Improved interface properties of an HfO_2 gate dielectric GaAs MOS device by using SiN_x as an interfacial passivation layer

A GaAs metal-oxide-semiconductor （MOS） capacitor with HfO2 as gate dielectric and silicon nitride （SiNx） as the interlayer （IL） is fabricated. Experimental results show that the sample with the SiNx IL has an improved capacitance- voltage characteristic, lower leakage current density （0.785 × 10^-6 Alcm^2 at Vfo ＋ 1 V） and lower interface-state density （2.9 × 10^12 eV^-1 ·cm^-2） compared with other samples with N2- or NH3-plasma pretreatment. The influences of post- deposition annealing temperature on electrical properties are also investigated for the samples with SiNx IL. The sample annealed at 600 ℃ exhibits better electrical properties than that annealed at 500 ℃, which is attributed to the suppression of native oxides, as confirmed by XPS analyses.

FABRICATION OF STRAINED-Si CHANNEL P-MOSFET's ON ULTRA-THIN SiGe VIRTUAL SUBSTRATES

In the ultra-thin relaxed SiGe virtual substrates, a strained-Si channel p-type Metal Oxide Semiconductor Field Effect Transistor (p-MOSFET) is presented. Built on strained-Si/240nm relaxed-Si0.8 Ge0.2/ 100nm Low Temperature Si (LT-Si)/10nm Si buffer was grown by Molecular Beam Epitaxy (MBE), in which LT-Si layer is used to release stress of the SiGe layer and made it relaxed. Measurement indicates that the strained-Si p-MOSFET's (L=4.2μm) transconductance and the hole mobility are enhanced 30% and 50% respectively, compared with that of conventional bulk-Si. The maximum hole mobility for strained-Si device is 140cm2/Vs. The device performance is comparable to devices achieved on several μm thick composition graded buffers and relaxed-SiGe layer virtual substrates.

Gut Bacterial and Lactobacilli Communities of Weaning Piglets in Response to Mannan Oligosaccharide and Sugar Beet Pulp In vitro Fermentation

Microbiota in the gastrointestinal tract （GIT） of piglets during weaning transition can experience a sharp change which could result in growth reduction and diarrhea of weaned piglets. Dietary manipulations can play an important role in attenuating such changes caused by weaning stress. Therefore, ileal and colonic contents of weaned piglets were used as inocula, mannan oligosaccharide （MOS） or sugar beet pulp （SBP） was supplied as single energy sources to investigate effects of MOS or SBP on the shifts of gastro-intestinal microflora and lactobacilli populations. The universal bacteria- and lactobacilli-specific PCR/denaturing gradient gel electrophoresis （DGGE）, cloning and sequencing techniques were used. DGGE profiles of the universal bacteria showed that great changes were found in the position, numbers and intensity of dominant bands after fermentation. The similarity of bacterial community between ileum and colon was increased to 85-97% by MOS or SBP treatment after fermentation from the similarity with 20% before fermentation. MOS treatment significantly increased the bacterial diversity and band number in both ileal and colonic fermentation （P〈0.05）. SBP treatment significantly increased the bacterial diversity and band number in colon （P〈0.05）. It implies that some species were enriched by the addition of MOS or SBP to increase the similarity and diversity of bacterial community in weaned piglets. Five specific bands appearing in MOS or SBP treatment group after fermentation were cloned and sequenced, the changes of species related to Prevotella and Ruminococcus were observed. Two bands related to uncultured bacterium with 98% similarity were detected by MOS or SBP treatment. However, there were no effects on the similarity, diversity index and lactobacilli species revealed by MOS or SBP treatment. These results imply that MOS or SBP could have beneficial effects on the weaning piglets by stablizing microbiota in the GIT microflora.

Quality of experience based scheduling algorithm in LTE network with various traffics

Quality of experience （ QoE ） based scheduling algorithm of long term evalution （ LTE ） network with various traffics is studied. Utility functions are adopted to estimate mean opinion score （MOS） for different traffics and a new MOS metric called normalized MOS is defined. A scheduling algorithm based on normalized MOS and greedy algorithm is proposed, aiming at maximizing the entirety MOS level of the whole users in the cell. We compare the performance of the proposed algorithm with other typical scheduling algorithms and the simulation results show that the algorithm pro- posed outperform other ones in term of QoE and fairness.

Aether原理图驱动版图工具Device Matching功能的原理与实现

本文针对Aether原理图驱动版图工具中的器件匹配功能的原理与机制予以论述。本文首先探讨当前深亚微米工艺下进行器件失配的由来;其次描述了器件匹配的原理;最后针对设计工艺中不同的器件类型晶体管(MOS)、电阻(Resistor)等进行匹配实现,并基于Aether原理图驱动版图工具给出该功能实现的实际效果图,提出了产品化过程中注意到一些问题。市场实践表明,该功能在版图设计过程中能够帮助版图工程师快速完成匹配器件的版图生成,从而极大提高了版图工程师的设计效率。

Electrical characteristics of MOS capacitor using amorphous Gd_2O_3-doped HfO_2 insulator

This work described the electrical characteristics of a kind of amorphous Gd2O3-doped HfO2 insulator for high-k metal-oxide-semiconductor(MOS) capacitors.Compared with pure HfO2,the doped HfO2 with an optimum concentration of Gd2O3 as MOS gate dielectric exhibited a lower leakage current,thinner effective oxide thickness and less fixed oxide charges density.The result indicated that Gd2O3 doping power of 60 W exhibited the best electrical characteristics,maximum capacitance,lowest leakage current of 9.35079...

Defect-rich MoS2 nanowall catalyst for efficient hydrogen evolution reaction

Designing efficient electrocatalysts for the hydrogen evolution reaction （HER） has attracted substantial attention owing to the urgent demand for clean energy to face the energy crisis and subsequent environmental issues in the near future. Among the large variety of HER catalysts, molybdenum disulfide （MoS2） has been regarded as the most famous catalyst owing to its abundance, low price, high efficiency, and definite catalytic mechanism. In this study, defect-engineered MoS2 nanowall （NW） catalysts with controllable thickness were fabricated and exhibited a significantly enhanced HER performance. Benefiting from the highly exposed active edge sites and the rough surface accompanied by the robust NW structure, the defect-rich MoS2 NW catalyst with an optimized thickness showed an ultralow onset overpotential of 85 mV, a high current density of 310.6 mA·cm^-2 at η = 300 mV, and a low potential of 95 mV to drive a 10 mA·cm^-2 cathodic current. Additionally, excellent electrochemical stability was realized, making this freestanding NW catalyst a promising candidate for practical water splitting and hydrogen production.

Folded MoS2 layers with reduced interlayer coupling

We study molybdenum disulfide （MoS2） structures generated by folding single-layer and bilayer MoS2 flakes. We find that this modified layer stacking leads to a decrease in the interlayer coupling and an enhancement of the photoluminescence emission yield. We additionally find that folded single-layer MoS2 structures show a contribution to photoluminescence spectra of both neutral and charged excitons, which is a characteristic feature of single-layer MoS2 that has not been observed in multilayer MoS2. The results presented here open the door to fabrication of multilayered MoS2 samples with high optical absorption while maintaining the advantageous enhanced photoluminescence emission of single-layer MoS2 by controllably twisting the MoS2 layers.

An efficient method for comprehensive modeling and parasitic extraction of cylindrical through-silicon vias in 3D ICs

To build an accurate electric model for through-silicon vias （TSVs） in 3D integrated circuits （ICs）, a resistance and capacitance （RC） circuit model and related efficient extraction technique are proposed. The circuit model takes both semiconductor and electrostatic effects into account, and is valid for low and medium signal frequencies. The electrostatic capacitances are extracted with a floating random walk based algorithm, and are then combined with the voltage-dependent semiconductor capacitances to form the equivalent circuit. Compared with the method used in Synopsys＇s Sdevice, which completely simulates the electro/semiconductor effects, the proposed method is more efficient and is able to handle the general TSV layout as well. For several TSV structures, the experimental results validate the accuracy of the proposed method for the frequency range from l0 kHz to 1 GHz. The proposed method demonstrated 47× speedup over the Sdevice for the largest 9-TSV case.

Silicon nanowire ratioed inverters on bendable substrates

In this study, we demonstrate the performance of silicon nanowire （SiNW） n-metal oxide semiconductor （MOS） and p-MOS ratioed inverters that are fabricated on bendable substrates. The electrical characteristics of the fabricated devices can be controlled by adjusting the load voltage. The logic swings of the n- and p-MOS ratioed inverters at a low supply voltage of 1V are 80% and 96%, respectively. The output voltage level of the p-MOS ratioed inverter is close to rail-to-rail operation. The device also exhibits stable characteristics with good fatigue properties. Our bendable SiNW ratioed inverters show promise as a candidate building block for future bendable electronics.

Optoelectronic devices based on two-dimensional transition metal dichalcogenides

In the past few years, two-dimensional （2D） transition metal dichalcogenide （TMDC） materials have attracted increasing attention of the research community, owing to their unique electronic and optical properties, ranging from the valley-spin coupling to the indirect-to-direct bandgap transition when scaling the materials from multi-layer to monolayer. These properties are appealing for the development of novel electronic and optoelectronic devices with important applications in the broad fields of communication, computation, and healthcare. One of the key features of the TMDC family is the indirect-to-direct bandgap transition that occurs when the material thickness decreases from multilayer to monolayer, which is favorable for many photonic applications. TMDCs have also demonstrated unprecedented flexibility and versatility for constructing a wide range of heterostructures with atomic-level control over their layer thickness that is also free of lattice mismatch issues. As a result, layered TMDCs in combination with other 2D materials have the potential for realizing novel high-performance optoelectronic devices over a broad operating spectral range. In this article, we review the recent progress in the synthesis of 2D TMDCs and optoelectronic devices research. We also discuss the challenges facing the scalable applications of the family of 2D materials and provide our perspective on the opportunities offered by these materials for future generations of nanophotonics technology.