The fabrication of nickel silicide ohmic contacts to n-type 6H-silicon carbide

This paper reports that the nickel silicide ohmic contacts to n-type 6H-SiC have been fabricated. Transfer length method test patterns with NiSi/SiC and NiSi2/SiC structure axe formed on N-wells created by N^＋ ion implantation into Si-faced p-type 6H-SiC epilayer respectively. NiSi and NiSi2 films are prepared by annealing the Ni and Si films separately deposited. A two-step annealing technology is performed for decreasing of oxidation problems occurred during high temperature processes. The specific contact resistance Pc of NiSi contact to n-type 6H-SiC as low as 1.78× 10^-6Ωcm^2 is achieved after a two-step annealing at 350 ℃for 20 min and 950℃ for 3 min in N2. And 3.84×10-6Ωcm^2 for NiSi2 contact is achieved. The result for sheet resistance Rsh of the N＋ implanted layers is about 1210Ω/□. X-ray diffraction analysis shows the formation of nickel silicide phases at the metal/n-SiC interface after thermal annealing. The surfaces of the nickel silicide after thermal annealing are analysed by scanning electron microscope.

Design and Fabrication of MEMS Gyroscopes on the Silicon-on-insulator Substrate with Decoupled Oscillation Modes

The mode coupling is a major factor to affect the precision of the micro electromechanical systems（MEMS） gyroscope. Currently, many MEMS gyroscopes with separate oscillation modes for drive and detection have been developed to decrease the mode coupling, but the gyroscope accuracy can not satisfy the high-precision demand well. Therefore, high performance decoupled MEMS gyroscopes is still a hot topic at present. An innovative design scheme for a MEMS gyroscope is designed, and in this design, the inertial mass is divided into three parts including the inner mass, the outer mass and the main frame mass. The masses are supported and separated by a set of mutually orthogonal beams to decouple their movements. Moreover, the design is modelled by multi-port-element network（MuPEN） method and the simulation results show that the mode coupling of the gyroscope between driving and sensing mode was eliminated effectively. Furthermore, we proposed a new silicon-on-insulator（SOI） process to fabricate the gyroscope. The scale factor of the fabricated gyroscope is 8.9 mV/（（~）os） and the quality factor（Q-factor） is as high as 600 at atmosphere pressure, and then, the resonant frequency, scale factor and bias drift has been test. Process and test results show that the proposed MEMS gyroscope are effective for decrease mode coupling, furthermore, it can achieve a high performance at atmosphere pressure. Furthermore, the MEMS gyroscope can achieve a high performance at atmosphere pressure. The research can be taken as good advice for the design and fabrication of MEMS gyroscope, meanwhile, it also provides technical support for speeding up of MEMS gyroscope industrialization.

Demonstration of a 4H SiC Betavoltaic Nuclear Battery Based on Scbottky Barrier Diode

A 4H SiC betavoltaic nuclear battery is demonstrated. A Schottky barrier diode is utilized for carrier separation. Under illumination of Ni-63 source with an apparent activity of 4mCi/cm^2, an open circuit voltage of 0.49 V and a short circuit current density of 29.44nA/cm^2 are measured. A power conversion efficiency of 1.2% is obtained. The performance of the device is limited by low shunt resistance, backscattering and attenuation of electron energy in air and Schottky electrode. It is expected to be significantly improved by optimizing the design and processing technology of the device.

Formation of the intermediate semiconductor layer for the Ohmic contact to silicon carbide using Germanium implantation

By formation of an intermediate semiconductor layer （ISL） with a narrow band gap at the metallic contact/SiC interface, this paper realises a new method to fabricate the low-resistance Ohmic contacts for SiC. An array of transfer length method （TLM） test patterns is formed on N-wells created by P＋ ion implantation into Si-faced p-type 4H- SiC epilayer. The ISL of nickel-metal Ohmic contacts to n-type 4H-SiC could be formed by using Germanium ion implantation into SiC. The specific contact resistance pc as low as 4.23×10-5Ω·cm2 is achieved after annealing in N2 at 800 ℃ for 3 min, which is much lower than that （〉 900℃） in the typical SiC metallisation process. The sheet resistance Rsh of the implanted layers is 1.5 kΩ/□. The technique for converting photoresist into nanocrystalline graphite is used to protect the SiC surface in the annealing after Ge＋ ion implantations.

A betavoltaic microbattery based on PIN diodes

A betavohaic Microbattery was studied. The diode was composed of a PIN structure with an active area of 10 mm × 10 mm to collect the charge from a 10mCi Ni-63 source. An open circuit voltage of 0. 16 V and a short circuit current density of 67.6 nA/cm2 were measured. An efficiency （η） of 1.44% was obtained. The performance of device was limited by high series resistance, edge recombination and attenuation of electron in PIN diodes. It is expected to be improved by optimizing the design and using more suitable radioisotope.

Assessment of the Wind Field in the East Coast Algerian Regions for the Installation of Wind Farms

The available electricity generated by a wind power generation system depends on mean wind speed, standard deviation of wind speed and the location of installation. Since year-to-year variation on annual mean wind speed is hard to predict, wind speed variations during a year can be well characterized in terms of a probability distribution function, as well Weibull distribution has been one of the most commonly used, accepted and recommended distribution to determine wind energy potential. In this study, the two Weibull parameters of the wind speed distribution function （the shape parameter k （dimensionless） and the scale parameter c （m/s））, were computed from the wind speed data for Algerian east coastal regions, recording over a 1 l-year period （1995-2005）. It was found that the numerical values of both Weibull parameters （k and c） vary over a wide range. The yearly values ofk range from 1.20 to 1.94, while those of c are in the range from 4.31 to 1.94. To minimize the uncertainties of statistical calculation, a spatial representation indicating distribution and occurrence frequency the direction from which the wind comes, appears a very primordial step. Over the whole valid data during the study period, the compass shows that there is no dominant direction marked. However, we can identify a preferred wind direction. The statistical results correspond to the analysis of the rose compass.

A new micro programmable blazed grating (μPBG) and its application to multispectral imaging

一个新微可编程的燃烧栅栏(PBG ) 被设计，制作并且描绘了使用二层的多晶硅表面 micromachining 过程。介绍的 PBG 在结构简单并且有为一个宽波长范围的连续光谱的调节的能力。最大化运作的燃烧角度，当为栅栏条板的关键部件，和它的高度接近了空气差距，酒窝结构被采用。由大小，发达 PBG 样品能到达 5.19 的一个最大的燃烧角度 ???????? 瘠瑡牥瑩吗？

Experimental and Numerical Analyses of the Pull-out Response of a Steel Post/Bovine Bone Cementless Fixation

Effect of initial interference fit on pull-out strength in cementless fixation between bovine tibia and smooth stainless steel post was investigated in this study. Compressive behavior of bovine spongious bone was studied using mechanical testing in order to evaluate the elastic-plastic properties in different regions of the proximal tibia. Friction tests were carried out in the aim to evaluate the friction behavior of the contact between bovine spongious bone and stainless steel. A cylindrical stainless steel post inserted in a pre-drilled bovine tibia with an initial interference fit was taken as an in vitro model to assess the contribution of post fixation to the initial stability of the Total Knee Arthroplasty （TKA） tibial component. Pull-out experiments were carried out for different initial interference fits. Finite Element Models （FEM） using local elastic-plastic properties of the bovine bone were developed for the analysis of the experimental ultimate pull-out force results. At the post/bone interface, Coulomb friction was considered in the FEM calculations with pressure-dependent friction coefficient. It was found that the FEM results of the ultimate force are in good agreement with the experimental results. The analysis of the FEM interfacial stresses indicates that the micro-slip initiation depends on the local bone properties.