Effect of film thickness on the evolution of annealing texture in sputtered copper films

Microstructural evolution during elevated temperature annealing of sputter deposited copper (Cu) films was investigated by electron backscatter diffraction (EBSD). Analysis of films was performed both in situ using a heating stage, and by ex-situ observation of microstructural evolution. It was noted that not only is the Cu film texture and grain size a function of film thickness, but also that the fraction of twin boundaries present in the material is strongly dependent upon film thickness. This is explained by means of a simple model that considers the energy of the system. Surface and interface energies, as well as grain boundary energies for random high angle boundaries and for twin boundaries (both coherent and incoherent planes) are used in the determination. The model was shown to accurately predict the twin boundary size in self-annealed films. This type of analysis also results in a texture map similar to that presented by Thompson,¹² but incorporates the development and effect of twin boundaries, so that additional texture components (in addition to 111 and 100 fibers) are included.     

Si基GaN薄膜的制备方法及结构表征

分别采用射频磁控溅射、热壁化学气相沉积(CVD)、电泳沉积法制备GaN薄膜。利用扫描电镜(SEM)、荧光光谱仪对样品进行结构、形貌和发光特性的分析比较。射频磁控溅射方法中,把SiC中间层沉淀到Si衬底上,目的是为了缓冲由GaN外延层和Si衬底的晶格失配造成的应力。结果证实了SiC中间层提高了GaN薄膜的质量。热壁化学气相沉积法制备GaN晶体膜时,选择H2作反应气体兼载体,有利于GaN膜的形成。电泳沉积法显示所得样品为六方纤锌矿结构的GaN多晶薄膜。结果表明:溅射法制备的GaN薄膜结晶效果好;CVD法制备时GaN薄膜应用范围广;电泳沉积法操作方便、简单易行。     

The Zn(S,O,OH)/ZnMgO buffer in thin‐film Cu(In,Ga)(Se,S)2‐based solar cells part II: Magnetron sputtering of the ZnMgO buffer layer for in‐line co‐evaporated Cu(In,Ga)Se2 solar cells

A ZnS/Zn_1‐xMg_xO buffer combination was developed to replace the CdS/i‐ZnO layers in in‐line co‐evaporated Cu(In,Ga)Se₂(CIGS)‐based solar cells. The ZnS was deposited by the chemical bath deposition (CBD) technique and the Zn_1‐xMg_xO layer by RF magnetron sputtering from ceramic targets. The [Mg]/([Mg] + [Zn]) ratio in the target was varied between x = 0·0 and 0·4. The composition, the crystal structure, and the optical properties of the resulting layers were analyzed. Small laboratory cells and 10 × 10 cm² modules were realized with high reproducibility and enhanced stability. The transmission is improved in the wavelength region between 330 and 550 nm for the ZnS/Zn_1‐xMg_xO layers. Therefore, a large gain in the short‐circuit current density up to 12% was obtained, which resulted in higher conversion efficiencies up to 9% relative as compared to cells with the CdS/i‐ZnO buffer system. Peak efficiencies of 18% with small laboratory cells and 15·2% with 10 × 10 cm² mini‐modules were demonstrated. Copyright © 2009 John Wiley & Sons, Ltd.     

Dirty RF: A New Paradigm

The implementation challenge for new low-cost low-power wireless modem transceivers has continuously been growing with increased modem performance, bandwidth, and carrier frequency. Up to now we have been designing transceivers in a way that we are able to keep the analog (RF) problem domain widely separated from the digital signal processing design. However, with today’s deep sub-micron technology, analog impairments – “dirt effects” – are reaching a new problem level which requires a paradigm shift in the design of transceivers. Examples of these impairments are phase noise, non-linearities, I/Q imbalance, ADC impairments, etc. In the world of “Dirty RF” we assume to design digital signal processing such that we can cope with a new level of impairments, allowing lee-way in the requirements set on future RF sub-systems. This paper gives an overview of the topic and presents analytical evaluations of the performance losses due to RF impairments as well as algorithms that allow to live with imperfect RF by compensating the resulting error effects using digital baseband processing.     

Ku波段便携设备射频单元测试架的设计与实现

随着卫星通信的发展,高频段和高集成的卫星设备被广泛使用,在设备出现故障时,操作人员无法科学判断设备故障在于射频部分还是在于主机部分。在分析和研究Ku波段便携站射频设备的基础上,详细介绍了利用微波技术和高频电子器件研制的一个不对设备造成危险或者危害且能快速、准确测量判断Ku波段便携站射频单元的测试架的设计与实现过程。     

How r-Plane Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Surface Modifications Impact the Growth of Epitaxial (001) CeO<Subscript>2</Subscript> Thin Films

We present evidence that it is the presence or absence of atomic terraces with a specific crystallographic orientation on the (102) Al₂O₃ surface that promotes growth of single-crystal (001) CeO₂ films over polycrystalline (111) CeO₂ films. The CeO₂ film nucleates so that the [010] and [100] directions of the film align parallel and perpendicular to the terrace edges. In the absence of terraces, multidomain (111) CeO₂ films result in which the in-plane orientation of the two domains are rotated by 85.71°, so that a [110] CeO₂ direction aligns parallel to either the or Al₂O₃ direction.     

基于MRF24J40的IEEE802．15．4无线收发电路设计

采用MRF24J40构成的IEEE802.15.4无线收发器电路,为IEEE802.5.15.4MAC和PHY物理层提供硬件层,支持MiWiTM、ZigBee协议和其他协议,工作在2.405~2.48 GHz ISM频段,接收灵敏度为-91 dBm,发射输出功率为 0 dBm,发射功率控制范围为38.75 dB,电源电压范围为2.4~3.6 V,睡眠模式电流消耗为2μA。采用4线式SPI与微控制器接口,适合家居自动化、工业自动化等低数据速率传输的应用。     

Effects of substrate temperature on the efficiency of hydrogen incorporation on the properties of Al-doped ZnO films

Al-doped ZnO (AZO) transparent conducting films were successfully prepared on glass substrates by RF magnetron sputtering at different substrate temperatures in Ar and H₂ + Ar sputtering ambient. The effects of substrate temperature on the effectiveness of hydrogen incorporation in Al-doped ZnO films were investigated. The microstructural, electrical and optical properties of AZO films were systematically analyzed by surface profiler, X-ray diffractometry, scanning electron microscope, four-point probe measurement and UV/vis spectrophotometer. The XRD patterns and SEM pictures indicate that the crystallinity of AZO thin films was markedly improved with hydrogen incorporation at low substrate temperature, while the improvement of crystallinity was not an obvious change at high substrate temperature. The results also indicate that hydrogen incorporation has the stronger effectiveness on the transparent conductive properties of AZO films with the substrate temperature decreasing. The resistivity of the films decreases, especially for lower substrate temperatures, due to the incorporation of hydrogen atoms. These results suggest that substrate temperature should be controlled to the lower level to effectively reduce resistivity without detriment to transmittance of AZO thin films when hydrogen is incorporated.     

Mössbauer effect studies of Fe–C combinatorially sputtered thin films

Alloys of Fe_{1? x} C _x were produced using combinatorial sputtering methods. The composition of the films as a function of position was determined using electron microprobe techniques and the results have shown that a composition range of about 0.35?<?x?<?0.75 was obtained. X-ray diffraction methods were employed to study the structure of the thin films and showed that all portions of the films were amorphous or nanostructured. Room temperature ⁵⁷Fe Mössbauer spectroscopy was utilized to study the atomic environment around the Fe atoms. Hyperfine field distributions of ferromagnetic alloys, as extracted from the Mössbauer analysis, suggested the existence of two classes of Fe sites: (1) classes of Fe sites that have primarily Fe neighbours corresponding to a high-field component in the distribution and (2) classes of Fe sites that have a greater number of C neighbours, corresponding to a low-field component. The magnetic splitting decreased as a function of increasing carbon concentration and alloys with x greater than about 0.68 were primarily paramagnetic in nature. These spectra exhibited distributions of quadrupole splitting with mean splitting in excess of 1.0?mm/s. This indicates a higher degree of local asymmetry around the Fe sites than typically seen in other Fe-metalloid systems.     

Ionenstrahlätzen – Verfahren und Ausrüstungen für die Mikrostrukturierung

Ion beam techniques are widely used jur modification as well us analysis of materials in development and production of VLSI circuits and their importance is continuously increased in course of the reduction of structure dimensions. Some possibilities and problems connected with the application of ion beams of low energy in the pattern transfer are- described and the stage of development achieved in the Central Institute of Isotope and Radiation Research is outlined.