High mobility,low voltage polymer transistor

We introduce a polymer transistor that operates with low supply voltage and yet has a field-effect mobility higher than the mobilities reported for low voltage polymer transistors. A simple plasma oxidation of the gate metal to form a thin (3.74 nm) top metal oxide layer in the gate metal is involved in the fabrication that acts as the gate dielectric. With ultrathin gate dielectrics, the variation in the dielectric thickness and the surface roughness scattering can severely limit the mobility attainable. The plasma oxidation under certain conditions produces a very smooth oxide surface, leading to the high mobility.     

碱性阻挡层抛光液中ULK介质抛光性能的研究

研究了化学机械抛光(CMP)过程中抛光液的SiO₂磨料质量分数和表面活性剂对多孔SiOCH薄膜(ULK介质)介电常数(k)及抛光速率的影响。所用抛光液(pH=10)主要由0%~4%(质量分数,下同)SiO₂、0.075%H₂O₂、1%邻苯二甲酸氢钾和不同质量浓度的表面活性剂组成,其中表面活性剂为非离子表面活性剂脂肪醇聚氧乙烯醚(AEO-9和AEO-15)、阴离子表面活性剂十二烷基硫酸铵(ADS)和两亲性非离子表面活性剂辛基苯酚聚氧乙烯醚(OP-50)。结果表明,磨料质量分数的增大会使ULK介质的去除速率和k值都增大。聚醚类表面活性剂都能在CMP过程中很好地保护ULK介质表面,降低其去除速率,OP-50的效果尤其好。当采用2%SiO₂+0.075%H₂O₂+1%KHP+200 mg/L OP-50的抛光液进行CMP时,ULK介质的去除速率为5.2 nm/min,k值增幅低于2%,Cu和Co的去除速率基本不变。     

光催化氧化对GaN 材料腐蚀电化学及化学机械抛光的影响

考察了氮化镓(GaN)晶片在不同质量分数和pH的溴酸钾(KBrO3)溶液中的腐蚀电化学行为。结果显示,GaN在溴酸钾质量分数为1%时腐蚀电位最低。在此基础上使用光催化氧化法能够显著降低腐蚀电位,使GaN材料的腐蚀速率进一步提高。CMP实验结果显示:紫外光(UV)的加入使GaN在1%KBrO3溶液(pH=4)中的抛光速率提高,而再加入光催化剂二氧化锡(SnO2)会使得GaN材料的抛光速率进一步提高。当KBrO3质量分数为1%,pH=4时加入紫外光和0.2%(质量分数)SnO2,GaN材料的抛光速率可达502.4 nm/h,抛光后晶片表面的均方根粗糙度为0.11 nm。     

HZSM5分子筛膜复合二氧化锡对甲烷的气敏性能研究

采用液相氧化法制备二氧化锡纳米颗粒,并利用浸渍法制备Pd负载二氧化锡纳米材料,通过丝网印刷得到气敏传感膜并在其表面印刷分子筛层。基于动态气敏测试系统探究传感器对甲烷气体的灵敏度及其在CO和乙醇干扰气体下的选择性。研究结果表明,在Pd-SnO₂敏感层表面印刷Pd-HZSM5层后,传感器对甲烷的响应能力显著提高,并且在体积分数为5×10^-4的CO存在时,对甲烷的选择性也得到明显的提升。同样,在质量分数为2×10^-5乙醇的存在下,传感器对甲烷的响应也没有受到干扰。通过对分子筛进行表征和催化分析,发现Pd-HZSM5对CO的催化效率可达100%,使得CO在扩散过程中被催化氧化,这可能是印刷Pd-HZSM5分子筛膜从而提高传感器选择性的主要原因。同时研究还表明,在敏感层表面印刷分子筛层并不会影响传感器的响应和恢复速率。     

一种高性能FPGA辐射发射抑制方法研究

随着半导体技术的不断发展,集成电路的电路速度、集成密度和I/O端口数量已大大增加,FPGA的小型化、高密度集成会引发电磁兼容性的问题,电磁屏蔽是抑制电磁辐射最有效的方法,选择高效的电磁屏蔽材料可以取得良好的屏蔽效果。而目前电磁屏蔽材料在FPGA上的应用较少,因此选取了一款具有代表性的高性能FPGA作为研究对象,通过近场扫描测试来研究不同状态下FPGA的电磁辐射发射问题;针对芯片的特点,选取了复合金属屏蔽罩和吸波导电海绵作为电磁屏蔽材料,对FPGA的辐射发射进行抑制。进一步的实验结果表明,由金属材料复合而成的屏蔽罩具有更好的屏蔽效能,达到了10 dBm,相比之下,吸波导电海绵的压缩性和结构稳定性更有助于FPGA在多场景下应用。     

Synthesis of SnAgCu nanoparticles with low melting point by the chemical reduction method

SnAgCu alloy with low melting point and good soldering property is a good candidate for the Sn/Pb eutectic. In this paper, SnAgCu nanoparticles were synthesized by a chemical reduction method. The particle size and the melting point are controlled by modifying the process parameters, including reaction temperature, surfactant concentration and dropping speed of precursor. The lowest melting onset temperature is observed at 199.1 °C, which is 18 °C lower than that of commercially available SnAgCu solder alloy. The tensile strength of the as-synthesized reaches 34.3 MPa, which reveals a good solderability property.     

Diode-pumped medium-aperture-size square Nd,Y:CaF2 rod amplifier for Inertial Confinement Fusion laser drivers

We demonstrate, for the first time, an 12 mm × 12 mm 0.5%Nd,5% Y:CaF₂ crystal rod having a uniformly-distributed fluorescence spectrum and capable of operating as an amplifying medium at high repetition frequencies. A small gain of 2.7 is experimentally achieved at repetition frequency of 10 Hz for a pump center wavelength of 802 nm, power and absorption efficiency, 61.2 kW and 63.7%, respectively. Spatial-uniformity degradation of the output near-field beam distribution is observed, which should be attributed to the inhomogeneity of Nd,Y:CaF₂ crystal. For a pump power of 61.2 kW, the stored energy of Nd,Y:CaF₂ amplifier is 3.73 J. When the input energy is 50 mJ, the output laser energy is 1.4 J of extraction efficiency up to 37.53% after four-pass amplification.     

Thermal stability of devices with molybdenum oxide doped organic semiconductors

We demonstrate the thermal stability of transition-metal-oxide (molybdenum oxide; MoO₃)-doped organic semiconductors. Impedance spectroscopy analysis indicated that thermal deformation of the intrinsic 1,4-bis[N-(1-naphthyl)-N′-phenylamino]-4,4′-diamine (NPB) layer is facilitated when the MoO₃-doped NPB layer is deposited on the intrinsic NPB layer. The resistance of the intrinsic NPB layer is reduced from 300 kΩ to 3 kΩ after thermal annealing at 100 °C for 30 min. Temperature-dependent conductance/angular frequency–frequency (G/w-f-T) analysis revealed that the doping efficiency of MoO₃, which is represented by the activation energy (E_a), is reduced after the annealing process.     

Time–frequency interpretation of multi-frequency signal from rotating machinery using an improved Hilbert–Huang transform

The Hilbert–Huang transform (HHT) has proven to be a promising tool for the analysis of non-stationary signals commonly occurred in industrial machines. However, in practice, multi-frequency intrinsic mode functions (IMFs) and pseudo IMFs are likely generated and lead to grossly erroneous or even completely meaningless instantaneous frequencies, which raise difficulties in interpreting signal features by the HHT spectrum. To enhance the time–frequency resolution of the traditional HHT, an improved HHT is proposed in this study. By constructing a bank of partially overlapping bandpass filters, a series of filtered signals are obtained at first. Then a subset of filtered signals, each associated with certain energy-dominated components, are selected based on the maximal-spectral kurtosis–minimal-redundancy criterion and the information-related coefficient, and further decomposed by empirical mode decomposition to extract sets of IMFs. Furthermore, IMF selection scheme is applied to select the relevant IMFs on which the HHT spectrum is constructed. The novelty of this method is that the HHT spectrum is just constructed with the relevant, almost monochromatic IMFs rather than with the IMFs possibly with multiple frequency components or with pseudo components. The results on the simulated data, test rig data, and industrial gearbox data show that the proposed method is superior to the traditional HHT in feature extraction and can produce a more accurate time–frequency distribution for the inspected signal.     

Investigations on immunity of interfaces between intelligent media processor and DDR3 SDRAM memory

Due to the complexity of IC, electromagnetic immunity plays a critical role towards evaluating the EMC performance to avoid the high cost of redesign. This paper focuses on the Direct Power Injection (DPI) immunity of processor chips with different external double data rate3 (DDR3) synchronous dynamic random access memory (SDRAM) in consumer electronics. To complete the DPI test, a test board complying with the standard IEC62132-4 and a dedicated test code have been designed. The effect of DC power injection interference on same DDR model but different DDR pins and the same DDR pin but different DDR models were analysed, the results can be used to locate the system-level EMC issues and optimize the design.