On the application of the Kramers-Kronig relations to problems concerning the frequency dependence of electrode impedance

It is emphasized that, under certain conditions, the frequency dependences of the real and imaginary parts of an electrical impedance are correlated by the Kramers-Kronig relations. The importance of these relations in electrochemistry is illustrated by the examples of certain electrochemical impedance types. Some misapprehensions appearing in the electrochemical literature are pointed out.     

Study of electron traps in the thin interfacial oxide layer of Al-, Au- and Sn-n GaAs Schottky barriers by detrapping experiments

Electron traps in MIS-type Schottky barriers on n-GaAs were investigated by measuring the change of the flat-band voltage, due to detrapping, as a function of time. The trap depth and the capture cross section for a particular trap were obtained from the temperature dependence of the time constant for detrapping. It was found that the detrapping process in some cases is a two-state thermionic emission and tunneling process. For other trapping levels the results indicated clearly that the mechanism was different from the thermionic emission and tunneling process.     

Ni/Pd/Si固相反应及NiSi热稳定性增强研究

研究了Ni/Pd双层薄膜在硅衬底上的硅化物形成过程.结果表明,加入Pd层后,退火形成Ni1-xPdxSi固熔体,该固熔体比NiSi的热稳定性好,使得NiSi向NiSi2的转变温度升高.加入Pd的量越多,NiSi2的成核温度越高,并用经典成核理论解释了该现象.     

掺Pt对Si(100)上形成的NiSi薄膜应力的影响

利用在线应力测试技术表征了掺入Pt后对镍硅化物薄膜应力性质的影响.通过改变NiSi薄膜中Pt含量以及控制热处理的升温、降温速率实时测量了薄膜应力,发现在Si(100)衬底上生长的纯NiSi薄膜和纯PtSi薄膜的室温应力主要是热应力,且分别为775MPa和1.31GPa,而对于Ni1-xPtxSi合金硅化物薄膜,室温应力则随着Pt含量的增加而逐渐增大.应力随温度变化曲线的分析表明,Ni1-xPtxSi合金硅化物薄膜的应力驰豫温度随Pt含量的增加,从440℃(纯NiSi薄膜)升高到620℃(纯PtSi薄膜).应力驰豫温度的变化影响了最终室温时的应力值.     

In-situ X-ray Diffraction study of Metal Induced Crystallization of amorphous silicon

By covering amorphous silicon (a-Si) with a thin metal film, it is possible to lower the crystallization temperature of the a-Si (typically around 800 °C when using ramp anneals) to levels which can be used in a manufacturing process. This phenomenon of Metal Induced Crystallization (MIC) has been reported previously for Ni, Au and Al. In this work, in-situ X-ray Diffraction was used to study the MIC process for 20 different metals (Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Al). The 7 metals which lower the crystallization temperature the most are Ni, Pt, Pd, Cu, Au, Al and Ag. The crystallization kinetics were studied in detail for these 7 materials. In order to explain the MIC process, two models where used depending on the interaction of the metal with Si (eutectic or compound forming).     

A genetic polymorphism of the peroxisome proliferator-activated receptor gamma gene influences plasma leptin levels in obese humans

OBJECTIVE: To determine whether adverse perinatal outcome is associated with asthma or asthma medication use during pregnancy. METHODS: A retrospective cohort study was conducted of women who resided in Halifax County, Nova Scotia, and delivered between 1991 and 1993. Asthmatic women were classified into three groups, according to medication usage: no medications, beta agonists only, and steroids with or without other asthma medications. Outcomes compared among asthmatic and nonasthmatic women included maternal complications (pregnancy-induced hypertension, cesarean delivery, gestational diabetes, preterm birth, and antepartum and postpartum hemorrhage) and neonatal outcomes (low birth weight, congenital malformations, hyperbilirubinemia, and respiratory distress syndrome). RESULTS: The cohort included 817 asthmatic women and 13,709 nonasthmatic women. Overall, the prevalence of pregnancies complicated by asthma increased from 4.8% in 1991 to 6.9% in 1993. Asthmatic women were at increased risk for antepartum and postpartum hemorrhage, independent of medication usage. Asthmatic women taking steroids were at increased risk for pregnancy-induced hypertension (odds ratio [OR] 1.7; 95% confidence interval [CI] 1.0, 2.9). The only significant difference in neonatal outcome between asthma medication groups and nonasthmatic women was of an increased risk of hyperbilirubinemia in infants of women taking steroids (OR 1.9; 95% CI 1.1, 3.4). CONCLUSION: Risk of antepartum and postpartum hemorrhage is increased in asthmatic women, independent of medication usage. The increased incidence of neonatal hyperbilirubinemia and the borderline increased risk of pregnancy-induced hypertension may be complications of steroid use or may be related to poorly controlled asthma.     

用弹道电子显微术研究Co-Ti-Si系统的退火温度对CoSi2/Si势垒不均匀性的影响

通过在硅(100)衬底上淀积的Co(3nm)/Ti(1nm)双金属层在不同退火温度下的固相反应,在硅衬底上制备了超薄外延CoSi2薄膜.在低温下,用弹道电子显微术(BEEM)及其谱线(BEES)测量了CoSi2/Si接触的局域肖特基势垒高度.对于800℃退火的CoSi2/Si接触,势垒高度的空间分布基本符合高斯分布,其峰值在599meV,标准偏差为21meV.而对于700℃退火样品,势垒高度分布很不均匀,局域的势垒高度值分布在152meV到870meV之间,这可归因于CoSi2薄膜本身的不均匀性.     

In situ X-ray diffraction study of thin film Ir/Si solid state reactions

The solid state reaction between a thin (30 nm) Ir film and different Si substrates (p-type Si(1 0 0), n- and p-type Si(1 1 1), silicon on insulator (SOI) and polycrystalline Si) was studied using a combination of in situ X-ray diffraction (XRD), in situ sheet resistance and laser light scattering measurements. No significant influence of either the dopants or the substrate orientation was detected as a phase formation sequence of IrSi, Ir₃Si₄,Ir₃Si₅ and IrSi₃ was found for all samples. The presence of a thin (<4 nm) amorphous IrSi film at room temperature and its subsequent crystallization could be deduced from the appearance of a broad semi-amorphous diffraction peak in the XRD spectrum around 400 °C. The results were verified using ex situ Rutherford Backscattering Spectroscopy, Scanning Electron Microscopy and 4-point probe measurements on quenched samples. The activation energy of the crystallization process and the silicide growth was determined using a Kissinger analysis on ramp anneals with different ramp rates. In addition, the influence of up to 25 volumetric % (20.5 atomic %) of Ir to the silicide formation in the Ni/Si system was studied on SOI and polycrystalline Si substrates. In the presence of Ir, the temperature range over which the low resistivity NiSi exists, is reduced both through an increase in formation temperature and an earlier consumption by the formation of NiSi₂. After the heat treatment, a continuous distribution of Ir throughout the NiSi₂ phase was detected using X-ray photoelectron spectroscopy depth profiling. A low sheet resistance of was maintained on both substrates up to 900 °C.     

In situ and ex situ investigation on the annealing performance of the ZnO film grown by ion beam deposition

The effects of the post-annealing treatment on the properties of the ZnO thin films deposited by ion beam sputtering have been investigated. By using in situ X-ray diffraction technique, an overview of the crystallization behavior of the ZnO film during the annealing process was obtained. It was found that the whole process can be divided into three regions. The improvement of the film’s crystallinity performance mainly occurs within the annealing temperature ranging from 300 to 600 °C. Both in situ and ex situ XRD results show the shift of the ZnO (002) peak towards high angle with the increasing annealing temperature, which is attributed to the variation of the stress in the film. The stress is mainly caused by the intrinsic stress which is affected by the oxygen deficiency in the film. The oxygen deficiency is sensitive to the annealing ambient. The film annealed in the O₂ ambient has less oxygen deficiency and higher resistivity. All the ZnO films deposited on the glass substrates have an optical transmittance over 85% in the visible region. Our results show that the ZnO films deposited using ion beam sputtering exhibit good thermal stability and high performance after annealing.     

Digital Predistortion for 5G Small Cell: GPU Implementation and RF Measurements

In this paper, we present a high data rate implementation of a digital predistortion (DPD) algorithm on a modern mobile multicore CPU containing an on-chip GPU. The proposed implementation is capable of running in real-time, thanks to the execution of the predistortion stage inside the GPU, and the execution of the learning stage on a separate CPU core. This configuration, combined with the low complexity DPD design, allows for more than 400 Msamples/s sample rates. This is sufficient for satisfying 5G new radio (NR) base station radio transmission specifications in the sub-6 GHz bands, where signal bandwidths up to 100 MHz are specified. The linearization performance is validated with RF measurements on two base station power amplifiers at 3.7 GHz, showing that the 5G NR downlink emission requirements are satisfied.