Yao Lv

Recent progress of ohmic contact on ZnO

ZnO as an excellent candidate for UV light emitters, varistors, transparent high-power electronics, surface acoustic wave devices, piezoelectric transducers, and chemical and gas sensors could be integrated in a SiP (system-in-package). The SiP could be a critical part in sensor nodes in a sensor network. Normally, the ZnO device in SiP is fabricated with nanoscale films which can be compatible with other materials and processing in a package. However, despite the great potential for electron and photonic applications, ZnO device fabrication is difficult to obtain good ohmic contact. The low resistance and thermal stable ohmic contacts is critical to realize high-performance ZnO-based devices. In this paper, the recent advances of ohmic contacts on ZnO are analyzed and reviewed. The mechanism of the energy band bending at the interface of the semiconductor and the metal is discussed. The factors of forming good quality ZnO films such as the choice of the substrate and the method to deposit ZnO film, the effect of the contact resistance and thermal stability of ohmic contacts are summarized.

A study of high-density embedded capacitor for silicon-substrate package

Rapidly growing performance and mixed-signal integration is driving the need for product component miniaturization in electronics applications. Embedded passive technology is a potentially attractive solution to replace discrete passives. Embedded capacitors are widely used for broad range of applications including filtering, tuning and power-bus decoupling in the substrate. Micro-Electron-Mechanical System (MEMS) process based on silicon and deep etching 3D patterns on silicon substrate is used. The fabrication process and properties of a semiconductor decoupling capacitor with high capacitance density is reported in this paper. Measurement results indicate that the capacitance density can reach 12nF/mm2, which is 10–12 times that planar semiconductor capacitors, and that the decoupling frequency range is between from 10MHz to 3.2GHz.

Low-cost high-efficiency 4 channel pluggable parallel optical transceiver using optoelectronic MCM packaging technologies

A compact 4times2-channel parallel optical MCM transceiver with data rates up to 3.125 Gb/s per channel was studied for very short reach (VSR) interconnection. The transceiver was based on 1times4 VCSEL and PD arrays of 850 nm wavelength, and a 12-fiber-ribbon as the transmission medium. Greatly relaxed alignment tolerance and high coupling efficiency between optoelectronic (OE) device arrays and fiber arrays were achieved. The eye-diagram at 2.5 Gb/s was measured under 231-1 pseudorandom bit stream (PRBS).

Effect of Marangoni Convection on Welding Pool of Plasma Direct Metal Forming Finite Element Model

With considering the Marangoni convection in the molten pool on plasma direct metal forming process, a finite element model posed to describe and reflect the flow in the molten pool. Results of temperature distribution modeling prepared by plasma direct metal forming process of metal powders in an Ar environment were numerically obtained and compared with experimental data. Powders of Fe314 and base plates of R235 steel were taken as sample materials. In the experiment a multi-stream nozzle capable of delivering metal powder coaxially with the plasma arc was used. The model revealed that the velosity of the front part of the pool is a little slower than aft part. Marangoni convection reinforced the convection and enhanced the heat transfer. Profile of the model is the same as the experimental data. This allows us to conclude that the model can be applied for preselecting the process parameters. Keywords: plasma, rapid forming, temperature field, Marangoni convection.

Synthesis and Properties of Poly-Acrylate Emulsion Modified by Organ Silicone

An acrylate emulsion was modified by vinyltriethoxy silane (VTES, trade name A-151) to synthesize the acrylosilane emulsion with high properties. The effect of the amount of A-151 on the properties pf the emulsion was investigated. It found that adding 6 % of A-151, the fraction extensibility of the emulsion film could be increased to 530 % and its water absorption was reduced to 4.2 % while adding 10 % of A-151. On the other side, the particle size and distribution of the emulsion were analyzed by Scanning Electron Microscopy (SEM) and Malvern Particle Size Analyzer (PSA) respectively. The measuring results showed that the particle diameter of the modified emulsion could be between 100 and 700 nanometers, and the properties of the emulsion could be apparently improved by adding A-151 into the system of emulsion polymerization.

Research on Rust-Based Anticorrosion Coating

The continuous development in the field of protective coatings and the search for newer rust-based anticorrosion with improved properties have led to the emergence of rust-based anticorrosion for high performance organic coatings for corrosion protection. In this study, one such rust-based anticorrosion coating have been formulated and coated over tinplate surfaces. The physical and anticorrosive properties of the coating were evaluated by accelerated laboratory tests (chemic immersion tests). The results are reported and conclusions are drawn in this paper.

On Implementation of Software Acoustic Cancellation

The implementation of a software acoustic echo canceller (AEC) on personal computers (PC) is much more difficult than just migration of the well defined algorithms. Software AECs have to deal with the diverse hardware environments, which are usually low-cost and inaccurate, and the software environment, which generally is committed to sharing resources through multi-tasking yet providing no real-time guarantees. Hardware differences lead to sampling rate differences and echo path nonlinearity, while the software environment can cause discontinuity of the audio stream. In this paper, these factors are investigated, and addressed by improved software AEC based on the coloration effect filter algorithm.

Microstructure and Properties of Ni-Base Coatings Obtained by Micro-Plasma Arc Cladding Processes

Microstructure and properties of Ni-base coatings obtained by micro-plasma arc cladding was investigated. A uniform clad coating was obtained after optimizing the cladding parameters by using NiCrBSi powder. Microstructure of the coatings observed by optical and scanning electron microscopy (SEM) indicated a homogenized microstructure. It has no evident heat-affected zone and no porosity. The phase of the coating was formed by γ-N solid solution, nickel boride Ni3B, carbide Cr21.34Fe1.66C6 and Cr2B3 type chromium boride. Although it likes the laser cladding coatings, micro-plasma coatings has its own characteristic. In addition, the average microhardness and nanohardness of coatings which were much higher than the substrate were observed, and the distribution of the microhardness was drawn.

A study on the characterization of quasi-three-dimensional PN junction capacitor

This paper discusses a novel quasi-three-dimensional PN Junction capacitor, which has a high density of capacitance (200nF/cm2) with a relatively high working frequency (3GHz). These properties are because of its unique trench structure. To identify the performance of this kind of capacitor, some tests were carried out at both low frequency and high frequency. Moreover, a typical power supply filter network was designed to compare the embedded capacitor with a commercial 2nF SMD 0402 capacitor.