Mn、Co掺杂ZnO薄膜结构及发光特性研究

利用脉冲激光沉积(PLD)方法在Si(100)衬底上制备了ZnO、Zn0.8Mn0.2O、Zn0.8Co0.2O薄膜.薄膜的晶体结构和表面形貌采用X射线衍射仪和原子力显微镜测试.表明薄膜具有明显的c轴择优生长取向,薄膜表面较为平整,颗粒尺寸在纳米量级,薄膜中晶粒的生长模式为"柱状"模式.此外,Mn、Co掺入后,薄膜的X射线衍射峰有小角度偏移,这与 Mn2 、Co2 离子半径有关.PL谱显示Mn、Co掺杂ZnO薄膜的蓝、绿发光峰的位置相对纯的ZnO薄膜没有改变,还出现了紫外发光峰,其中Mn掺杂的蓝、绿光峰的强度减弱,Co掺杂的蓝光峰强度减弱,绿光峰强度增强.这是因为Mn、Co掺入改变了ZnO本征缺陷的浓度,发光峰的强度也随之而改变.     

Characterisation of oxidised erbium films deposited on Si(1 0 0) substrates

Thin Er-oxide films were prepared by oxidation of pure Er films grown on glass and Si (p) substrates. The oxide films were characterised by X-ray fluorescence (XRF), X-ray diffraction (XRD), and optical absorption spectroscopy. The XRD analysis of the as-prepared oxide film and the vacuum-annealed film demonstrates the formation of Er₂O₃ phase with about 4.6% of ErO phase, which totally transforms into Er₂O₃ phase under annealing at 600 °C in dry oxygen. Therefore, the phase-structural changes in the prepared Er-oxide films because of the annealing and the long-time storage in vacuum were studied. The constructed Al/Er-oxide/Si MOS devices were characterised by measuring gate-voltage dependence of their capacitance and ac conductance, from which the surface states density (D_it) of insulator/semiconductor interfacial charges and the density of fixed charges in the oxide, were determined, which were within the device-grade range. The ac-electrical conduction and dielectric properties of the of the Er oxide–silicon structure were studied at room temperature. The data of ac conductivity measurements were found to follow the correlated barrier-hopping (CBH) model and the model's parameters were calculated, while the Kramers–Kronig (KK) relations explain the high-frequency dependence of the capacitance.     

Vanadium dioxide thin film with low phase transition temperature deposited on borosilicate glass substrate

A nanostructured vanadium dioxide (VO₂) thin film showing a low metal-insulator transition temperature of 30 °C has been fabricated through reactive ion beam sputtering followed by thermal annealing. The thin film was grown on borosilicate glass substrate at the temperature of 280 °C with a Si₃N₄ buffer layer. Both scanning electron microscopy and atomic force microscopy images have been taken to investigate the configuration of VO₂ thin film. The average height of the crystallite is 20 nm and the grain size ranges from 40 nm to 100 nm. The transmittance measured from low to high temperatures also reveals that the film possesses excellent switching property in infrared light at critical transition temperature, with switching efficiency of 52% at 2600 nm. This experiment paves the way of VO₂ thin film's application in smart windows.     

镍酸镧导电薄膜的热处理制度与电性能研究

研究了镍酸镧(分子式LaNiO3,简称LNO)导电薄膜的制备,及其与性能之间的关系。实验结果表明热处理制度和热处理过程中通氧是LNO薄膜获得良好电性能的关键。实验发现LNO薄膜在退火温度5500C时就已经晶化,并且随着退火温度的升高,薄膜电性能也随之提高,但是当温度高于860℃后,LNO薄膜发生了结构相变并伴有NiO的析出,因此导致了薄膜电阻率的升高。较短的预处理时间和较长的退火处理时间有助于薄膜晶粒的长大,从而提高薄膜的电性能。同时也讨论了LNO薄膜电阻率和工作温度的关系。     

Correlation study between structural, magnetic and transport properties of annealed Co thin films

This paper presents structural, magnetization and transport properties measurements carried out on as-deposited Co (400 Å) thin film as well as samples annealed in the temperature range 100-500 °C in steps of 100 °C for 1 h. The samples used in this work were deposited on float glass substrates using ion beam sputtering technique. The magnetization measurements carried out using MOKE technique, clearly indicates that as-deposited as well as annealed samples up to 500 °C show well saturation magnetization with applied magnetic field. The as-deposited sample shows coercivity value (H_c) of 26 Oe, and it is increased to 94 Oe for 500 °C-annealed sample. A minimum coercivity value of 15 Oe is obtained for 200 °C annealed sample. The XRD measurements of as deposited films show microcrystalline nature of Co film, which becomes crystalline with increase in annealing temperature. The corresponding resistivity measurements show gradual decrease in resistivity. AFM technique was employed to study the surface morphology of as deposited film as well as annealed thin films. Observed magnetization, and resistivity behaviour is mainly attributed to the (i) change in crystal structure (ii) increase in grain size and (iii) stress relaxation due to the annealing treatment.     

Quality improvement of organic thin films deposited on vibrating substrates

Most of the Organic Light-Emitting Diodes (OLEDs) have a multilayered structure composed of functional organic layers sandwiched between two electrodes. Thin films of small molecules are generally deposited by thermal evaporation onto glass or other rigid or flexible substrates. The interface state between two organic layers in OLED device depends on the surface morphology of the layers and affects deeply the OLED performance. The morphology of organic thin films depends mostly on substrate temperature and deposition rate. Generally, the control of the substrate temperature allows improving the quality of the deposited films. For organic compounds substrate temperature cannot be increased too much due to their poor thermal stability. However, studies in inorganic thin films indicate that it is possible to modify the morphology of a film by using substrate vibration without increasing the substrate temperature. In this work, the effect of the resonance vibration of glass and silicon substrates during thermal deposition in high vacuum environment of tris(8-quinolinolate)aluminum(III) (Alq₃) and N,N′-Bis(naphthalene-2-yl)-N,N′-bis(phenyl)-benzidine (β-NPB) organic thin films with different deposition rates was investigated. The vibration used was in the range of hundreds of Hz and the substrates were kept at room temperature during the process. The nucleation and subsequent growth of the organic films on the substrates have been studied by atomic force microscopy technique. For Alq₃ and β-NPB films grown with 0.1 nm/s as deposition rate and using a frequency of 100 Hz with oscillation amplitude of some micrometers, the results indicate a reduction of cluster density and a roughness decreasing. Moreover, OLEDs fabricated with organic films deposited under these conditions improved their power efficiency, driven at 4 mA/cm², passing from 0.11 lm/W to 0.24 lm/W with an increase in their luminance of about 352 cd/m² corresponding to an increase of about 250% in the luminance with respect to the same OLEDs fabricated in the same way and with the same conditions without substrate vibration.     

Initial growth of SnO2 thin film on the glass substrate deposited by the spray pyrolysis technique

Spray pyrolysis of di-n-butyltin(IV) diacetate (DBTDA) has led to the deposition of [200]-oriented SnO₂ film on a glass substrate. In order to clarify growth mechanism of the preferential orientation the sprayed SnO₂ thin film has been investigated by using the atomic force microscopy and the X-ray photoelectron spectroscopy. The results have suggested that the sprayed solution forms the SnO₂ small particles on the glass substrate and they spread overall relatively soon. At the very early stage each particle grows with almost the same rate and only its density increases with no change in a surface roughness.     

Abnormal photoluminescence of ZnO thin film on ITO glass

The photoluminescence (PL) properties of ZnO thin films on ITO glass substrate deposited by rf magnetron sputtering with different oxygen partial pressures were studied. It was found that the exciton related emission of ZnO thin films depends on oxygen partial pressure, and that the visible emission related to intrinsic defects has no obvious change with various oxygen partial pressures. Abnormal UV-PL characteristics were observed, and its intensity was obviously enhanced. The emission position has a strong red-shift with increasing excitation intensity, and the emission intensity increases notably with increasing excitation cycle.     

The effect of Fe-doped magnesium oxide thin film in alternative current plasma display panel

In order to improve the discharge characteristics of MgO thin film as a protective layer in an alternative current plasma display panel, Fe-doped MgO thin films was introduced. Both the surface characteristics of the deposited thin films and the electro-optical properties of 4 inch test panels were investigated. It has been demonstrated experimentally that ac PDP with Fe-doped MgO protective layer has lower discharge voltage than that of undoped MgO film, which corresponds to measured secondary electron emission coefficients. The crystallinity and surface roughness of thin films were determined by XRD patterns and AFM images.     

Recombination luminescence and trap levels in undoped and Al-doped ZnO thin films on quartz and GaSe (0 0 0 1) substrates

Photoluminescence spectra of ZnO and ZnO:Al (1.00, 2.00 and 5.00 at.%) films on GaSe (0 0 0 1) lamellas and amorphous quartz substrates, obtained by annealing, at 700 K, of undoped and Al-doped metal films, are investigated. For all samples, the nonequilibrium charge carriers recombine by radiative band-to-band transitions with energy of 3.27 eV, via recombination levels created by the monoionized oxygen atoms, forming the impurity band laying in the region 2.00 ? 2.70 eV. Al doping induces an additional recombination level at 1.13 eV above the top of the valence band of ZnO films on GaSe substrates. As a result of thermal diffusion of Zn and Al into the GaSe interface layer from ZnO:Al/GaSe heterojunction, electron trap levels located at 0.22 eV and 0.26 eV below the conduction band edge of GaSe, as well as a deep recombination level, responsible for the luminescent emission in the region 1.10 ? 1.40 eV, are created.     

A molecular dynamics simulation of TiN film growth on TiN(0 0 1)

The growth of thin TiN films on the TiN(0 0 1) surface during reactive sputtering was simulated by molecular dynamics with the modified embedded-atom method potential. TiN₃ is found to be the smallest epitaxial island and the film grows via the layer mode. Vacancy concentration in the deposited films decreases with increasing the substrate temperature and kinetic energy of incident atoms, resulting from the enhancement of the thermal diffusion and kinetic energy assisted athermal diffusion. To get the stoichiometric TiN film, the N:Ti flux ratio should be larger than unity and be increased with higher incident energy due to the weak adsorption of atomic N on TiN(0 0 1).     

多弧离子镀在不锈钢板上沉积TiN的均匀性研究

本文对多弧离子镀在不锈钢板上沉积TiN涂层的均匀性进行了研究,分析了影响涂层均匀性的主要因素.结果表明,弧基距、磁场强度、气体压力及基片温度对涂层的均匀性起着决定性的作用.     

Anharmonic effects on Be(0 0 0 1): A molecular dynamics study

Using molecular dynamics simulations and a modified analytic embedded atom method (MAEAM), the anharmonic effects of Be(0 0 0 1) surface have been studied in the temperature range from 0 K to 1400 K. The temperature dependence of the interlayer separation, mean square vibrational displacement, phonon frequencies and phonon line width, and layer structure factor are calculated. The obtained results for temperature dependence of interlayer separation and mean square displacement show that the anharmonic effects are small in the temperature range from 0 K to 1100 K. The calculated layer order parameters indicate that Be(0 0 0 1) surface loses its long-range translational order, but do not premelt up to 50 K below the bulk melting point. The surface disordering may result from strongly contracted c/a ratio of Be.     

磁控溅射法沉积纳米Cu薄膜的性能研究

采用卷绕型磁控溅射设备在涤纶(PET)针刺毡表面沉积了纳米结构Cu薄膜,利用X射线衍射仪(XRD)对薄膜的组分和结晶状态进行了分析,用原子力显微镜(AFM)分析了不同溅射工艺参数对纳米Cu薄膜微观结构和颗粒直径的影响,并较为系统地分析了溅射功率、工作气压和沉积时间对镀铜PET针刺毡导电性能的影响。结果表明,增大溅射功率,镀铜PET针刺毡导电性和Cu膜均匀性变好,但应控制在6kW以下;随工作气压的增大,薄膜方块电阻先减小后增大,薄膜厚度更加均匀;随着沉积时间的延长,Cu粒子的直径增大,Cu膜的导电性和均匀性明显变好。     

多孔硅表面氧化钒热敏电阻薄膜的阻温特性

用电化学腐蚀法制备了具有不同导热系数的多孔硅样品(孔隙率为80％±2、厚度为110μm时,导热系数可降低至0．20 W／m·K),并在其表面沉积了氧化钒热敏薄膜,研究了多孔硅样品的热绝缘性能对氧化钒热敏薄膜阻温特性的影响．结果表明:多孔硅良好的热绝缘性使在其表面制备的氧化钒热敏薄膜电阻的灵敏度远高于在硅基底上制备的热敏电阻的(多孔硅和硅片上的氧化钒薄膜电阻随功率变化斜率分别为120 kΩ／μW和2．1 kΩ／μW),且热敏电阻的灵敏度随着多孔硅孔隙率和厚度的增大而升高．     

Co掺杂量对ZnO薄膜结构及光学特性的影响

采用脉冲激光沉积法(PLD)在SiO2村底上成功制备了具有c轴择优生长特性的Zn1-xCoxO(x=0.05、0.1、0.2、0.3)系列薄膜.通过X射线衍射和能谱仪研究了Co掺杂量对薄膜晶体结构和成分的影响;同时利用光致发光谱(PL)和透过率研究了薄膜的光学特性.结果表明,当掺杂浓度为10%时,薄膜生长最好,c轴择优生长最为显著;Co元素的掺入改变了薄膜的紫外、绿光和蓝光发射,分析认为主要是Co元素的掺入量改变了薄膜的禁带宽度、氧错位缺陷浓度和锌填隙缺陷的浓度;Co元素掺杂浓度为5%时,薄膜的透过率超过90%.此外,探讨了不同波段光发射的可能机理.     

玻璃衬底和Si衬底制备的Zn0.96Nd0.04O薄膜的结构研究

通过射频磁控溅射技术在玻璃衬底和Si（111）村底上制备了Zn0.96Nd0.04O薄膜。XRD分析表明,Zn0.96Nd0.04O薄膜是具有C轴择优生长的纳米多晶薄膜,Nd以替位原子的形式存在于ZnO晶格,Nd掺杂没有改变ZnO晶格结构。从AFM图中看出,薄膜表面形貌较为粗糙,Si衬底薄膜的晶粒具有规律且晶粒尺寸大于玻璃衬底。     

沉积速率对EB-PVD Ni-Cr薄膜表面形貌的影响

采用动态蒙特卡罗(KMC)方法模拟电子束物理气相沉积(EB-PVD)制备Ni-Cr合金薄膜过程中沉积速率与薄膜微观结构之间的关系,并用分维理论研究薄膜表面形貌.研究结果表明:对于基板温度为500K,入射角度为35°的情况,沉积速率＜5μm/min时,薄膜表面分维均＜2.04,表面光滑,而当沉积速率＞5μm/min时薄膜分维随沉积速率增大而增大,表面变得越来越粗糙,直到沉积速率升高到1000μm/min时,分维达到最大值2.31,表面非常粗糙,具有细致的皱褶和缺陷.分维与沉积速率间的关系说明低沉积速率有利于分维小、表面光滑薄膜的制备,而高沉积速率使薄膜分维增大、表面结构更加复杂.该研究结果与沉积速率对EB-PVD薄膜表面粗糙度影响的研究结果一致,表明分维也是评价薄膜表面形貌的途径.     

Deposition and structural characterization of poly-Si thin films on Al-coated glass substrates using hot-wire chemical vapor deposition

The growth of polycrystalline Si films onto Al-coated Corning 7059 glass substrates using hot-wire chemical vapor deposition (HW-CVD) was investigated. The crystalline fraction, grain structure and average grain size of the films were compared as a function of the growth rate and the Si/Al thickness ratio. Micrometre-size Si grains were achieved with a Si/Al ratio of 2 and Si thickness of 2 μm at a growth rate of 1 μm h⁻¹. It was found that the films had a bimodal grain size distribution, which included nanocrystalline Si, and that the growth of micrometre-size crystallites does not continue as the thickness of Si film increases. At a growth rate of 5 μm h⁻¹, films are similar to those grown on glass with an average grain size less than 60 nm and crystalline fraction of 75%.     

具有一定取向的TiO2薄膜的研究与制备

用浸渍法将P25粉末涂敷于溶胶-凝胶法制备的TiO2预制膜上,进行一系列的热处理,制备TiO2薄膜样品.用X射线衍射法对样品进行晶体结构分析,发现用这种方法可以得到具有一定取向的TiO2薄膜.其结晶程度和取向度与浸渍时间和热处理时间相关,在浸渍时间为10h、热处理温度为500℃时,得到沿(101)面方向取向生长的TiO2薄膜.