Suppressing Effects of Ag Wetting Layer on Surface Conduction of Er Silicide/Si(001) Nanocontacts

Current-voltage electrical characteristics of Er silicide/Si（001） nanocontacts are measured in situ in a scanning tunneling microscopy system. Introduced as a new technique to suppress surface leakage conduction on Si（001）,a silver wetting layer is evaporated onto the substrate surface kept at room temperature with Er Si2 nanoislands already existing. The effects of the silver layer on the current-voltage characteristics of nanocontacts are discussed.Our experimental results reveal that the silver layer at coverage of 0.4–0.7 monolayer can suppress effectively the current contribution from the surface conduction path. After the surface leakage path of nanocontacts is obstructed, the ideality factor and the Schottky barrier height are determined using the thermionic emission theory, about 2 and 0.5 eV, respectively. The approach adopted here could shed light on the intrinsic transport properties of metal-semiconductor nanocontacts.

On the high conductive layer near the Moho and the transitional zone between the crust and mantle in Tianshui region

On the basis of MTS and DSS data in and near Tianshui region,the deep structure contour of the region was expounded.The regional distribution of the high conductive layer near the Moho in the region becomes one of the most obvious characters of the conductivity structure in the crust and mantle,and it is corresponding to the low S wave velocity zone near the Moho and is guessed as the transitional zone between the crust and mantle in the region.In this paper,the behaviour of medium and the thermodynamic circumstance of the conductive low shear velocity layer near the Moho were demonstrated emphatically,and the cause of formation of the layer was roughly explained under specified conditions of geographical environment and deep structure characters in this region.

Enhanced light extraction of GaN-based light-emitting diodes with periodic textured SiO_2 on Al-doped ZnO transparent conductive layer

We report an effective enhancement in light extraction of Ga N-based light-emitting diodes（LEDs） with an Al-doped Zn O（AZO） transparent conductive layer by incorporating a top regular textured SiO2 layer. The 2 inch transparent throughpore anodic aluminum oxide（AAO） membrane was fabricated and used as the etching mask. The periodic pore with a pitch of about 410 nm was successfully transferred to the surface of the SiO2 layer without any etching damages to the AZO layer and the electrodes. The light output power was enhanced by 19% at 20 m A and 56% at 100 m A compared to that of the planar LEDs without a patterned surface. This approach offers a technique to fabricate a low-cost and large-area regular pattern on the LED chip for achieving enhanced light extraction without an obvious increase of the forward voltage.

China Continental Conductive Layers and Its Relationship with Basin Evolution

? This paper plots out two deep distribution maps of the China continental crustal and upper mantle conductive layers, and discusses the origin of two kinds of conductive layers, based on the results of the magnetotelluric(MT) sounding research made by Chinese scientists in the last two decades. The MT prospecting shows that the conductive layers possibly exist in upper mantle and middle-lower crust in the Mesozoic and Cenozoic stretching basins, and they coincide with the uplifting of two kinds of conductive layers. These characteristics help to illustrate the deep dynamic settings that control the basin evolution.

The origin of the crustal conductive layer and the conductivity of supercritical brine（Ⅱ）

This paper is the second one of a series of three papers on fluid evolution of the crust upper mantle and the causes of earthquakes. Based on the first paper, two conductive mechanisms of the crustal conductive layer(CCL), graphite and supercritical saline aqueous fluids, are discussed. As there are difficulties for graphite model, the supercritical fluids are investigated in this paper concerning the phases, the electrically conductive behaviors, the evolution and the sealing mechanisms of the fluids. It is obvious that this model is reasonable to explain the geophysical and geochemical characteristics of the CCL presented in the first paper.

Thermal Conductance of Cu and Carbon Nanotube Interface Enhanced by a Graphene Layer

Thermal conduetances between Cu and graphene covered carbon nanotubes （gCNTs） are calculated by molecular dynamics simulations. The results show that the thermal conductance is about ten times larger than that of Cu- CNT interface. The enhanced thermal conductance is due to the larger contact area introduced by the graphene layer and the stronger thermal transfer ability of the Cu-gCNT interface. From the linear increasing thermal conductance with the increasing total contact area, an effective contact area of such an interface can be defined.

Transforming a Two-Dimensional Layered Insulator into a Semiconductor or a Highly Conductive Metal through Transition Metal Ion Intercalation

Atomically thin two-dimensional(2D) materials are the building bricks for next-generation electronics and optoelectronics, which demand plentiful functional properties in mechanics, transport, magnetism and photoresponse.For electronic devices, not only metals and high-performance semiconductors but also insulators and dielectric materials are highly desirable. Layered structures composed of 2D materials of different properties can be delicately designed as various useful heterojunction or homojunction devices, in which the designs on the same material(namely homojunction) are of special interest because preparation techniques can be greatly simplified and atomically seamless interfaces can be achieved. We demonstrate that the insulating pristine ZnPS_3, a ternary transition-metal phosphorus trichalcogenide, can be transformed into a highly conductive metal and an n-type semiconductor by intercalating Co and Cu atoms, respectively. The field-effect-transistor(FET) devices are prepared via an ultraviolet exposure lithography technique. The Co-ZnPS_3 device exhibits an electrical conductivity of 8 × 10^(4) S/m, which is comparable to the conductivity of graphene. The Cu-ZnPS_3 FET reveals a current ON/OFF ratio of 1-05 and a mobility of 3 × 10^(-2 )cm^(2)·V^(-1)·s^(-1). The realization of an insulator, a typical semiconductor and a metallic state in the same 2D material provides an opportunity to fabricate n-metal homojunctions and other in-plane electronic functional devices.

The crustal fluid evolution and the causes of earthquakes(Ⅲ)

This paper is the third one of a series of three papers on the fluid evolution of the crust upper mantle and the causes of earthquakes. Based on the last two papers, a model of the crustal resistivity structure and the deep seated fluid evolution is presented, and also a seismogeny theory is set up, which is called the potential kinetic energy transformation model. In this model, the crustal deep seated fluid evolution is considered to take the most important effect on the seismogenic process. Taking the Tangshan M 7.8 earthquake of 1976 as an example, the earthquakes occurred in a pull apart rifting basin are analyzed, and finally the crust outgassing in the seismogenic processes is discussed, referring to the here presented theory of seismogeny.

The earthquake distribution and the resistivity structure in the Chinese mainland（Ⅰ）

This paper is the first one of a series of three papers on the fluid evolution of the crust-upper mantle and the causes of earthquakes. Their relationship between the deep-seated fluids and the seismic activities are discussed from aspects of their macoscopic scale, microscopic mechanism and dynamic behaviors in the three papers respectively. Based on magnetotelluric sounding (MT) measurements conducted by Chinese geophysicists in more than 20 years, the maps of the upper mantle conductive layer (MCL) with a buried depth of>50 km and the crustal conductive layer (CCL) with a buried depth of >15 km in the Chinese mainland are Presented in this paper. The resistivity structure, the causes of conductive layers in crust-mantle and the relationships between earthquake distribution and conductive layers are discussed.

Aluminum matrix composites reinforced by molybdenum-coated carbon nanotubes

To extend the application of carbon nanotubes （CNTs） and explore novel aluminum matrix composites,CNTs were coated by molybdenum layers using metal organic chemical vapor deposition,and then Mo-coated CNT （Mo-CNT）/Al composites were prepared by the combination processes of powder mixing and spark plasma sintering.The influences of powder mixing and Mo-CNT content on the mechanical properties and electrical conductivity of the composites were investigated.The results show that magnetic stirring is better than mechanical milling for mixing the Mo-CNTs and Al powders.The electrical conductivity of the composites decreases with increasing Mo-CNT content.When the Mo-CNT content is 0.5wt%,the tensile strength and hardness of Mo-CNT/Al reach their maximum values.The tensile strength of 0.5wt% Mo-CNT/Al increases by 29.9%,while the electrical conductivity only decreases by 7.1%,relative to sintered pure Al.The phase analysis of Mo-CNT/Al composites reveals that there is no formation of Al carbide in the composites.

Impacts of reduced wind speed on physiology and ecosystem carbon flux of a semi-arid steppe ecosystem

Decreasing wind speed is one aspect of global climate change as well as global warming, and has become a new research orientation in recent decades. The decrease is especially evident in places with frequent perennially high wind speeds. We simulated decreased wind speed by using a steel-sheet wind shield in a temperate grassland in Inner Mongolia to examine the changes in physical environmental variables, as well as their impacts on the photosynthesis of grass leaves and net ecosystem exchange （NEE）. We then used models to calculate the variation of boundary layer conductance （BLC） and its impact on leaf photosynthesis, and this allowed us to separate the direct effects of wind speed reduction on leaf photo- synthesis （BLC） from the indirect ones （via soil moisture balance）. The results showed that reduced wind speed primarily resulted in higher moisture and temperature in soil, and indirectly affected net assimilation and water use efficiency of the prevalent bunch grass Stipa krylovii. Moreover, the wind-sheltered plant community had a stronger ability to sequester carbon than did the wind-exposed community during the growing season.

Crust-mantle structure feature and the seismic activity of the main tectonic units in the North Tanlu fault zone

Using recent data of geoscience transaction in Northeast China, the author analyses and studies the crust-upper mantle structure feature of the North Tanlu fault zone. The result shows the crust-mantle structure are obvious difference at both sides of the North Tanlu fault zone. The fault activity and segmentation are closely related with abruptly change zone of the crust-upper mantle structure. There is a clear mirror image relationship between the big geomorphic shape and asthenosphere undulate, the former restricts tectonic stability and tectonic style of dif- ferent crustal units. The significantly strengthening seismicity of north set and south set in the North Tanlu fault zone just correspond to the low-velocity and high conductivity layer of crust-upper mantle. In the North Tanlu fault zone, the main controlling structure of the mid-strong seismic generally consists of the active fault sectors, whose crust-mantle structure is more complicated in rigidity massif.

An Investigation of Deep Electrical Structure of Qiangtang Basin,Xizang(Tibet),China

In order to study the deep geoelectrical structure and the regional geological structure and detect potential oil and gas areas in Qiangtang basin in northern Xizang (Tibet ), 222 MT soundings were conducted along three N - S MT profiles across the basin .The MT results indicate that the south and north parts of the Qiangtang basin have a good contrast in the deep electri cal structure . In the south Qiangtang , there are generally two high conductivity layers in the crust . The first is at a depth of about 10 - 25 km and possesses a resistivity of about 10 - 80 Ωm .The second ,the high conductivity layer in the lower crust ,is at a depth of about 40 - 70 km with 3 - 50 Ωm .In the north Qiangtang .there is generally one high conductivity layer .It is at a depth of about 10 - 30 km and the resistivity is about 1-60 Ωm . The thickness of the second high conductivity layer in both the south Qiangtang and the Bangong-Nujiang suture is much greater than that of the first .The thickness of the lithosphere is about 110-120 km for the Bangong-Nujiang suture ,115 km for the south Qiangtang and 100-130 km for the north Qiangtang . On the difference of the deep electrical structures of the crust between the south and the north Qiangtang , we believe that it is related to the eastward flow of the crustal substance .

Studies of electrical properties of rocks under high temperature and pressure

Studies of the rocks′ electrical properties under high temperature and pressure have found favors in the geophysicist′s eyes, because those studies are becoming to be the important methods to understand the earth′s interior materials, their migration and evolution. This article introduces the development and significant of those studies from the measurements, instruments and affections, etc .

Elastomeric polymers for conductive layers of flexible sensors: Materials, fabrication, performance, and applications

In the wave of the Internet era created by computer and communication technology,flexible sensors play an important role in accurately collecting information owing to their excellent flexibility,ductility,freeform bending or folding,and versatile structural shapes.By endowing elastomeric polymers with conductivity,researchers have recently devoted extensive efforts toward developing high-performance flexible sensors based on elastomeric conductive layers and exploring their potential applications in diverse fields ranging from project manufacturing to daily life.This review reports the recent advancements in elastomeric polymers used to make conductive layers,as well as the relationships between elastomeric polymers and the performance and application of flexible sensors are comprehensively summarized.First,the principles and methods for using elastomeric polymers to construct conductive layers are provided.Then,the fundamental design,unique properties,and underlying mechanisms in different flexible sensors(pressure/strain,temperature,humidity)and their related applications are revealed.Finally,this review concludes with a perspective on the challenges and future directions of high-performance flexible sensors.