Effect of Nanocrystallization on Magnetic Properties and GMI Effect of Fe-rich Microwires

We studied the giant magnetoimpedance (GMI) effect and magnetic properties of Finemet-type FeCuNbSiB microwires. We observed that the GMI effect and magnetic softness of glass-coated microwires produced by the Taylor–Ulitovski technique can be tailored by controlling the magnetoelastic anisotropy of as-prepared FeCuNbSiB microwires, and can also be considerably improved either by heat treatment and/or choosing the suitable fabrication conditions. We observed a considerable magnetic softening of the microwires after the appropriate annealing. This magnetic softening correlates with the devitrification of amorphous samples. Amorphous Fe-rich microwires exhibited a low GMI effect (GMI ratio below 5%). A considerable enhancement of the GMI effect (GMI ratio up to 100%) has been observed in heat-treated microwires with nanocrystalline structure.     

CoFe涂层对非晶薄带GMI效应的影响

上制备不同厚度的CoFe薄膜层,观察其巨磁阻抗(GMI)效应在120 kHz~3 MHz频率范围内随外加磁场的变化。实验结果显示,在Co基非晶薄带上涂覆CoFe薄膜,可提高薄带的GMI效应。研究发现,当趋肤效应显著时材料表面粗糙度对GMI效应有较大影响。通过在Co基非晶薄带表面镀膜的方式降低样品表面粗糙度,减小表面退磁场的影响,并闭合样品磁通回路,从而提高样品GMI效应。     

软磁非晶丝巨磁阻抗效应传感器研究进展与应用

基于软磁非晶丝巨磁阻抗效应(GMI)的传感器是近年来磁传感器领域的研究热点之一.非晶丝具有良好的软磁特性:如低电阻率、高磁导率、高饱和磁感应强度、低矫顽力、低损耗以及特殊的磁畴结构等,利用其GMI效应制成磁传感器,其突出优点是微型化、高灵敏度、快速响应、高温度稳定性和低功耗.本文讨论了软磁非晶丝巨磁阻抗效应的机理,叙述了非晶丝GMI传感器的研究进展,着重对敏感材料性能及制备、GMI器件结构形式、传感电路等作了介绍,并指出了GMI目前存在的问题及将来的发展趋势.最后对GMI的应用作了展望.     

非晶InP薄膜的光学性质与退火效应

本文研究由射频溅射法制备的非晶InP薄膜的光学性质及其退火效应.薄膜光学性质由椭圆偏振光谱法测量.退火是在300、350、400、420℃的温度下于密闭容器中进行.结果表明,经400℃退火后,薄膜光学性质发生明显改变,反映薄膜已由非晶态转变为多晶态.指出用光学性质的改变来描述晶化过程可能更加灵敏.     

Influence of Nanocrystallization on Magnetic Properties of the Co-Based Alloys Thin Films

Since Yoshizawa et al found iron-basednanocrystalline soft magnetic materials in 1988[1],nanocrystalline soft magnetic thin films have attractedmuch attention due to their wide applications.According to the random anisotropy model proposedby Herzer[2,3], as grain size is smaller than theexchange correlation length, coercivity andpermeability will be proportional and inverselyproportional to the grain size to sixth power,respectively. Therefore, in order to reach excellent softmagnetic properti…     

Optical Properties of Nanocrystalline GaN Films Prepared by Annealing Amorphous GaN in Ammonia

Nanocrystalline GaN films were prepared by thermal treatment of amorphous GaN films under flowing NH₃ at a temperature of 600°C to 950°C for 1 h to 2 h. X-ray diffraction and field-emission scanning electron microscopy confirmed the formation of high-crystal-quality hexagonal GaN films with preferential (002) orientation. The photoluminescence spectrum showed a sharp peak near the band gap emission located at 368 nm and a broad blue peak centered at 430 nm. Five first-order Raman modes near ∼143 cm⁻¹, 535 cm⁻¹, 555 cm⁻¹, 568 cm⁻¹, and 731 cm⁻¹ with two new additional Raman peaks at 257 cm⁻¹ and 423 cm⁻¹ were observed. The origin of these new Raman peaks is discussed briefly.     

Multilayer Microwires: Tailoring Magnetic Behavior by Sputtering and Electroplating

A novel technique for preparing multilayer microwires with controlled magnetic behavior has been developed. This technique involves combining sputtering and electroplating procedures to deposit (magnetic or non‐magnetic) metallic nano‐ and microlayers onto glass‐coated amorphous magnetic microwires. A suitable choice of magnetostrictive amorphous metallic nucleus, together with the specific stresses induced by the deposited layers, allows the tailoring of specific magnetic behavior. In this way, the preparation of multilayer microwires characterized either by square‐shaped hysteretic loops (typical of magnetically bistable microwires with longitudinal easy axes), or by nearly non‐hysteretic loops (for those microwires with a circumferential magnetization easy axes), can be achieved.     

Electron Spin Resonance Properties of Magnetic Granular GMI—Nanostructures in Millimeter Waveband

The millimeter waveband giant magnetoimpedance (GMI) and magnetoresonance (FMR) properties of thin-layered magnetic nanostructures are analyzed experimentally for wide temperature range. The correlation between FMR and GMI features are under discussion. The manifestation of the anisotropy established by the millimeter waveband FMR experiments and possible reasons of anisotropy appearance are given.     

射频磁控溅射法沉积非晶InGaZnO薄膜及真空退火对其性能的影响

采用RF磁控溅射法在石英玻璃上制备了InGaZnO薄膜,并对薄膜进行了真空退火实验,探讨了沉积过程中氧气流量及真空退火温度对薄膜的光学性质和电学性质的影响及其机理。测试结果表明薄膜的光透过率随氧气流的增加而增大,且当氧气流大于1cm3/min时,薄膜呈现出不导电性,在通入的氧气流为0.5cm3/min时迁移率达11.9cm2/(V·s)。经过真空退火后,氧气流小于1.5cm3/min时薄膜载流子浓度随退火温度的变化而变化;氧气流大于1.5cm3/min时样品由半绝缘性转变为半导电性。生长样品和退火样品均为n型半导体。     

Organic Solar Cells by Annealing Stacked Amorphous and Microcrystalline Layers

Organic solar cells were fabricated by stacking aromatic amine and C₆₀ layers. The energy conversion efficiency of these solar cells was low because of poor photoabsorption by these layers and short diffusion length of excitons. However, the photocurrent density was increased by about 3 times by the application of heat treatment to the stacked organic layers at 140 °C, and the maximum energy conversion efficiency reached 1.1 % under AM 1.5, 100 mW cm^–2 simulated solar light. The internal quantum efficiency of the photocurrent after the annealing reached about 45 %. When the aromatic amine layer was about 100 nm thick, the organic layers after the annealing showed a wrinkled structure under an optical microscope. The annealing temperature needed for the formation of this structure was in good agreement with the temperature needed for the increase in the photocurrent. The morphological change caused by the annealing was attributed to infiltration of the amorphous aromatic amine compound into grain boundaries of the microcrystalline C₆₀ layer, resulting in expansion of the C₆₀ layer and the wrinkled structure of the organic layers. From observation by electron microscopy, the mixed form of these two compounds near the interface was found to be suited to solar cells because the C₆₀ and aromatic amine phases wedge each other in a direction normal to two electrodes. However, the annealing slightly lowered photovoltage of the solar cell. This effect was attributed to a partial contact of the C₆₀ layer with a counter electrode through the aromatic amine layer.     

退火温度对CoTiO2微结构和磁特性的影响

为了研究在稀释磁性半导体CoTiO2薄膜中不同退火温度对薄膜结构和磁性的影响,通过磁控溅射方法和原位退火工艺制备了CoTiO2薄膜样品.然后利用扫描探针显微镜以及振动样品磁强计对所制得的薄膜样品磁性和微结构的变化进行了研究.研究发现,热处理温度对薄膜的微结构和磁性能有很大的影响.扫描探针显微镜对样品的微结构分析结果表明,在400 ℃时磁性相的分布比较均匀,Co掺杂到TiO2结构当中且没有Co颗粒或团簇;振动样品磁强计测量样品的磁性能结果显示该样品具有明显的室温铁磁性.     

Cd气氛退火对CdZnTe晶片质量影响

在CdZnTe晶体生长时,有时会产生大颗粒的沉积相,严重的影响了CdZnTe晶片的质量,通过电子探针测试证明其为Cd沉积相.采用Cd气氛退火来消除Cd沉积相,可以改善CdZnTe晶片的质量.实验发现:在较高的温度(600℃)条件下,退火可以有效的消除大颗粒(＞5 (m)的Cd沉积相,改善CdZnTe晶片红外透过率、X射线双晶回摆曲线半峰宽(FWHM)和腐蚀坑密度(EPD).在此条件下对CdZnTe晶片进行退火,有助于提高CdZnTe晶片的性能.     

退火对非晶态碲镉汞薄膜微结构和光敏性的影响

对射频磁控溅射生长的非晶态碲镉汞(a-MCT)薄膜在真空状态下进行退火,并通过X射线衍射(XRD)技术指出原生及低于125℃退火后的MCT薄膜均为非晶态.采用双体相关函数g(r)和电学测试系统研究了退火对a-MCT薄膜微结构和光敏性的影响.结果表明:经110℃,115℃和120℃退火后的a-MCT薄膜短程有序畴Rs由退火前的13.9 分别增大至17.9 、20.8 和26.2 ;光敏性则由原来的1.17,分别增加至退火后的2.01、2.67和4.25.     

Solid-phase Crystallization of Amorphous Silicon Films by Rapid Thermal Annealing

The morphous silicon films prepared by PECVD at substrate temperatures of 30℃ have been crystallized by rapid thermal annealing method, the budget of time-temperature in the annealing process is 600℃ for 120s, 850℃ for 120s, and 950℃ for 120s. The results indicate the crystallization at 850℃ and 950℃ are better as shown in micro-Raman scattering and scanning electronic microscope.     

Properties of p- and n-Type PbTe Microwires for Thermoelectric Devices

In thermopower measurements, microwires fabricated from as-purchased bulk PbTe exhibits p-type behavior between room temperature and ～600 K. At higher temperatures, it undergoes majority carrier inversion and exhibits n-type behavior. We report on the preparation and properties of potassium oxide and Zn-doped PbTe microwires, which exhibit stable p- and n-type behavior, respectively, between room temperature and 725 K. Thermoelectric figures of merit (ZT) are reported for device components prepared from bundles of such p- and n-type microwires in a glass matrix.     

电子束诱导沉积钴微米线及其铁磁性

通过电子束诱导沉积的方法制备了钴(Co)微米线,并利用扫描电子显微镜(SEM)、原子力/磁力显微镜(AFM/MFM)以及物性测量系统(PPMS)等手段对Co微米线的沉积尺寸、微结构、铁磁性和电学性质进行了测试和分析。研究结果表明:Co微米线轮廓清晰、均匀性好。在不同的沉积条件下,微米线的实际长度与设定长度基本一致;实际宽度数据呈类梯形分布,半高宽是设定值的2~10倍;实际厚度低于设定厚度的60%。沉积电流对Co微米线的铁磁特性有重要影响。当沉积电流大于0.5 nA时,样品呈现出良好的铁磁特性。另外,电学性能测试结果显示Co微米线呈现绝缘特性。成功制备了室温铁磁绝缘Co微米线,这将有助于深入开展微纳尺度的结构与器件的研究和应用。     

退火温度对PZT薄膜电容器性能的影响

通过简单的溶胶–凝胶法和快速热处理工艺,获得了在Pt/Ti/SiO2/Si基片上生长良好的PZT薄膜。制膜工艺简单,不需要回流和高温去结晶水,即可获得(111)择优取向的PZT薄膜。PZT薄膜经快速热处理在550~650℃退火,薄膜致密和平滑,均具有良好的铁电和介电特性,其最佳退火温度为600℃。     

非晶态As2S8半导体薄膜波导的热处理效应

研究了非晶态As2S8半导体薄膜在热作用下的结构变化效应.采用棱镜耦合技术、喇曼光谱测试技术,确认了As2S8薄膜经热处理后,薄膜密度增高和折射率增大的现象.实验表明,淀积态非晶As2S8半导体薄膜经紫外光饱和照射后,再经退火处理,当光折变在退火温度不低于160℃时,出现不完全可逆现象,可逆程度跟退火温度有关.实验显示,退火态非晶As2S8半导体薄膜在玻璃转化温度130℃时退火处理,光折变存在完全可逆现象.光传输实验显示,热处理后的非晶态As2S8半导体薄膜波导,其传输损耗减小了约4dB/cm.