Influence of thermal annealing on the composition and structural parameters of DC magnetron sputtered titanium dioxide thin films

Titanium dioxide films have been deposited using DC magnetron sputtering technique. Films were deposited onto RCA cleaned p‐silicon substrates at the ambient temperature at an oxygen partial pressure of 7 × 10^–5 mbar and sputtering pressure of 1 × 10 ^–3 mbar. The deposited films were annealed in the temperature range 673–873 K. The structure and composition of the films were confirmed using X‐ray diffraction and Auger electron spectroscopy. The structure of the films deposited at the ambient was found to be amorphous and the films annealed at 673 K and above were crystalline with anatase structure. The lattice constants, grain size, microstrain and the dislocation density of the film are calculated and correlated with annealing temperature.     

Effect of calcination on the crystallinity of sputtered TiO2 thin films as studied by Raman scattering

Titanium dioxide films have been deposited using DC magnetron sputtering technique onto silicon substrates at an ambient temperature and at an oxygen partial pressure of 7 × 10 ^–5 mbar and sputtering pressure (Ar + O₂) of 1 × 10 ^–3 mbar. The deposited films were calcinated at 673 and 773 K. The composition of the films as analyzed using Auger Electron Spectroscopy (AES) revealed the stoichiometry with an O and Ti ratio of 2.08. The influence of post‐deposition calcination on the Raman scattering of the films was studied. The existence of Raman active modes A_1g, B_1g and E_g corresponding to the Raman shifts are reported in this paper. The improvement of crystallinity of the TiO₂ films as shown by the Raman scattering studies has also been reported. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Studies on zirconium nitride films deposited by reactive magnetron sputtering

This paper deals with the preparation of Zirconium Nitride films by DC reactive magnetron sputtering. Films were deposited on silicon substrates at room temperature. Nitrogen partial pressure was varied from 4 × 10⁻⁵ to 10 × 10⁻⁵ m bar and the effect on the structural, electrical, optical properties of the films was systematically studied. The films formed at a nitrogen pressure of 6 × 10⁻⁵ mbar showed low electrical resistivity of 1.726 × 10⁻³ Ω.cm. The deposited films were found to be crystalline with refractive index and extinction coefficient 1.95 and 0.4352 respectively. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Spectroscopic ellipsometry studies of reactively sputtered nitrogen-rich GaAsN films

Nitrogen-rich GaAsN thin films have been deposited at 500 °C by reactive rf sputtering of GaAs target in argon-nitrogen atmosphere. The arsenic content of the films was varied by changing the nitrogen percentage in the sputtering atmosphere and the As/Ga ratio in the films was estimated by X-ray fluorescence measurements. Spectroscopic ellipsometry measurements have been carried out on these films and the measured ellispometric spectra were fitted with theoretical spectra generated by using suitable model sample structures. From the best fit parameters of the dispersion model, band-gap values and variation of refractive index and extinction coefficient as a function of wavelength have been obtained for films deposited with different percentages of nitrogen in the sputtering atmosphere. The films deposited with 12% to 100% nitrogen in the sputtering atmosphere, which are of hexagonal GaN, exhibit GaN-like optical properties, though effects due to excess arsenic in amorphous phase are seen in the films deposited with less than 40% nitrogen. The films deposited with 5% to 12% nitrogen in sputtering atmosphere are dominantly polycrystalline GaAs_xN_1−x (x ≈ 0.01 to 0.08) and exhibit variations in optical parameters, which are consistent with their structure and composition. The films deposited with less than 5% nitrogen in sputtering atmosphere are arsenic-rich and amorphous.     

Optical band gap of zinc nitride films prepared by reactive rf magnetron sputtering

Polycrystalline Zn₃N₂ films are prepared on Si and quartz glass substrates by RF magnetron sputtering at room temperature. The structural and optical properties are studied by X‐ray diffraction and double beam spectrophotometer, respectively. X‐ray diffraction indicates that the Zn₃N₂ films deposited on Si and quartz glass substrates both have a preferred orientation in (321) and (442), also are cubic in structure with the lattice constant a=0.9847 and 0.9783 nm, respectively. The absorption coefficients as well as the film thickness are calculated from the transmission spectra, and their dependence on photon energy is examined to determine the optical band gap. Zn₃N₂ is determined to be an indirect‐gap semiconductor with the band gap of 2.11(2) eV. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Optical characterization of sputtered amorphous aluminum nitride thin films by spectroscopic ellipsometry

We have measured and analyzed the optical constants and polarized optical properties of amorphous aluminum nitride (a-AlN) thin films deposited by RF reactive magnetron sputtering onto silicon(1 1 1) and glass substrates. The optical constants were obtained by analysis of the measured ellipsometric spectra in the wavelength range 300–1400 nm, using the Cauchy–Urbach model. Refractive indices and extinction coefficients of the films were determined to be in the range 1.80–2.11 and 8.6 × 10⁻³–1.5 × 10⁻⁵, respectively. Analysis of the absorption coefficient, in the wavelength range 200–1400 nm, shows the bandgap of a-AlN thin films to be 5.84 ± 0.05 eV. From the angle dependence of the p-polarized reflectivity we deduce a Brewster angle of 61° and a principal angle of 64°. Measurement of the polarized optical properties reveals a high transmissivity and very low absorptivity for a-AlN films in the visible and near infrared regions. X-ray diffraction analysis confirmed the amorphous nature of the films under study.     

直流反应磁控溅射法制备二氧化钛薄膜的光响应

采用直流反应磁控溅射的方法在镀有ITO的导电玻璃衬底上沉积了二氧化钛薄膜,分别用拉曼光谱和吸收光谱研究了薄膜的结构,通过光电流研究了二氧化钛薄膜的紫外光响应。在100s的时间内光电流能达到最大值的96％,当停止紫外光照射时,光电流在200s的时间内能恢复到暗电流,二氧化钛薄膜对紫外光的灵敏性和稳定的光响应表明二氧化钛薄膜有可能成为一种新的紫外光探测器材料。     

射频磁控溅射制备纳米TiO2薄膜的表征和亲水性能

采用射频磁控溅射TiO2陶瓷靶的方法在硅和石英衬底上制备纳米TiO2薄膜,并经950℃退火1h.通过X射线衍射(XRD)、原子力显微镜(AFM)、紫外可见光谱(UV-Vis)和接触角仪对薄膜相结构、表面形貌、光学性能和亲水性能进行表征.结果表明,与950℃退火1h相比,未退火薄膜是无定形结构并呈现较高的光致亲水性能.退火薄膜是锐钛矿和金红石混合相,其中锐钛矿相质量分数是11.34％.未退火和950℃退火1h的薄膜样品的能隙分别是3.03 eV和3.11 eV.未退火薄膜具有较高的光致亲水性能主要归因于其较低的光学能隙.退火薄膜的热致亲水性能与其相结构、表面清洁度和粗糙度有关.     

Investigation of DTS effect on r.f. magnetron sputtered ZnO thin films

The aim of this study depends on understanding the effect of target‐to‐substrate distance (D_TS) on ZnO thin films deposited by r.f. magnetron sputtering on to glass substrates at room temperature conditions. The D_TS was changed from 35 mm to 65 mm with steps of 5 mm at 165 W and 0.2 Pa. The deposition rate of the films were ranged from 76 Ǻ / min to 146 Ǻ / min, while 10^‐3 Ω.cm was obtained as the resistivity value with the help of four point probe technique. The structural investigations were carried out by using both the x‐ray diffraction (XRD) and high resolution transmission electron microscopy. According to XRD observations, the films were (002) oriented. Surface behaviour of the ZnO films was examined with atomic force microscopy and scanning electron microscopy. The root mean square (RMS) values were varied from 4.6 nm to 22.8 nm. Also, optical properties were obtained from UV–visible spectrophotometer and the transmittances as around 80 %. At 45 mm D_TS value, the minimum resistivity measured as 9 × 10^{− 4} Ω.cm with 76 Ǻ / min deposition rate. The RMS was obtained as 4.9 nm and transmission was measured as 85.30 %, while band gap was 3.45 eV.     

衬底温度对直流反应磁控溅射法制备的N掺杂p型ZnO薄膜性能的影响

利用直流反应磁控溅射法(纯金属锌作为靶材,Ar-N2-O2混合气体作为溅射气体)在石英玻璃衬底上制备了N掺杂p型ZnO薄膜.通过XRD、Hall和紫外可见透射谱分别研究了衬底温度对ZnO薄膜结构性能、电学性能和光学性能的影响.XRD结果显示所有制备的薄膜都具有垂直于衬底的c轴择优取向,并且随着衬底温度的增加,薄膜的晶体质量得到了提高.Hall测试表明衬底温度对p型ZnO薄膜的电阻率具有较大影响,400℃下生长的p型ZnO薄膜由于具有较高的迁移率(1.32 cm2/Vs)和载流子浓度(5.58×1017cm-3),因此表现出了最小的电阻率(8.44Ω·cm).     

Heat treatment induced structural and optical properties of rf magnetron sputtered tantalum oxide films

Rf magnetron sputtering technique was employed for preparation of tantalum oxide films on quartz and crystalline silicon (111) substrates held at room temperature by sputtering of tantalum in an oxygen partial pressure of 1x10^‐4 mbar. The films were annealed in air for an hour in the temperature range 573 – 993 K. The effect of annealing on the chemical binding configuration, structure and optical absorption of tantalum oxide films was systematically studied. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Effect of annealing on the structural,electrical and optical properties of nanostructured TiO2 thin films

Nanostructured titanium dioxide thin films were prepared using reactive pulsed laser ablation technique. Effects of annealing on the structural, morphological, electrical and optical properties are discussed. The structural, electrical and optical properties of TiO₂ films are found to be sensitive to annealing temperature and are described with GIXRD, SEM, AFM, UV‐Visible spectroscopy and electrical studies. X‐ray diffraction studies showed that the as‐deposited films were amorphous and at first changed to anatase and then to rutile phase with increase of annealing temperature. Optical constants of these films were derived from the transmission spectra and the refractive index dispersion of the films, subjected to annealing at different temperatures, is discussed in terms of the single oscillator‐Wemple and Didomenico model. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Optical and opto‐electronic properties of polycrystalline Cd0.96Zn0.04Te thin films

Cd_0.96Zn_0.04Te thin films are deposited onto thoroughly cleaned glass substrates (Corning 7059) kept at room temperature by vacuum evaporation. The films are found to have good stoichiometry as analyzed by Rutherford Backscattering Spectrometry. The films exhibited zinc blende structure with predominant (111) orientation. The surface morphology of the films is studied by Atomic Force Microscopy. The rms roughness of the films evaluated by AFM is 3.7 nm. The pseudodielectric‐function spectra, ε(E) = ε₁(E) + i ε₂(E) at room temperature are measured by spectroscopic ellipsometry. The measured dielectric function spectra reveal distinct structures at energies of the E₁, E₁+ Δ₁ and E₂ critical points. The band gap energy of the films measured by optical transmittance measurement is 1.523 eV. The PL spectrum of the films shows intense emission due to free and bound exciton recombination and no emission associated with crystal imperfection and deeper impurity levels. The PL line shapes give indications of the high quality of the layers.     

Characterization of reactive DC magnetron sputtered TiAlN thin films

Thin films of about 1μm Titanium Aluminum Nitride (TiAlN) were deposited onto mild steel substrates by reactive direct current (DC) magnetron sputtering using a target consisting of equal segments of titanium and aluminum. X‐ray diffraction (XRD) analysis showed that the TiAlN phase had preferred orientations along 111 and 200 with the face‐centered cubic structure. Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM) analyses indicated that the films were uniform and compact. Photoluminescence (PL) spectra reveal that TiAlN thin films are of good optical quality. Laser Raman studies revealed the presence of characteristic peaks of TiAlN at 312.5, 675, and 1187.5 cm^–1. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

射频反应磁控溅射制备ZnO薄膜的微结构及其光学性能

采用射频反应磁控溅射技术在石英和Si衬底上制备了高度c轴择优取向的ZnO薄膜,样品的氧氩流量比分别为10:40,20:40,30:40,40:40.利用X射线衍射仪、表面轮廓仪、原子力显微镜和紫外-可见分光光度计研究了样品的微结构与光学特性.研究表明:氧氩流量比为30:40的样品结晶质量最好.所制备的ZnO薄膜的可见光平均透射率均大于87;.随着氧氩流量比的增大,薄膜的透射率呈非单调变化,氧氩流量比为30:40的样品在可见光范围的平均透射率可达93;.光学带隙随着氧氩流量比的增大,先增大后减小.与块材ZnO的带隙(3.37 eV)相比,ZnO薄膜的带隙均变窄.     

Structure and Optical Properties of dc Reactive Magnetron Sputtered Zinc Oxide Films

Zinc oxide films were deposited on glass substrates in argon and oxygen atmosphere by dc reactive magnetron sputtering using a metallic zinc target. The influence of oxygen pressure and substrate temperature on the structure and optical properties of the films were systematically investigated and optimised the deposition parameters to prepare single phase zinc oxide films with preferred (002) orientation. At an optimum oxygen pressure of 1x10^-3 mbar and substrate temperature of 663 K, the films exhibited an optical transmittance of 83% with a band gap of 3.28 eV.     

Optical investigations on the existence of phase transition in ZnO:Li thin films prepared by DC sputtering method

We investigated the effect of temperature on the absorption spectra of Zn_0.8Li_0.2O thin films (ZnO:Li), deposited at 573 K, in the wavelength range 190‐800 nm. The films were deposited on sapphire, MgO or quartz substrates by DC sputtering method. The results show a shift of the optical energy gap (E_g), with direct allowed transition type near the fundamental edge, to lower wavelengths as the temperature increases. The temperature rate of E_g changes considerably showing an anomaly around 320 K depending on type of substrate. The founded results indicated that replacement of Zn ions with Li ions induces a ferroelectric phase in the ZnO wurtzite‐type semiconductor. The exponential dependence of the absorption coefficient on the incident photon energy suggests the validity of the Urbach rule. (© 2007 WILEY ‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

衬底温度对直流磁控溅射法制备掺锆氧化锌透明导电薄膜性能的影响

利用直流磁控溅射法在石英衬底上制备出了高透明导电的掺锆氧化锌(ZnO:Zr)薄膜.研究了衬底温度对ZnO:Zr薄膜结构、形貌及光电性能的影响.XRD表明实验中制备的ZnO:Zr为六方纤锌矿结构的多晶薄膜,具有垂直于衬底方向的c轴择优取向.实验所制备ZnO:Zr薄膜的晶化程度和导电性能对衬底温度有很强的依赖性.当衬底温度为300 ℃时, ZnO:Zr薄膜具有最小电阻率7.58×10-4 Ω·cm,其可见光平均透过率超过了91;.     

Optical properties of thermally evaporated CdS thin films

CdS thin films of varying thicknesses were deposited on cleaned glass substrates at room temperature by thermal evaporation technique in a vacuum of about 2 x 10^‐5 torr. UV‐VIS spectra of the films were studied using the optical transmittance measurements which were taken in the spectral region from 300 nm to 1100 nm. The absorbance and reflectance spectra of the films in the UV‐VIS region were also studied. Optical constants such as optical band gap, extinction coefficient, refractive index, optical conductivity and complex dielectric constant were evaluated from these spectra. All the films were found to exhibit high transmittance (∼ 60 ‐ 93 %), low absorbance and low reflectance in the visible/near infrared region from ∼ 500 nm to 1100 nm. The optical band gap energy was found to be in the range 2.28 – 2.53 eV. All the films annealed at 300°C for 4 hours in vacuum (∼ 10^‐2 torr) showed a decrease in the optical transmittance with its absorption edge shifted towards the longer wavelength, leading to the result that the optical band gap decreases on annealing the films. Also, on annealing crystallinity of the films improves, resulting in decrease in the optical transmittance. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

直流磁控反应溅射法制备工艺参数对TiO2薄膜光催化性能的影响

采用直流磁控反应溅射法在未加热衬底上沉积TiO2薄膜,以紫外灯为光源进行了薄膜光催化降解亚甲基蓝溶液的实验,研究了沉积工艺参数和后处理退火温度对薄膜光催化性能的影响.结果表明:经过500℃退火、厚度较大的薄膜样品光催化效率较高;膜厚基本相同的样品,沉积时电源功率较小、Ar/O2流量比例较小的薄膜光催化效率较高.