Influence of Sputtering Gas on Morphological and Optical Properties of Magnesium Films

The influence of sputtering gas(He & Ar) on the structural properties of Mg thin films has been investigated.The optical property(reflectance) that results from the growth of films at varying substrate temperatures(Tsub) was also studied.The deposited films were characterized by using X-ray diffraction(XRD),field emission scaning electron microscopy(FE-SEM),atomic force microscopy(AFM) and UV-Vis-NIR spectrophotometer.The smaller crystallite size and lower deposition rate were observed in the presence of Helium atmosphere compared to Argon.Morphology of the films shows 2D hexagonal geometry of grains in the deposition temperature range(Tsub≈50-150℃) in both the sputtering gases.The surface roughness of the polycrystalline films were found to increase with increase in the deposition temperature of both ambient gases.Optical reflectance of Mg films was measured in near infrared region and larger reflectance was observed from Mg films sputtered in He atmosphere compared to that in argon.     

真空蒸发沉积聚苯胺晶态薄膜的研究

利用傅里叶变换红外光谱、透射电子显微镜、高分辨扫描电子显微镜和扫描隧道显微镜等多种分析技术 ,对用真空蒸发沉积技术制备的不同聚苯胺 (PANI)薄膜试样进行了综合表征。研究发现 ,PANI薄膜是无定形态的绝缘膜 ;经HCl掺杂的PANI薄膜尽管其电导率有很大提高 ,但仍是非晶态的薄膜 ;而PANI TCNQ薄膜确是多晶薄膜 ,且薄膜的电导率较PANI薄膜提高几个数量级。研究发现PANI TCNQ薄膜中的PANI聚合链与TCNQ分子之间存在着电荷转移。与PANI薄膜和TCNQ薄膜相比 ,PANI TCNQ复合薄膜的结构更加完善 ,表面更加平整     

AFM Studies of Platinum Silicide Thin Films on Silicon Grown by Pulsed Laser Deposition

PtSi ultra-thin films were grown on Si-wafer using pulsed laser deposition(PLD).The surface structure of these films was studied by atomic force microscopy(AFM).In addition ,the compositional structure of the PtSi as deter-mined from X-ray photoelectron spectroscopy(XPS)is discussed.First report of a possible growth mechanism is presented, on studying the variation of morphological features(i,e,roughness and size of crystallites)with annealing temperatures and the film thicknesses..     

Structural and morphological characterization of Pr and Er-containing SiO2-P2O5 sol-gel thin films

Present work is focused on obtaining and characterization of sol-gel thin films belonging to SiO₂-P₂O₅-Er₂O₃ (I) and SiO₂-P₂O₅-Pr₂O₃ (II) systems. The films have been obtained by spin coating technique for three rotation speeds: 2000, 3500 and 5000 rpm. The deposition of the films was performed at different periods of time, i.e. 24 h, 96 h, 120 h, 144 h and 168 h after instant preparation of the precursor sols. FTIR (Fourier transform infrared spectroscopy) and Raman characterization aimed at investigating the structural changes that occurred in silicophosphate network in dependence on the spin rate of the substrate as well as on the time period elapsed since the sol preparation till the deposition day. FTIR spectra recorded in the 400-4000 cm⁻¹ range revealed Si-O-Si, P-O-P and Si-O-P vibration modes and optical phonons specific for OH units. Raman spectra collected in the 100-4000 cm⁻¹ range put in evidence stretching, bending and mixed vibration modes specific for silicophosphate network as well as rare-earth ion peaks specific to certain electronic transitions. Morphological investigation made by AFM (atomic force microscopy) on Er and Pr-doped silicophosphate sol-gel films evidenced specific features depending on the parameters mentioned above and SEM (scanning electron microscopy) analysis revealed micron sphere structural units, exfoliation of the films and micro cracks.     

Structural and magnetic properties of nickel catalyzed-tungsten oxide nanosheets synthesized using e-beam rapid thermal annealing

Nanosheets of nickel catalyzed tungsten oxide have been grown on Si (100) substrate by electron beam rapid thermal annealing (ERTA) process. The thin films of W and Ni were deposited in a conventional electron beam evaporation system under high vacuum conditions and then subjected to ERTA. Scanning electron microscopy and atomic force microscopy were used to study the systematic growth of the nanosheets. Nanosheets with a uniform thickness of 200 nm were obtained for the beam current of 9 mA with a voltage of 5 kV ERTA for 60 s. X-ray diffractograms indicate that the formation of multiple phases of nickel, nickel oxide and tungsten oxide with respect to the variation in the beam current. Vibrating sample magnetometer studies indicate that the magnetic properties of this system vary with the beam current.     

电子束反应蒸发氧化物薄膜的应力特性

研究了反应电子束蒸发氧化物光学薄膜在空气中的应力。为了找到能减小多层膜结构内应力的淀积工艺参数,测试了氧化物膜层TiO2,Ta2O5,SiO2,Al2O3,HfO2的应力,发现有些膜层为压应力,一些高折射率膜为张应力。实验表明,热处理可以有效地降低氧化物膜层光学吸收,并改变应力。     

不同衬底上低温生长的ZnO晶体薄膜的结构及光学性质比较

采用电子束反应蒸发方法,在单晶Si(001)及玻璃衬底上低温外延生长了沿c轴高度取向的单晶ZnO薄膜,并对沉积的ZnO晶体薄膜的结构和光学性质进行了分析比较。通过对ZnO薄膜的X射线衍射(XRD)分析及光致荧光激发谱(PLE)测量,研究了衬底材料结构特性、生长温度及反应气氛中充O     

真空蒸发制备Cd(Se,S)薄膜及其光学性能研究

利用真空蒸发技术在CdS粉末中掺入不同比例的Se粉末作源,选择合适的工艺条件在玻璃衬底上获得了性能稳定的Cd(Se,S)薄膜,薄膜为纤锌矿结构,具有沿[002]晶向的择优取向.Cd(Se,S)薄膜为n型材料,在可见光范围内具有良好的透过率.随Se成分的增加,薄膜由透明橘黄色变为透明棕红色,吸收限向长波方向移动.     

氩气氛下制备的C_(60)薄膜的形貌、结构和光学性质

用原子力显微镜 (AFM)、X射线衍射 (XRD)、红外光谱 (IR)及紫外 可见光谱 (UV/VIS)研究了在氩 (Ar)气氛下制备的C60 薄膜的表面形貌、结构及光吸收特性。发现其UV/VIS的强度和吸收峰位置明显不同于在真空中制备的C60 薄膜。与真空中制备的C60 薄膜比较 ,所研究薄膜的红外谱没有变化 ,但X射线衍射表明其结构从面心立方 (fcc)相变成fcc相与六角密堆(hcp)相的混合相。AFM表明 ,在Ar气氛中制备的C60 薄膜有较大的表面粒子 ,并且表面生长岛更尖锐。这将有利于C60 薄膜的场电子发射。     

酞菁铜薄膜的真空热蒸发制备及其性能

用真空热蒸发法在玻璃基板上制得酞菁铜(CuPc)薄膜。用原子力显微镜、紫外可见光分光光度计及红外光谱仪等分析了酞菁铜薄膜的结构特征,并对薄膜的沉积机理进行了探讨。通过与L-B(Langmuir-Blodgett)法的比较,发现用真空热蒸发法制备的酞菁铜薄膜结构、性能更佳。     

Microstructure and surface roughness study of highly crystallized μc-Si:H Films

We have deposited hydrogenated microcrystalline silicon films by standard rf glow discharge plasma CVD technique using a mixture of SiF₄, Ar and H₂ at low substrate temperatures. Although fully crystalline from the beginning of the growth, our films show a significant variation in the ratio of large (LG) and small grain (SG) with further growth, for any H₂ dilution case, though the trend changes for each case. The mean sizes of the LG and SG do not vary much with growth, but a marked variation occurs in the size of the conglomerate grains, as shown by atomic force microscopy (AFM) studies. Notably, a change in the H₂ dilution is found to affect not only the film microstructure, but also the crystalline orientation. We have shown the lateral and longitudinal growth of conglomerate grains to be highly dependent on the crystalline orientation. In studying the effect of film growth on film roughness, we have observed a linear correlation between the rms roughness as measured by AFM and the top surface layer as measured by spectroscopic ellipsometry. We have also succeeded in elucidating the growth mechanisms involved, apropos of surface roughness findings.     

S掺杂ZnO薄膜光电特性的研究

采用射频磁控溅射法,在玻璃基片上生长了ZnO:S薄膜。XRD测试表明所制薄膜为六角纤锌矿结构,具有明显的(002)衍射峰。室温下的透射光谱测量结果表明,随着S掺入量的增加,ZnO:S合金薄膜的吸收边向长波长方向移动,但在可见光部分有较高的透过率。在此基础上计算了各样品的禁带宽度,结果表明,在S掺入量小于8%的范围内,随着S掺入量的增加,禁带宽度减小。样品紫外光电导特性明显,在波长365nm、功率4000μW/cm2紫外光源照射下,紫外光与可见光所对应光电流响应之比可达3。     

Ag and O ion irradiation induced improvement in dielectric properties of the Ba(Co1/3Nb2/3)O3 thin films

We present the preliminary results of temperature and frequency dependent dielectric measurements on Ba(Co_1/3Nb_2/3)O₃ (BCN) thin films. These films were prepared on indium tin oxide (ITO) coated glass substrates by the pulse laser deposition (PLD) technique. It exhibits single-phase hexagonal symmetry. These films were irradiated with Ag¹⁵⁺ (200 MeV) and O⁷⁺ (100 MeV) beams at the fluence 1 × 10¹¹, 1 × 10¹², and 1 × 10¹³ ions/cm². On irradiating these films, its dielectric constant (?′) and dielectric loss (tan δ) parameters improve compared to un-irradiated film. Compared to O⁷⁺ irradiation induced point/cluster defects Ag¹⁵⁺ induced columnar defects are more effective in reducing/pinning trapped charges within grains. The present paper highlights the role of swift heavy ion irradiation in engineering the dielectric properties of conductive samples to enable them to be useful for microwave device applications.     

Effect of the microwave oven on structural, morphological and electrical properties of SrBi4Ti4O15 thin films grown on Pt/Ti/SiO2/Si substrates by a soft chemical method

Thin films of SrBi₄Ti₄O₁₅ (SBTi), a prototype of the Bi-layered-ferroelectric oxide family, were obtained by a soft chemical method and crystallized in a domestic microwave oven. For comparison, films were also crystallized in a conventional method at 700 °C for 2 h. Structural and morphological characterization of the SBTi thin films were investigated by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. Using platinum coated silicon substrates, the ferroelectric properties of the films were determined. Remanent polarization P_r and a coercive field E_c values of 5.1 μC/cm² and 135 kV/cm for the film thermally treated in the microwave oven and 5.4 μC/cm² and 85 kV/cm for the film thermally treated in conventional furnace were found. The films thermally treated in the conventional furnace exhibited excellent fatigue-free characteristics up to 10¹⁰ switching cycles indicating that SBTi thin films are a promising material for use in non-volatile memories.     

Influence of deposition temperature on structure and morphology of nanostructured SnO2 films synthesized by pulsed laser deposition

Nanostructured tin oxide thin films were deposited on the Si (100) substrate using the pulsed laser deposition technique at different substrate temperatures (300, 450 and 600 °C) in an oxygen atmosphere. The structure and morphology of the as-deposited films indicate that the film crystallinity and surface topography are influenced by the deposition temperature by changing from an almost amorphous to crystalline microstructure and smoother topography at a higher substrate temperature. The photoluminescence measurement of the SnO₂ films shows three stable emission peaks centered at respective wavelengths of 591, 554 and 560 nm with increasing deposition temperature, contributed by the oxygen vacancies.     

Morphological,Optical and DC Conduction Properties of a-GaSe Semiconductor Nanoparticle Thin Films

Amorphous gallium selenide （a-GaSe） semiconductor nanoparticle thin films were deposited onto well cleaned glass substrates by inert gas condensation （IGC） technique under a vacuum of 400 x 10-6 Pa （3 x 10-6 Torr）. The films were characterized by different structural and optical techniques, including X-ray diffraction, field emission scanning electron microscopy （FESEM）, field emission transmission electron microscopy （FETEM）, UV-visible absorption spectroscopy and I-V measurements. The particle size and size distribution were determined by TEM images which show the presence of spherical particles in the range of 5-50 nm in size. SEM images indicate that the a-GaSe film grown on glass substrate is almost smooth and dense. The optical properties of a-GaSe nanoparticle thin films were determined by optical absorption spectra. The optical bandgap of the film was estimated to be 2.19 eV and the transitions are allowed direct type. The electrical conductivity of the deposited films has been studied as a function of temperature. In the higher temperature range the dominance of thermally activated band conduction was observed; whereas in the low temperature ranqe the hoppinQ conduction in the band tails of localized states was found to be dominated.     

溶胶-凝胶法制备稀土掺杂多孔TiO2薄膜的表面形貌及性能研究

以溶胶－凝胶法,采用旋转涂膜工艺在玻璃表面制备了Ce,La掺杂的多孔TiO2薄膜,研究了玻璃表面TiO2薄膜在稀土掺杂及多孔化处理后的特征,发现稀土元素的掺杂使薄膜的多孔结构更加均匀一致,在近紫外的吸收率明显提高,同时对油酸有更高的光催化降解效率。