A unique metallization scheme has been developed for obtaining both Schottky and low-resistance Ohmic contacts to n-GaN. It has been demonstrated that the same metallization can be used to make both Schottky and Ohmic contacts to n-GaN using a Ni/Au bilayer composite with Ni in contact to GaN. Using this metallization, contacts with a specific contact resistivity, ρs, as low as 6.9×10−6 Ω cm2 for a doping level of 5.0×1017 cm−3 was obtained after annealing the sample for 10 s at 800 °C in a rapid thermal annealer. The presence of only (111)Au and (111)Ni peaks in the x-ray diffraction (XRD) pattern of as-deposited samples indicates that both metals participate to form epitaxial or highly textured layers on the basal GaN plane. When the contact layer is annealed, Au and Ni react with GaN creating interfacial phases. Both XRD and transmission electron microscopy confirm that Ni3Ga and Ni2Ga3 intermetallic phases together with Au and Ni based face-centered-cubic solid solutions, are formed during annealing. The high optical transmission achieved (in the range of 400–700 nm) through this contact after annealing suggests that it is, indeed, very useful for electro-optic device applications. The contacts also demonstrate exceptional thermal stability. Experimental data suggest that the formation of interfacial phases with a low work function is responsible for the low contact resistance of the system. The Ni–Au layer forms a robust composite enabling the contacts to have high-temperature applications. Unlike the Ni/Au Ohmic contact, the Ni/Au Schottky contact to n-GaN has a relatively large barrier height. Improved material quality and Schottky contact technology are needed to improve upon the reverse breakdown voltage.

We generated complete mitochondrial genome sequences data for 4 genera (Onchidium, Platevindex, Paraoncidium and Peronia) in Onchidiidae to construct a phylogenetic tree in conjunction with other 9 existing data among gastropods. The topology showed that the taxa clustered into two main groups of four species, one of which included Onchidium struma and the Platevindex mortoni, the other Paraoncidium reevesii and Peronia verruculata. The process in Pulmonata from sea to land in accordance with the evolution of respiratory organs from branchial gills to pulmonary cavity has been shown. This will also constitute a framework for phylogeny evolution analysis, systematic classfication of Onchidiidae and other euthyneurans (pulmonates and opisthobranchs).

Wind speed forecasting is critical for wind energy conversion systems. Adaptive and reliable methods and techniques of wind speed forecasting are urgently needed in view of the stochastic nature of wind resource, which is varying from time to time and from site to site. Multi-step-ahead speed forecasting is built with empirical mode decomposition (EMD) method and RBF neural network, which makes use of non-linear and non-stationary signal characteristics. Time series of original wind speed data is decomposed by EMD method. And RBF neural network is used to predict the decomposition of the various components. Experimental results show that the method effectively improves the accuracy and the reliability of wind speed forecasting.

Describes the historical background of modular construction technology, focusing on the development of power from a modular, development history, comparative advantages and disadvantages of other aspects of the study was to investigate, and thus the modularization of the prospect.

The boiler-turbine coordinated system is a very important process of a power generation unit. This paper takes 300MW power plant as the controlled object and conducts simulation study on its different kinds of load control modes under the environment of the MATLAB. The parameters of PID controller are optimized using signal constraint (S-C) module in Simulink toolbox. By analyzing the results of the simulation and comparing both the advantages and disadvantages of them, we can provide references for the choices of load control mode of power unit.