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?。     

自适应遗传退火算法在薄膜椭偏测量中的应用

将自适应遗传模拟退火混合算法应用于薄膜椭偏测量的反演问题中.由于模拟退火算法的基本思想是跳出局部最优解而得到全局最优解,因此将模拟退火思想引入到遗传算法,遗传算法和模拟退火算法相结合,组建自适应遗传模拟退火算法,从而综合了全局优化和局部搜索的特点,并通过模拟计算,验证了此方法在薄膜椭偏测量问题中的可行性及有效性,为解决...     

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.     

用直流磁控溅射法制备的ＩＴＯ薄膜的光电性能研究

用直流磁控溅射法将ＩＴＯ薄膜制备在玻璃基片上以作为太阳电池的透明电极。通过改变溅射功率、基片温度和工作气压来研究它们对所沉积的ITO薄膜的透过率和电导率的影响。实验结果表明：当溅射功率从30W增加到90W时,薄膜的透过率和电阻率都将减小;当基片温度从25℃ 增加到 150℃时,透过率稍微有点增大但电阻率减小;当工作气压从0.4Pa 增大到2.0Pa时,透过率减小,但电阻率增大。因此,在溅射功率为30W、基片温度为150℃、工作气压为0.4Pa 时,ITO薄膜有比较好的光电性能,其电阻率小于10-4 Ω•cm ,在可见光波段的透过率大于80%,适合于作为太阳电池的透明电极。     

底电极对PYZT铁电薄膜电容器的影响

ＰＹＺＴ铁电薄膜电容器的制备采用ｓｏｌ－ｇｅｌ方法,将约５００ｎｍ厚的ＰＹＺＴ薄膜沉积在Ｐｔ／Ｔｉ、Ｐｔ／ＳｉＯ２及Ｐｔ／ＲｕＯ２底电极上,基片为Ｓｉ（１１１）。详细分析研究了ＰＹＺＴ薄膜在不同底电极,不同快速热处理温度下的晶相结构及ＰＹＺＴ铁电薄膜电容器的小信号特性。研究发现,沉积在Ｐｔ／ＲｕＯ２底电极上的ＰＹＺＴ薄膜经８００℃快速热处理具有较接近理想外延ＰＹＺＴ薄膜结构,而且εｒ随着快速热处理温度升高而减小,在８００℃快速热处理条件下其εｒ约为１５０。     

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。     

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.     

Photoelectric properties of ITO thin films deposited by DC magnetron sputtering

As anti-reflecting thin films and transparent electrodes of solar cells,indium tin oxide（ITO） thin films were prepared on glass substrates by DC magnetron sputtering process.The main sputtering conditions were sputtering power,substrate temperature and work pressure.The influence of the above sputtering conditions on the transmittance and conductivity of the deposited ITO films was investigated.The experimental results show that, the transmittance and the resistivity decrease as the sputtering power increases from 30 to 90 W.When the substrate temperature increases from 25 to 150℃,the transmittance increases slightly whereas the resistivity decreases.As the work pressure increases from 0.4 to 2.0 Pa,the transmittance decreases and the resistivity increases.When the sputtering power,substrate temperature and work pressure are 30 W,150℃,0.4 Pa respectively,the ITO thin films exhibit good electrical and optical properties,with resistivity below 10^-4Ω·cm and the transmittance in the visible wave band beyond 80%.Therefore,the ITO thin films are suitable as transparent electrodes of solar cells.     

Influence of pH of spray solution on optoelectronic properties of cadmium oxide thin films

Highly conducting transparent cadmium oxide thin films were prepared by the conventional spray pyrolysis technique. The pH of the spray solution is varied by adding ammonia/hydrochloric acid. The effect of pH on the morphology, crystallinity and optoelectronic properties of these films is studied. The structural analysis showed all the films in the cubic phase. For the films with pH < 7(acidic condition), the preferred orientation is along the(111) direction and for those with pH >7(alkaline condition), the preferred orientation is along the(200) direction.A lowest resistivity of 9.9104 cm(with carrier concentration D5.11020cm3, mobility D12.4 cm2/(V s))is observed for pH12. The resistivity is tuned almost by three orders of magnitude by controlling the bath pH with optical transmittance more than 70%. Thus, the electrical conductivity of CdO films could be easily tuned by simply varying the pH of the spray solution without compromising the optical transparency.     

半导体氮化物AlInN的光学性质

测量了AlInN薄膜(包括InN和AIN)的透射和反射光谱,结合四层透射和反射模型得到AlInN的一系列变温光学性质,包括吸收系数、能带带隙、乌尔巴赫带尾参数、折射率等等.采用一套经验公式,描述InN薄膜在本征吸收区和乌尔巴赫吸收区的吸收系数.发现带隙以下,AIN薄膜的折射率遵守Sellmeier经验公式.用基于态密度...     

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%。     

Investigation of post-thermal annealing on material properties of Cu-In-Zn-Se thin films

The Cu-In-Zn-Se thin film was synthesized by changing the contribution of In in chalcopyrite CuInSe2 with Zn.The XRD spectra of the films showed the characteristic diffraction peaks in a good agreement with the quaternary Cu-In-Zn-Se compound.They were in the polycrystalline nature without any post-thermal process,and the main orientation was found to be in the (112) direction with tetragonal crystalline structure.With increasing annealing temperature,the peak intensities in preferred orientation became more pronounced and grain sizes were in increasing behavior from 6.0 to 25.0 nm.The samples had almost the same atomic composition of Cu0.5In0.5ZnSe2.However,EDS results of the deposited films indicated that there was Se re-evaporation and/or segregation with the annealing in the structure of the film.According to the optical analysis,the transmittance values of the films increased with the annealing temperature.The absorption coefficient of the films was calculated as around 105 cm-1 in the visible region.Moreover,optical band gap values were found to be changing in between 2.12 and 2.28 eV depending on annealing temperature.The temperature-dependent dark-and photo-conductivity measurements were carried out to investigate the electrical characteristics of the films.