Solar energy hydrogen production is one of the best solutions for energy crisis. Therefore, finding effective photocatalytic materials that are able to split water under the sunlight is a hot topic in the present research fields. In addition, theoretical prediction is a present low-cost important method to search a new kind of materials. Herein, with the aim of seeking efficient photocatalytic material we investigated the photocatalytic activity of GaAs monolayer by the first principles calculation. According to the obtained electronic and optical properties, we primarily predicted the photocatalytic water splitting activity of GaAs monolayer, which the result further confirmed by the calculated reaction free energy. More remarkably, predicted carrier mobility of GaAs monolayer 2838 cm2V−1s−1 is higher than 200 cm2V−1s−1 of MoS2. Our finding provides a promising material for the development of renewable energy conversion and a new outlook for better designing of a superior photocatalyst for water splitting.

The relic abundance of asymmetric Dark Matter particles in the scalar-tensor model is analyzed in this article. We extend the numeric and analytic calculation of the relic density of the asymmetric Dark Matter in the standard cosmological scenario to the nonstandard cosmological scenario. We focus on the scalar-tensor model. Hubble expansion rate is changed in the nonstandard cosmological scenario. This leaves its imprint on the relic density of Dark Matter particles. In this article we investigate to what extent the asymmetric Dark Matter particle's relic density is changed in the scalar-tensor model.We use the observed present day Dark Matter abundance to find the constraints on the parameter space in this model. *

A direct high-k/Si gate stack has been proposed for gate oxide scaling. With LaCe-silicate, an EOT of 0.64 nm with an average dielectric constant (k av ) of 17.4 has been obtained and an extremely low gate leakage current (J g ) of 0.65 A/cm 2 . The flatband voltage (V fb ) can be controlled by the compositional ratio of La in the LaCe-silicate layer. Furthermore, incorporation of Ge atom into the silicate layer can effectively shift the V fb to positive direction. IntroductionThe scaling in gate dielectric below equivalent oxide thickness (EOT) of 0.7 nm essentially requires a technique to directly contact high-k dielectrics to Si substrate with good interfacial property [1]. Several techniques, including cycle deposition and annealing, or oxygen scavenging process, have been so far reported to achieve a direct contact of high-k/Si structure [2,3]. The high-k/Si interface with HfO 2 is sensitive to the oxygen partial pressure during the process, so that one must choose a process within a window to achieve a direct high-k/Si structure (Fig.1). On the other hand, La 2 O 3 can achieve a direct high-k/Si interface by forming a silicate layer with fairly nice interface properties [4]. However, the excess formation of silicate results in the increase in EOT. CeO 2 has an advantage in the wide process window to achieve a direct high-k/Si interface. In terms of gate leakage current (J g ), silicates have advantage in widening the band gap at the cost of EOT (Fig.2). Therefore, this work focuses on the combination of a Si-rich Ce-silicate with La 2 O 3 to achieve a direct high-k/Si interface with both reduction in J g and EOT.

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In this work, thin film transistors (TFTs) based on the ZnO-doped with different concentrations of Li were fabricated by radio frequency sputtering. Using the optimal Li doping concentration of 1% and rationally designed passivation layer (PVL), a TFT with high mobility of 28.5 cm2/Vs, low SS of 0.28 V decade−1, high Ion/Ioff of 107 and small Vth of 0.8 V were obtained. Moreover, the 1% Li-doped ZnO TFT with Al2O3 PVL exhibits the best stability with the small Vth shifts of 1.1 (− 1.2) V and 1.6 (− 1.8) V under gate bias and light illumination test. Low-frequency noise and x-ray photo-electron spectroscopy band structure analysis suggests that the enhanced properties and stability are mostly due to the Li doping concentration. Because the Li doping not only increased the carrier concentration, but also reduced the oxygen vacancy defects and interface trap density. In addition, the high quality Al2O3 PVL reduced the photo-adsorption/desorption behavior, and protected the channel from environmental influences. Overall, the reliable and high performance Li-doped ZnO TFTs have a great potential in flat-panel display application.

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