.190 to 3.225 eV. The photocatalytic degradation depended upon the irradiation time and MgO loading contents. In this study, the 5 mol% MgO/ZnO nanocomposite exhibited the best photocatalytic degradation of 98.3% during irradiation by blacklight for 90 min.     

Structural and optical properties of silicon nanowires synthesized by Ag-assisted chemical etching

Metal-assisted chemical etching (MACE) of silicon in an aqueous solution of hydrofluoric acid and hydrogen peroxide is established for the fabrication of large-area uniform silicon nanowire (SiNW) arrays. The effect of the silver catalyst layer thickness on the morphology of the synthesized nanostructures and nanowires is investigated. Atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) reveal that the morphology of the fabricated silicon nanostructures remarkably depends on the catalyst layer thickness, and an optimum layer thickness is necessary for the fabrication of SiNWs. Also the effect of different etching times on the structural and optical properties of the fabricated SiNWs is investigated. FESEM showed a linear increment of the nanowire length and slight diameter changes through different etching times. The ultralow reflectance of SiNWs in the absorption region through the measurement of specular and diffuse reflectance showed that with increase in the etching time, the total reflectance remarkably decreases. A broadband visible photoluminescence (PL) emission from these wires was observed, and it could be stated that the silicon nanocrystals (SiNCs) are mostly responsible for the PL emission. The SiNC sizes were determined by an analytical model through a frequency shift in the Raman spectrum. The synthesized optically-active SiNWs could, therefore, be considered as a promising candidate for a new generation of nanoscale opto-electronic devices.     

Facile deposition of ZnO:Cu films: Structural and optical characterization

Sol–gel technology has been applied for preparation of ZnO:Cu films. The proposed facile approach allows obtaining a wide variety of copper doped zinc oxide systems, revealing different structural and optical behaviors. The work presents structural and optical studies depending on Cu concentration and thermal treatments in the range of 500–800 °C. The structural analysis is performed by X-Ray diffraction (XRD). It reveals that small Cu addition enhances the film crystallization. Increasing copper concentration results in deterioration of ZnO:Cu crystallization. XRD study manifests no Cu oxide phases in ZnO:Cu film structure for lower Cu additions. For a specific higher copper concentration, an appearance of a small fraction of copper oxide is detected. Vibrational properties have been characterized by FTIR spectroscopy. The effect of the copper introduction into ZnO reveals a slight change of optical properties compared to ZnO films for certain Cu ratios. ZnO:Cu films with higher copper contents manifest different optical behaviors with very high transparency in spectral visible range.