Annealing behavior of electroplated permalloy thin films

The isochronal annealing behavior of electroplated 1.2 μm Ni-Fe thin films containing nominally 80 wt% Ni, in the temperature range from 373° to 773°K, and with a magnetic field parallel to the easy axis of the films, was investigated through measurements of the films’ structural, magnetic and electrical properties. The effects of annealing could be described in terms of two annealing stages. In stage I, occurring up to about 575°K, recovery took place along with some pairordering, resulting in small decreases in the coercivity, the easy axis dispersion and the electrical resistivity; the apparent anisotropy field increased in this stage. The stage II of annealing, occurring above 575°K, was characterized by more defect annealing, a change in the texture and possibly some long-range ordering. This stage resulted in increases in the coercivity and the dispersion, along with decreases in the apparent anisotropy field, the apparent strain sensitivity and the relative permeability. The results of both annealing stages are discussed in terms of the structural changes.     

Preparation and electrical properties of inas thin films

Thin films of InAs have been deposited on mica substrates through a vacuum evaporation technique by means of controlling the substrate and source temperatures. The films with large crystal grain were found to have the best electrical properties. The maximum electron mobility of 12, 400 cm²/V·sec at room temperature was obtained in an undoped film of 3 Μm thickness at a donor concentration of 3.5 × 10¹⁶ cm⁻³. The temperature dependence of both electron mobility and resistivity of these films was slightly lower than those reported for bulk crystal type InAs.     

Computer simulation of transport in thin films

The effect of microstructure on the electrical transport behavior of polycrystalline ma-terials has been investigated by means of both experiment and computer simulation. The experiment was carried out by measuring the resistances of model thin film mi-crostructures. It was found that the topology of the microstructure significantly influ-ences the transport characteristics. The results were compared to the prediction of the current analytical theory (Brick-Layer model), and observed to be in significant dis-agreement. To overcome the limitation of this analytical theory, a computational meth-odology was developed to simulate the steady-state electrical transport. Comparison of the simulation results with the experiments shows good agreement. In investigating the transport behavior of polycrystalline films having grain boundary of high resistance, grain size and morphology are found to have two effects on the conduction process. First, they can lead to an increase in the length of the equipotential contours due to the fact that they follow the preexisting grain boundary. Second, the large grains can serve to shunt the flux pass adjacient smaller grains. Both of these effects lead to a decrease in the total resistance as the microstructure departs from a regular Brick-Layer type struc-ture.     

La0.6Sr0.4CoO3薄膜的制备及NTC特性研究

为研制具有较低室温电阻值的NTC薄膜热敏电阻,以La0.6Sr0.4CoO3陶瓷为靶材,采用RF磁控溅射法,在Al2O3基片上沉积了La0.6Sr0.4CoO3(LSCO)薄膜。研究了溅射过程中氩氧体积流量比对LSCO薄膜结晶性能和方阻的影响以及LSCO薄膜的阻温特性。结果表明:随着氩氧体积流量比的增加,LSCO薄膜的主晶相衍射峰强度及方阻均先增大后减小。LSCO薄膜具有显著的NTC特性,室温时的电阻温度系数α25为2.24×10–5;其lnR-T–1曲线具备良好的线形度,线性偏差仅为2.09%;另外,其室温时的电阻R25仅为18.75k?。     

Numerical simulation of thermal wave propagation during laser processing of thin films

A numerical model is developed to represent the thermal wave propagation during ultrashort pulsed laser processing of thin films. The model developed is based on the solution of non-Fourier heat conduction problem with temperature and thermal flux delays using discontinuous finite-element method. The mathematical formulation is described and computational procedures are given. The computer model is validated using the analytical solution for one-dimensional (1-D) thermal wave equations. Numerical simulations are performed to study the thermal wave propagation in a GaAs thin film exposed to ultrashort laser pulses. A wavelike behavior of the thermal signal propagation is observed, and the diffusive effect of the time relaxation in the temperature gradient is calculated and discussed. The thermal behavior of thin films under laser radiation is also studied as a function of various process parameters including pulse duration, laser pulse shapes and characteristic times of heat fluxes.     

制备工艺对ITO薄膜的电阻率及沉积速率的影响

采用射频磁控溅射法制备了氧化铟锡[ITO,In2O3:SnO2=90:10(质量比)]薄膜,详细探讨了溅射气氛氧氩体积比、溅射功率及溅射气压对ITO薄膜电阻率和沉积速率的影响。结果表明:溅射工艺参数对ITO薄膜电阻率和沉积速率的影响十分明显。随着氧氩体积比的增大,样品的电阻率显著增大,沉积速率下降;随着溅射功率的增加,ITO薄膜的电阻率先减小后略微增大,沉积速率上升;随着溅射气压升高,ITO薄膜的电阻率先减小后增大,当溅射气压增大到较大值时,ITO薄膜的电阻率又开始减小,而沉积速率则先上升后下降。     

磁控溅射ZnO薄膜的退火热力学行为研究

本文利用原子力显微镜、透射电子显微镜、X射线衍射等分析手段研究了反应射频磁控溅射截然不同的阶段,其临界转变温度在790 ℃附近.进一步分析表明,决定低温退火的晶粒长大机制为Zn填隙原子扩散机制,而决定高温退火时的晶粒长大机制为O空位扩散机制.界面分析结果显示:在临界转变温度以下,ZnO薄膜与基体Si之间基本不发生界面反应;在高温退火过程中,ZnO薄膜与基体Si之间的界面反应主要以氧化后的Si表面层向ZnO扩散的方式进行,并导致了薄膜应力的迅速增加,而界面反应开始之前的薄膜应力的变化,则是由于晶粒合并所引起的.     

Thermomechanics of thin films and interfaces

Several mechanics and thermomechanics problems associated with the deposition of thin films on substrates are reviewed. They include: (1) Stress concentrations in interfacial cracks, and the corresponding calculation of the energy release rate for crack growth along the film-substrate interface. (2) The effect of microstructure and of stress relaxation by diffusional creep during the growth of a thin film on the residual stresses present in the film; and (3) the thermal conductivity in film-substrate assemblies, and the issue of extracting film thermal properties from composite measurements. The relation between bulk and thin film values of the thermal conductivity is discussed. The issue of interfacial thermal resistance, which may lead to interfacial temperature drops of the order of 0.6° K is also addressed, and discussed in view of the inhomogeneous interface in films deposited by electron beam evaporation or ion beam sputtering.     

Thermal stability of sputter-deposited ZnO thin films

This paper describes our investigation on the thermal stability of sputterdeposited, piezoelectric, ZnO thin films, using x-ray photoelectron spectroscopy (XPS), capacitance-voltage (C-V) measurements of metal-insulator-semiconductor structures, and electron microprobe. We focus on out-diffusion of Zn from ZnO thin films at a high temperature (450°C) and the composition change of zinc and oxygen after high temperature annealing (up to 700°C), since these factors are related to reliability and integrated circuits-process-compatibility of the ZnO films which are being used increasingly more in microtransducers and acoustic devices. Our experiments with electron microprobe show that ZnO thin films sputter-deposited from a ZnO target in a reactive environment (i.e., with O₂) are thermally stable (up to 700°C). Additionally, the out-diffusion of zinc atoms from the ZnO films at a high temperature (450°C) is verified to be negligible using the XPS and C-V measurement techniques. The usage of a compound ZnO target, reactive environment with O₂ and optimized deposition parameters (including gas ratio and pressure, substrate temperature, target-substrate distance and rf power, etc.) is critical to deposit thermally stable, high quality ZnO films.     

退火温度对电子束蒸发的ZnS薄膜性能的影响

为了获得光电性能好的ZnS窗口层薄膜,采用电子束蒸发法在玻璃基片上沉积ZnS薄膜,研究退火温度(200~500℃)对ZnS薄膜的结构和光电性能的影响。结果表明:所制备的薄膜均为闪锌矿结构的β-ZnS多晶薄膜,导电类型为n型。随着退火温度的增高,薄膜结晶度和光电性能都变好。但是,当退火温度过高(500℃)时,薄膜的半导体特性反而变差。退火温度为400℃时,ZnS薄膜的性能最佳,此时薄膜的透过率较高;电阻率较低,为246.2?.cm。     

厚度对TaN薄膜电性能的影响研究

采用直流反应磁控溅射法制备了TaN薄膜,研究了薄膜厚度对TaN薄膜微观结构及电性能的影响。结果表明,薄膜厚度对TaN薄膜的表面形貌和相结构都没有影响,但会显著影响TaN薄膜的电学性能。在87~424 nm的范围内,随着薄膜厚度的增大,所制TaN薄膜的电阻率从555×10–6.cm减小到285×10–6.cm,方阻从84/□减小到9/□,电阻温度系数(TCR)从–120×10–6/℃增加到+50×10–6/℃。可以通过调节薄膜的厚度调节TaN薄膜的电阻率和TCR。     

Si基外延Ge薄膜及退火对其特性的影响研究

采用超高真空化学气相沉积(UHV-CVD)系统,用低温Ge缓冲层技术在Si衬底上外延了张应变Ge薄膜.扫描电镜(TEM)图表明Si基外延Ge薄膜拥有低的位错密度,原子力显微镜(AFM)测试Ge层表面粗糙度仅为1.2 nm.对Si基外延Ge薄膜进行了不同温度下的退火,并用双晶X射线衍射(DCXRD)曲线和Raman谱进行...     

磁控溅射AZO透明导电薄膜及其光电性能的研究

采用磁控溅射法在石英玻璃衬底上制备AZO薄膜。利用X射线衍射仪、原子力显微镜、四探针测试仪和透射光谱仪等手段研究了衬底温度对AZO薄膜结构、形貌、光电性能的影响。结果表明,所有的AZO薄膜均为纤锌矿结构且具有较好的c轴取向。薄膜表面平整,晶粒约为55.56 nm。随着衬底温度升高,薄膜电阻率先降低而后升高,当衬底温度为350℃时,电阻率最小,约为1.41×10–3?·cm,而且该薄膜具有较好的透光率,约为84%。     

中温退火对坡莫合金薄膜AMR的影响

制备了纳米级(Ni82Fe18)72．9Nb27．1(3．5nm)／Ni82Fe18(tnm)／Ta(3nm)坡莫合金系列膜，并进行了中温退火(200℃)，测量了退火前后样品的零场电阻率(ρ)，各向异性磁电阻(AMR)和微结构；从实验角度研究了中温退火对ρ和AMR随NiFe厚度(t)变化的影响，并探讨了该影响的微观机制。     

水热—溶胶凝胶法制备PZT薄膜

采用水热—溶胶凝肢法制备了锆钛酸铅( PZT)压电陶瓷薄膜.首先利用水热法处理Si基板,使之生成SiO2/Si层,然后采用旋涂法在处理好的Si基板上涂覆摩尔比r(Zr:Ti)为52:48的PZT前驱体溶胶.研究了基板处理方式、退火温度以及涂胶层数对PZT薄膜结晶性能、表面形貌及厚度的影响.结果表明:水热处理Si基板对P...     

Chlorine-doped CdS thin films from CdCl<Subscript>2</Subscript>-mixed CdS powder

The CdS:Cl thin films have been prepared using thermally evaporated, CdCl₂-mixed CdS powder at 200°C substrate temperature. The percentage of CdCl₂ in the mixture varied from 0% to 0.20%. The electrical properties and the grain size of the deposited films were investigated. The results show that light doping, resistivity, carrier concentration, and mobility follow Seto’s model for polycrystalline material. However, with heavy doping, these properties undergo a saturation trend. The saturation behavior can be understood in terms of the rapid formation of the A-center complexes in the films. The deposited films were annealed at 250°C and 300°C. The resistivity of pure and lightly doped CdS films increased with annealing temperature, whereas carrier concentration and mobility in these films decreased. However, for the higher doping concentrations, the resistivity decreased, whereas carrier concentration and mobility showed improvement. These changes in electrical properties of the deposited films with annealing and doping concentration are attributed to a reduction in the lattice defect sites in CdS upon annealing. The experimental results are interpreted in terms of a modified version of Seto’s model for polycrystalline materials.     

LSMCD技术制备PLT铁电薄膜的退火工艺研究

液态源雾化化学沉积(LSMCD)技术自1992年问世以来就引起了各国科学家的广泛关注。目前，已成功制备出了多种铁电薄膜。该文系统的分析了采用LSMCD技术制备PLT铁电薄膜在退火温度和退火方式的选择对其相结构的影响，在保证PbO不挥发的情况下，退火温度越高，薄膜的结晶越好；采用混合热处理(RCA)制备的薄膜晶粒尺寸较大，形成了连续致密的薄膜，而快速热处理(RTA)虽可以消除焦绿石相，但薄膜晶粒较小。     

射频磁控溅射法制备Cu2ZnSnS4薄膜

利用射频磁控溅射法在玻璃基片上制备了Cu2ZnSnS4( CZTS)薄膜,薄膜在室温下生长,再在Ar气氛中快速退火.通过X射线衍射、X射线电子能谱、原子力显微镜和吸收谱研究了退火温度对薄膜结构、组分、形貌和禁带宽度的影响.结果表明,所制备样品为Cu2ZnSnS4多晶薄膜,具有较强的沿(112)晶面择优取向生长的特点,薄膜组分均为富S贫Cu,样品表面形貌比较均匀.退火温度为350,400,450和500℃的薄膜样品的禁带宽度分别是1.49,1.53,1.51和1.46 eV.     

Preparation of ferroelectric PLZT thin films

Transparent ferroelectric PLZT thin films were prepared on fused-quartz substrates by rf sputtering using a powder target of pulverized ceramic PLZT. The substrate temperature was kept above 550° C to obtain the film. Excess PbO in the target may act as a sort of flux for crystal growth. The dielectric constant of the film was 500 at room temperature and the film showed a ferroelectric hysteresis curve. By an appropriate annealing, the transparency of the film became improved. The electrooptic effects of the film was measured for the first time. The light intensity reflected from the film was changed strongly by application of the electric field. With light incident at 70° , an intensity change of 33% was obtained at the electric field of 12.5kV/cm.     

Effects of annealing in O2 and N2 on the electrical properties of tantalum oxide thin films prepared by electron cyclotron resonance plasma enhanced chemical vapor deposition

The tantalum oxide thin films with a thickness of 14 nm were deposited at 95°C by electron cyclotron resonance plasma enhanced chemical vapor deposition (ECRPECVD), and annealed at various temperatures (700∼850°C) in O₂ and N₂ ambients. The microstructure and composition of the tantalum oxide thin films and the growth of interfacial silicon oxide layer were investigated and were related to the electrical characteristics of the film. Annealing in an O₂ ambient led to a high dielectric constant (ε_r(Ta₂O₅) = 24) as well as a small leakage current (E_bd = 2.3 MV/cm), which were due to the improved stoichiometry and the decreased impurity carbon content. Annealing in an N₂ ambient resulted in poor and nonuniform leakage current characteristics. The as-deposited tantalum oxide films were crystallized into δ-Ta₂O₅ after annealing at above 750°C regardless of the ambient. The leakage current of the film abruptly increased after annealing at 850°C probably because of the stress caused by thermal expansion or contraction.