溅射法制备钇掺杂铟锌氧薄膜和器件特性研究王丹丹,王卿璞*,王汉斌,张锡健,武丽伟,李福杰,袁帅中国,济南,山东大学物理学院

室温下,采用射频磁控溅射法分别在钠钙玻璃和P型硅衬底上制备了不同厚度的钇掺杂铟锌氧薄膜。研究了薄膜的结构形貌和光学特性。以P型硅为栅极制备了底栅结构的YIZO薄膜晶体管,并研究了器件的输出和转移特性。研究发现,室温下制备的所有Y掺杂IZO薄膜均为非晶结构,YIZO薄膜晶体管均为n沟道耗尽型器件。有源层厚度为20nm的器件的开关电流比超过105,亚阈值摆幅为2.20 V/decade,阈值电压为-1.0V, 饱和迁移率为0.57 cm2/ V·s。     

Nonlinear microwave signal-processing devices using thin ferrimagnetic films

The signal-processing characteristics of signal-to-noise enhancers and frequency-selective limiters are described. Performance of several practical devices is discussed. The theory of below-threshold operation is reviewed. New theoretical results are presented for calculation of threshold power and above-threshold power loss. Frequency selectivity and the consequences of linear losses are calculated for the limiter.This work was performed in part under USAF Contract F33615-81-C-1431.     

Evaporated InSb thin films and their application to bubble domain devices

Indium antimonide thin films were deposited by the three-temperature method onto various kinds of amorphous substrates such as Corning 7059 glass using source materials of 99.9999 % purity. The optimum ratio of vapor pressures of indium and antimony, and the optimum temperature of the substrate, T_sub, were investigated for each substrate in order that the deposited film had the highest carrier mobility, μH, and Hall coefficient, R_H, as well as being perfectly stoichiometric when tested by the x-ray diffraction method. The microstructure of the films was also investigated as a function of T_sub. The thickness of the film varied between 1.0 – 3.2 μm. Among the films thus obtained the best one gave the characteristics of μ_H = 23,000 cm²/V·sec and R_H = 480 cm₃/C at room temperature. The latter value is entirely the same as that of the purest bulk material. This film was photo—etched to a cross—shaped Hall detector; the width of both the current lead and the output lead was 4μm. The device was applied to the detection of magnetic bubble domains of 10 μm diameter. The output voltage of 1.4 mV is larger than those ever reported for a bubble of the same order of diameter.     

Structure and soft magnetic properties of Fe-Co-Ni-based multicomponent thin films

Soft magnetic thin films with suitable uniaxial anisotropy and high saturation magnetization are required for high frequency applications, since the ferromagnetic resonance frequency (f_FMR) is proportional to the multiplication of the saturation magnetization and anisotropy magnetic field. In this study, multicomponents of Fe-Co-Ni-based soft magnetic thin films were deposited on the Si substrate by radio frequency (RF) magnetron sputtering with various Ar/N₂ ratios at room temperature. The composition, crystal structure, surface morphology, and magnetic domain were analyzed. Without nitrogen doping, the domain of the magnetic thin film was arranged randomly. The effect of N₂ content in the thin film on the magnetic properties was evaluated and further discussed. Magnetic properties, including saturation magnetization (M_s) and coercivity (H_c), were determined. The saturation magnetization of the undoped magnetic thin film was around 1.3 T. However, when the nitrogen was added, the magnitude of the anisotropy field could reach 30 Oe, while the saturation magnetization was around 1 T. It is expected that the derived magnetic thin film is a promising candidate for potential usage in high frequency inductors.     

Al-doped ZnO and N-doped CuxO thermoelectric thin films for self-powering integrated devices

With the use of a thermoelectric material, terrestrial heat can be harvested then converted to electrical power. The advent of these devices has led to the idea of self-powering wherein devices are driven by heat from their working environment. The focus of this study is to fabricate low cost thermoelectric materials, such as aluminum-doped ZnO (ZnO:Al) and nitrogen-doped Cu_xO (Cu_xO:N) that can effectively harvest heat for power generation.ZnO:Al (n-type) and Cu_xO:N (p-type) thin films with nanocrystallites were deposited in (1.27×0.64) cm² glass substrates via spray pyrolysis technique. These materials exhibit significantly high thermoelectric properties, which is comparable to previous works on thermoelectric materials. ZnO:Al showed to have a maximum Seebeck coefficient (S) of 448 μV/K ranging from 300 to 330 K. Cu_xO:N exhibited a significantly much larger |S| of 1002 μV/K at the same temperature range. A prototype of a thermoelectric device was constructed based from these grown thin films and showed to generate a maximum of 32.8 mV at 28 K temperature difference.     

Microstructure and magnetic properties of In1−xCrxN thin films

Microstructure and magnetic properties of In_1−xCr_xN thin films grown on GaN-on-sapphire templates by molecular beam epitaxy are investigated. Optimized growth conditions are identified for the In_1−xCr_xN thin films at reduced growth temperature. The In_1−xCr_xN thin films on the top of the InGaN buffer layers exhibit high crystalline-quality. The magnetic properties of In_1−xCr_xN thin films show a ferromagnetic behavior even at room temperature.     

Surface plasmon polaritons in thin metal films and their role infiber optic polarizing devices

The polarization-selective evanescent field coupling of an optical wave in a 1.3-μm, fiber to surface, plasmon polaritons supported by a thin aluminium film was investigated theoretically and experimentally. Good agreement was observed between the theoretically predicted conditions for efficient coupling and the experimentally determined conditions for high TM/TE extinction ratio of the optical field. The use of silver and chrome in place of aluminum was investigated experimentally at 1.3 μm, and 0.63-μm devices using aluminium were also studied. The results led to the realization of readily manufacturable, high-extinction-ratio (>50 dB) low-loss (<0.5 dB) fiber optic polarizers and polarizing couplers in standard and highly birefringent fiber     

Multiscale simulation of aluminum thin films for the design of highly-reliable MEMS devices

A multiscale simulation methodology is presented to predict the macroscopic mechanical properties of aluminum thin films with a columnar grain structure from the morphology at microscopic scale. The elasto–plastic characteristics of the thin films are calculated as a function of the grain size, temperature, and strain rate by taking into account creep phenomena. The simulated data are validated by experimental stress–strain curves measured by dedicated microstructures in conjunction with a nanoindentation test equipment.     

Directional coupling of magnetostatic surface waves in layered magnetic thin films

The propagation characteristics of magnetostatic surface waves (m.s.s.w.) in a layered system of y.i.g. film, dielectric, y.i.g. film, are theoretically investigated. It is shown that the directional coupling of m.s.s.w. is possible between y.i.g. films. The directional coupling has frequency filtering characteristics due to dispersion of m.s.s.w.     

电镀法制备CoNiMnP永磁薄膜研究

采用电子能谱仪(EDS)与振动样品磁强计(VSM),研究了电流密度及镀液pH值对电镀CoNiMnP永磁薄膜矫顽力的影响。结果表明:CoNiMnP永磁薄膜具有明显的垂直各向异性,且随电流密度和镀液pH值的增大,CoNiMnP薄膜的矫顽力呈先增大后降低的变化;当电流密度为5×10–3A/cm2、镀液pH值为5时,CoNiMnP薄膜垂直方向的矫顽力Hcj达到最大值80kA·m–1。     

适用SAW器件的ZnO/Ti/Si薄膜制备及缺陷分析

在Si(100)衬底和Ti/Si(100)衬底上分别制备了ZnO薄膜,探讨了Ti缓冲层对ZnO薄膜结构和缺陷的影响,利用X射线衍射(XRD)测试了ZnO薄膜的晶体结构及择优取向,利用原子力显微镜(AFM)观察ZnO薄膜的表面粗糙度(RMS),利用光致发光(PL)光谱检测了ZnO薄膜的缺陷,利用四探针法测试了ZnO薄膜的电阻率。结果表明,在Ti/Si(100)衬底上、衬底温度350℃的条件下,制备的ZnO薄膜表面光滑、缺陷少、电阻率高且具有高C轴取向。本文这一工作对于压电薄膜缺陷分析及高性能ZnO的声表面波(SAW)器件研制有重要意义。     

集成光学器件的PLZT薄膜溶胶-凝胶法制备与性能研究

在掺铌钛酸锶(NST)的衬底上, 通过加入抑制开裂剂聚乙二醇对异辛基苯基醚(triton X-100), 利用溶胶-凝胶法制备了厚达4.6μm的 锆钛酸铅镧(PLZT)薄膜,从而有效地减小了其在集成光学器件应用中的传输损耗。实验分析 了triton X-100的加入量对薄膜质量的影响,并通过优化triton X-100的加入量可有效抑制薄 膜开裂。利用光学显微镜、扫描电子显微镜(SEM)、X射线衍射仪(XRD)、棱镜耦合波导 测试仪和台阶 仪等对制备的薄膜性能进行分析。结果表明,经过650℃快速退火处 理后,得到了表面平整度小于30nm、 粒径为50~100nm的钙钛矿结构PLZT薄膜,测得PLZT(8/65/35)和PL ZT(11/65/35)薄膜在 1550nm波长处的折射率分别为2. 4029和2.388。本文方法制备的 薄膜可以用于PLZT电光器件的制作。     

磁场退火对FePt/Ag薄膜磁性能的影响

采用磁控溅射法室温沉积获得FePt/Ag薄膜,然后在500℃下,于真空磁退火炉中对薄膜进行退火处理。利用XRD和振动样品磁强计(VSM),研究了磁场退火对薄膜结构和磁性能的影响。结果表明,500℃零磁场退火获得了矫顽力为0.763 4 MA.m–1、平均晶粒尺寸21 nm的L10-FePt薄膜。磁场提供了FePt成核生长的驱动力,0.8 MA.m–1磁场退火后FePt的平均晶粒尺寸为26 nm,矫顽力增大至0.804 3 MA.m–1。非磁性Ag的掺杂可有效抑制磁性FePt晶粒的团聚生长。     

The conductivity and magnetic properties of zinc oxide thin films doped with cobalt

The magnetic properties, temperature dependences of the resistivity, Hall constant, and magnetoresistance of epitaxial zinc oxide films doped with cobalt are studied. The ferromagnetism of the films is observed at room temperature. The conduction and magnetoresistance of the films are attributed to transport of electrons in the conduction band at high temperatures and to hopping transport at low temperatures. With increasing concentration of cobalt dopants, the resistivity of the films increases and the concentration of electrons decreases. This is due to the increase in the ionization energy of donor states because of the increase in the energy of exchange interaction between electrons at donor states and electrons of the d shell of cobaltions.     

Microstructures in CoPtC magnetic thin films studied by superpositioning of micro-electron diffraction

Cross-sectional transmission electron microscopy observation of CoPtC thin films showed that 10 nm sized ultrafine particles of CoPt typically were elongated along the substrate normal. Analysis of the superposition of 40 micro-electron diffraction patterns showed that there was no preferred crystal orientation of CoPt particles. This superpositioning technique can be applied to thin films, whose X-ray diffraction analysis is difficult due to the small size of the crystals.     

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%。     

Influence of Mn-doping concentration on the microstructure and magnetic properties of ZnO thin films

The microstructure and magnetic properties of Mn-doped ZnO films with various Mn contents, synthesized by magnetron sputtering at room temperature, are investigated in detail. X-ray diffraction (XRD) measurement results suggest that the doped Mn ions occupy the Zn sites successfully and do not change the crystal structure of the ZnO films. However, the microstructure of the Mn-doped ZnO films apparently changes with increasing the Mn concentration. Arrays of well-aligned nanoscale rods are found in the Mn-doped ZnO films with moderate Mn concentrations. Magnetic measurement results indicate that the ZnO films doped with moderate Mn concentration are ferromagnetic at room temperature. The possible origin of the ferromagnetism in our samples is also explored in detail.     

高密存储介质磁性纳米颗粒薄膜与纳米超晶格结构研究进展(英文)

钴基合金和铁基合金磁性纳米颗粒薄膜和纳米超晶格结构,由于具有较高的矫顽力和各向异性能,较小的粒子尺寸分布和能形成“单域”结构等特性,从而成为颇有潜力的高密存储介质。最近几年,人们竞相研究其制备方法,其中主要包括真空淀积法、液相化学合成法和离子注入法等,采用各种措施来提高存储介质的热稳定性和其他磁学性能,并取得巨大进展。