First-principle study on optical properties of N-La-codoped anatase TiO

The electronic structures, deformation charge density, dipole moment, and optical properties of N-La-codoped anatase titanium dioxide (TiO2) are studied using the plane-wave ultrasoft pseudopotential method based on the density functional theory (DFT). The optical properties of two-ion-doped TiO2 are analyzed via electronic structures, deformation charge density, and dipole moment. For the model of N-La-doped TiO2 , a smaller atom fraction of N and La atoms induces better optical properties. The absorption edges of two doped TiO2 models redshift to the visible-light region.     

近紫外激发白光LED用Eu~(3+)、Sm~(3+)掺杂Y_2MoO_6荧光粉的合成及发光性质

本文采用溶胶-凝胶法分别制备了Eu~(3+)和Sm~(3+)掺杂Y_2MoO_6荧光粉。产物的结构、形貌和发光性质分别通过X射线衍射(XRD)、扫描电子显微镜(SEM)、发射光谱(PL)、激发光谱(PLE)及荧光寿命谱(Lifetime)等进行了表征。XRD证实产物为纯相单斜结构,空间群C2/c,SEM照片显示两种体系尺寸均在亚微米量级。激发光谱显示两种体系均能有效吸收近紫外波段光,并表现出良好的红色、橙红色发光性能。同时,深入研究了其发光机理、浓度淬灭效应及色度坐标。该系列荧光粉将在近紫外激发白光LED中有着潜在的应用价值。     

966nm半导体激光激发下ErYb：ZBLAN玻璃的上转换特征饱和现象

本文研究了单掺Er和ErYb共掺的ZBLAN玻璃的上转换发光现象,发现了一种新颖的“Er(0.3)Yb(0.5):ZBLAN样品上转换发光强度随激光功率变化的双对数曲线的斜率相对于Er(0.3):ZBLAN样品有明显的降低、但都保持着很好的直线”的这种“特征、饱和现象,它的上转换机制是一种新颖的“扩散－传递”机制：即Yb^3 -Yb^3 间能量扩散和随后的Yb^3 -Er^3 间能量传递。其“特征”饱和现象就是由“Yb^3 -Yb^3 ”间能量扩散导致的。     

Sm：CaS的电子俘获机制

用紫外光辐射单掺钐的ＣａＳ后，观察到很强的红外激励上转换发光。这是由不同格位的钐离子间的电荷转移引起的。本文研究了它的光学性质及有关的电子俘获机制。     

A two-dimensional analytical model for channel potential and threshold voltage of short channel dual material gate lightly doped drain MOSFET

An analytical model for the channel potential and the threshold voltage of the short channel dual-material-gate lightly doped drain （DMG-LDD） metal-oxide-semiconductor field-effect transistor （MOSFET） is presented using the parabolic approximation method. The proposed model takes into account the effects of the LDD region length, the LDD region doping, the lengths of the gate materials and their respective work functions, along with all the major geometrical parameters of the MOSFET. The impact of the LDD region length, the LDD region doping, and the channel length on the channel potential is studied in detail. Furthermore, the threshold voltage of the device is calculated using the minimum middle channel potential, and the result obtained is compared with the DMG MOSFET threshold voltage to show the improvement in the threshold voltage roll-off. It is shown that the DMG-LDD MOSFET structure alleviates the problem of short channel effects （SCEs） and the drain induced barrier lowering （DIBL） more efficiently. The proposed model is verified by comparing the theoretical results with the simulated data obtained by using the commercially available ATLASTM 2D device simulator.     

Magnetic Properties of Co-Doped TiO2 Films Grown on TiN Buffered Silicon Substrates

Co-doped TiO2 thin films are grown on TiN buffered silicon substrates by the pulsed laser deposition method and then hydrogenated. Transmission electron microscopy and high-angle annular dark-field scanning transmission electron microscopy measurements have shown that the TiN buffer layer can suffer a 400℃ deposition temperature and prevent the growth of silicon dioxide on silicon. After that, the room temperature ferromagnetism behaviors are observed in the hydrogenated samples, which are measured by the alternating gradient magnetometer. X- ray photoelectron spectroscopy and x-ray absorption fine structure measurements have revealed the existence of cobalt clusters. According to the material analysis, the magnetic behavior after hydrogenation is suggested to be induced by the enhancement of cobalt dusters.     

Spin Polarization Properties of Na Doped Meridianal Tris（8-Hydroxyquinoline） Aluminum Studied by First Principles Calculations

We theoretically investigate the electronic structure and spin polarization properties of Na-doped meridianal tris（S-hydroxyquinoline） aluminum （Alq3） by first principles calculations. It is found that the spin density is distributed mainly in the Alq3 part in the Alq3：Na complex. Electron charge transfer takes place from the Na atom to the Alq3 molecule, which induces asymmetric changing of the molecule bond lengths, thus the spin density distribution becomes asymmetric. Spin polarization of the complex originates from the preferable filling of the spin-split nitrogen and carbon p-orbitals because of the different bond length changes of the Aiq3 molecule upon Na doping.     

Enhancing visible-light photocatalytic activity of α-Bi2O3 via non-metal N and S doping

In recent years, some important research indicated that the visible-light activity of photocatalysts could be enhanced via incorporating p-block non-metal elements into the lattice. In this paper, we investigated the electronic structures of pure and different non-metal （C, N, S, F, Cl, and Br） doped α-Bi2O3 using first-principles calculations based on the density functional theory. The band structures, the electronic densities of states, and the effective masses of electrons and holes for doped α-Bi2O3 were obtained and analyzed. The N and S dopings narrowed the band gap and reduced the effective mass of the carriers, which are beneficial for the photocatalytic performance. The theoretical predication was further confirmed by the experimental results.     

Tm~(3+)掺杂锗碲酸盐玻璃的近2μm光谱性质

用高温熔融法制备了Tm2O3掺杂浓度为0.25,0.5,0.75,1,1.25,1.5 mol%的40 Ge O2-35Te O2-15Pb O-5Al2O3-2.5Ca O-2.5Sr O锗碲酸盐玻璃.热学性质测试表明该玻璃的转变温度为446℃,没有析晶峰.玻璃的最大声子能量约为750 cm-1.利用Judd-Ofelt理论计算了Tm3+的Judd-Ofelt参数Ωt(t=2,4,6)、不同浓度下Tm3+离子各激发态能级的自发辐射概率、荧光分支比以及辐射寿命等参数.采用808 nm波长抽运源测试了Tm3+离子的荧光光谱.发现掺杂浓度为1 mol%时约1.8μm处的荧光强度最强.根据Mc Cumber理论计算了3F4→3H6的发射截面,其峰值发射截面为6.5×10-21cm2.根据速率方程计算了玻璃中OH引起的Tm3+的3F4能级的无辐射弛豫速率,随着Tm3+浓度增加,OH对3F4能级的猝灭速率增加.这种玻璃有望研制成一种新型的约2μm的激光玻璃材料.     

Enhancement of ferromagnetic resonance in Al203-doped CozFeAI Heusler alloy film prepared by oblique sputtering

Large and variable in-plane uniaxial magnetic anisotropy in a nanocrystalline （Co2FeA1）97.8（Al2O3）2.2 soft magnetic thin film is obtained by an oblique sputtering method without being induced by magnetic field or post anneaiing. The in-plane uniaxiai magnetic anisotropy varies from 50 Oe to 180 Oe （1 Oe=79.5775 A·m-1） by adjusting the sample＇s position. As a result, the ferromagnetic resonance frequency of the film increases from 1.9 GHz to 3.75 GHz.