碳点修饰石墨毡电极在ZnI_2溶液中的电化学性能

通过溶剂热法在石墨毡(GF)上制备碳点(CD),将其作为电极,在碘化锌(ZnI_2)电解液中测量其电化学性能,研究其作为ZnI_2储能器件的电极对储能器件性能的影响。主要通过不同制备时间的溶剂热法制备碳点,研究不同的制备时间对碳点制备的影响。对碳点修饰的石墨毡进行快速热退火,研究退火对石墨毡电极性能的影响。通过场发射扫描电子显微镜(FE-SEM)、X射线衍射仪(XRD)和喇曼光谱对电极表面进行了表征。通过循环伏安曲线(CV)、电化学阻抗谱(EIS)和计时电位法研究其电化学性能。研究结果表明,通过9 h、180℃下溶剂热法制备的CD修饰GF具有最好的电化学性能。     

ITO薄膜制备及RTA处理对发光器件特性的影响

采用射频反应磁控溅射生长铟锡氧化物(ITO)薄膜,通过X射线衍射(XRD)、透射光谱、四探针法及原子力显微镜(AFM)研究了生长条件、快速热退火(RTA)温度等对薄膜的晶化、透过率、电导率以及表面形貌的影响.以ITO/NPB/AlQ/Al结构的器件为例,讨论了不同的制备条件下ITO薄膜的表面效应对电致发光(EL)的影响,通过EL光谱表征发现,对ITO退火处理后,器件的相对发光强度明显增加,衰减速度减慢,器件的EL光谱有明显的变化.通过进一步分析认为,这是由于ITO薄膜表面的变化引起功函数的改变,从而引起电场重新分布造成的.     

X射线光电子能谱法研究In_(0.53)Ga_(0.47)As基Er_2O_3薄膜的能带排列

采用分子束外延(MBE)法在In_(0.53)Ga_(0.47)As衬底上沉积了金属Er薄膜,后经氧气退火得到Er_2O_3薄膜。台阶仪测得该Er_2O_3薄膜厚约10 nm。X射线光电子能谱(XPS)显示,采用此方法得到的Er_2O_3薄膜符合化学计量比。原子力显微镜测试结果显示,该薄膜表面平整。采用X射线光电子能谱同时测得Er 4d、In 3d和O1s的芯能级谱、Er_2O_3的价带谱以及O1s的能量损失谱,从而得到Er_2O_3的禁带宽度以及Er_2O_3与In_(0.53)Ga_(0.47)As衬底之间的价带偏移和导带偏移,数值分别为(5.95±0.30)eV、(-3.01±0.10)eV和(2.24±0.30)eV。通过X射线光电子能谱方法得到了Er_2O_3/In_(0.53)Ga_(0.47)As异质结的能带排列。从能带偏移的角度来看,上述研究结果表明,Er_2O_3是一种非常有应用前景的In_(0.53)Ga_(0.47)As基栅介质材料。     

基于有限域GF上圆锥曲线的公钥密码算法

圆锥曲线密码学是一种新型的公钥密码学,迄今对圆锥曲线密码学的研究成果都是以有限域GF(p)上的圆锥曲线为基础的.本文将有限域GF(p)上的圆锥曲线C(GF(p))推广为有限域GF(2ⁿ)上的圆锥曲线C(GF(2ⁿ)),证明了圆锥曲线C(GF(2ⁿ))上的点和加法运算构成有限交换群(C(GF(2ⁿ)),),并给出了圆锥曲线群(C(GF(2ⁿ)),)的阶的计算.此外,提出了使用有限域GF(2ⁿ)上的圆锥曲线群构造公钥密码系统,并给出了ElGamal加密方案和数字签名算法(DSA)在圆锥曲线C(GF(2ⁿ))上模拟的算法,最后分析其安全性.     

GaN衬底上纳米点阵列的制备及其应用研究

研究了纳米掩膜在材料外延生长及器件制备中的应用.通过电化学腐蚀和电子束蒸发方法在GaN表面生成Ni和SiO<,2>纳米点阵列,经过等离子体刻蚀在Ni/GaN模板上形成GaN纳米锥形结构;利用氢化物气相外延(HVPE)方法,在SiO<,2>/GaN模板上制备厚膜GaN材料.X射线衍射(XRD)和光致发光(PL)谱测试表明...     

聚焦离子束切割法制备多层膜X射线波带片

X射线波带片是X射线显微成像系统中用于聚焦及成像的核心元件,提高波带片性能参数,更利于X射线显微成像技术的广泛应用。选择可精确控制厚度的原子层沉积(ALD)法结合聚焦离子束(FIB)切割法制备出大高宽比X射线波带片结构,即用原子层沉积法在光滑的钨丝表面交替沉积Al2O3/HfO2多层膜,其总层数为360,最外层膜宽度为10 nm。聚焦离子束的加速电压设定为30 kV,先利用束流为1 000 pA的离子束流将Al2O3/HfO2多层膜切割成设计厚度的薄片,再利用束流为350 pA的离子束流对切割的截面进行抛光,最后得到厚度为50μm、最外层膜宽度为10 nm的大高宽比X射线波带片结构。     

基于GF(2~n)的ECC协处理器芯片设计

文章讨论了定义在GaloisField(GF)2有限域上椭圆曲线密码体制(ECC)协处理器芯片的设计。首先在详细分析基于GF(2n)ECC算法的基础上提取了最基本和关键的运算,并提出了通过协处理器来完成关键运算步骤,主处理器完成其它运算的ECC加/解密实现方案。其次,进行了加密协处理器体系结构设计,在综合考虑面积、速度、功耗的基础上选择了全串行方案来实现GF(2n)域上的乘和加运算。然后,讨论了加密协处理器芯片的电路设计和仿真、验证问题。最后讨论了芯片的物理设计并给出了样片的测试结果。     

Nd:KGW多波长激光晶体生长与光谱特性

采用顶部籽晶熔盐法(TSSG)生长出掺钕钨酸钾钆Nd:KGd(WO4)2(Nd:KGW)多波长激光晶体.XRD分析了晶体结构,通过X射线荧光分析,检测到晶体中含有W,K,Gd和Nd元素.测试了晶体的红外、拉曼和紫外可见吸收光谱,计算了晶体中Nd3+离子的吸收截面积.     

铝掺杂氧化锌薄膜在玻璃衬底上的RF反应共溅射低温织构生长

以金属锌( Zn)和铝( Al)为靶材采用射频( RF)反应共溅射技术在低温( 2 0 0℃)玻璃衬底上沉积了铝掺杂氧化锌( Zn O∶Al)薄膜.运用扫描电子显微镜( SEM)、能量色散X射线谱( EDX)、表面轮廓仪(α- Step)、X射线衍射( XRD)和双光束紫外-可见光谱仪( U V- VIS)等分别对沉积样品的表面和断面的形貌结构、组成成分和光学特性进行了分析表征.研究了反应气体氧与氩流量比( O2 / Ar)和RF溅射功率对沉积样品的生长速率、结构特征和光电学性质的影响.结果表明,薄膜的成长速率强烈依赖于RF溅射功率,而薄膜的结构形貌和成分的化学配比则主要由反应气体流量比O2 / Ar     

CaMoO4纳米颗粒的合成、表征及电化学性能

二元金属氧化物是一种重要的电极材料,改进其电化学特性对提升电池容量的性能具有重要意义.采用水热法成功合成CaMoO4纳米颗粒.利用X射线衍射仪(XRD)、能量色散X射线光谱仪(EDS)以及扫描电子显微镜(SEM)对CaMoO4纳米材料的结构、形貌以及元素组成进行了详细的研究.在三电极系统下对CaMoO4电极材料进行循环...     

Bifunctional Heterostructure Assembly of NiFe LDH Nanosheets on NiCoP Nanowires for Highly Efficient and Stable Overall Water Splitting

3D hierarchical heterostructure NiFe LDH@NiCoP/NF electrodes are prepared successfully on nickel foam with special interface engineering and synergistic effects. This research finds that the as‐prepared NiFe LDH@NiCoP/NF electrodes have a more sophisticated inner structure and intensive interface than a simple physical mixture. The NiFe LDH@NiCoP/NF electrodes require an overpotential as low as 120 and 220 mV to deliver 10 mA cm^?2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1 m KOH, respectively. Tafel and electrochemical impedance spectroscopy further reveal a favorable kinetic during electrolysis. Specifically, the NiFe LDH@NiCoP/NF electrodes are simultaneously used as cathode and anode for overall water splitting, which requires a cell voltage of 1.57 V at 10 mA cm^?2. Furthermore, the synergistic effect of the heterostructure improves the structural stability and promotes the generation of active phases during HER and OER, resulting in excellent stability over 100 h of continuous operation. Moreover, the strategy and interface engineering of the introduced heterostructure can also be used to prepare other bifunctional and cost‐efficient electrocatalysts for various applications.     

CaMoO4/GO复合材料的制备及其超级电容器性能

采用水热法成功合成了CaMoO₄/氧化石墨烯(GO)纳米复合材料。通过材料的表面形貌、晶体结构和电化学性能研究合成的纳米复合材料。结果表明,CaMoO₄/GO电极在电流密度0.5 A/g时比电容高达571.82 F/g,并且在1 A/g的电流密度下,经过1000次循环后的比电容保持率仍为84%。为了测试电极材料的实际应用效果,全固态超级电容器(ASC)分别使用CaMoO₄/GO和活性炭(AC)作为正极和负极进行组装。组装的ASC在功率密度1710.3 W/kg下显示出25.18 W·h·kg^-1的能量密度,并且能通过串联4个ASC为红色发光二极管供电。上述结果表明CaMoO₄/GO电极材料在高性能储能设备的应用中具有非常大的潜力。     

Mo-/Co-N-C Hybrid Nanosheets Oriented on Hierarchical Nanoporous Cu as Versatile Electrocatalysts for Efficient Water Splitting

Designing robust and cost-effective electrocatalysts based on Earth-abundant elements is crucial for large-scale hydrogen production through electrochemical water splitting. Here, nitrogen-doped carbon engrafted Mo₂N/CoN hybrid nanosheets that are seamlessly oriented on hierarchical nanoporous Cu scaffold (Mo-/Co-N-C/Cu), as highly efficient electrocatalysts for alkaline hydrogen evolution reaction are reported. The constituent heterostructured Mo₂N/CoN nanosheets work as bifunctional electroactive sites for both water dissociation and adsorption/desorption of hydrogen intermediates while the nitrogen-doped carbon bridges electron transfers between electroactive sites and interconnective Cu current collectors by making use of Mo-/Co-N-C bonds and intimate C/Cu contacts at interfaces. As a consequence of unique architecture having electroactive sites to be sufficiently accessible, self-supported nanoporous Mo-/Co-N-C/Cu hybrid electrodes exhibit outstanding electrocatalysis in 1 m KOH, with a negligible onset overpotential and a low Tafel slope of 47 mV dec⁻¹. They only take overpotential of as low as 230 mV to reach current density of 1000 mA cm⁻². When coupled with their electro-oxidized derivatives that mediate efficiently the oxygen evolution reaction, the alkaline water electrolyzer can achieve ≈100 mA cm⁻² at 1.622 V in 1 m KOH electrolyte, ≈0.343 V lower than the device constructed with commercially available Pt/C and Ir/C nanocatalysts immobilized on nanoporous Cu electrodes.     

二硫化钼催化析氢电极的构筑及其性能研究

针对目前MoS₂作为析氢催化剂时存在的活性位点数目少且材料导电性能差等问题,文中通过液相超声剥离法以及离心处理制备得到MoS₂/PVP分散液。PVP的辅助剥离作用使得剥离得到的MoS₂纳米片尺寸大幅减小,提高了MoS₂催化析氢活性位点的丰度;MoS₂在PVP辅助剥离过程中发生了2H相到1T相的转变,同样增强了催化析氢活性。文中选用含有导电铜层的PI基片作为电极基底,利用喷墨印刷技术将MoS₂/PVP催化剂固载于导电基底上制得催化析氢电极。该电极在10 mA·cm ^-2处的过电位为77 mV,Tafel斜率为65 mV·dec ^-1,这一结果表明该催化电极具有高催化活性。     

Bismuth-doped Pb1-xSnxTe diode lasers with low-threshold currents

Diode lasers have been fabricated from Bi-doped Pb1-xSnxTe with0.24 leq x leq 0.27, which have threshold current densities as low as 1400 A.cm^-2at 77°K and 71 A.cm^-2at 12°K, whereas diodes fabricated from undoped Pb1-xSnxTe> in this composition range did not exhibit laser action for current densities up to 30 000 A.cm^-2at 77°K and had threshold current densities greater than 200 A.cm^-2at 12°K. Bi doping also results in a reduction in the annealing times required to form suitablep-njunctions from several weeks to a few days. These effects can be tentatively related to an increased electron concentration in then-type layer due to the addition of Bi, a donor impurity. A curve ofEgversusxfor0 leq x leq 0.4, which agrees with predictions, is presented.     

Fabrication and characterization of metal-oxide-semiconductorfield-effect transistors and gated diodes using Ta2O5 gate oxide

N-channel metal oxide semiconductor field effect transistors (MOSFETs) using Ta₂O₅, gate oxide were fabricated. The Ta₂O₅ films were deposited by plasma enhanced chemical vapor deposition. The I_DS-V_DS and I_DS-V_GS characteristics mere measured. The electron mobility was 333 cm²/V·s. The subthreshold swing was 73 mV/dec. The interface trapped charge density, the surface recombination velocity, and the minority carrier lifetime in the field-induced depletion region measured from gated diodes were 9.5×10¹² cm^-2 eV^-1, 780 cm/s and 3×10^-6 sec, respectively. A comparison with conventional MOSFETs using SiO₂ gate oxide was made     

Plasma-Enhanced Atomic Layer Deposition of Amorphous Ga2O3 for Solar-Blind Photodetection

Wide-bandgap gallium oxide (Ga₂O₃) is one of the most promising semiconductor materials for solar-blind (200 nm to 280 nm) photodetection. In its amorphous form, amorphous gallium oxide (a-Ga₂O₃) maintains its intrinsic optoelectronic properties while can be prepared at a low growth temperature, thus it is compatible with Si integrated circuits (ICs) technology. Herein, the a-Ga₂O₃ film is directly deposited on pre-fabricated Au interdigital electrodes by plasma enhanced atomic layer deposition (PE-ALD) at a growth temperature of 250 °C. The stoichiometric a-Ga₂O₃ thin film with a low defect density is achieved owing to the mild PE-ALD condition. As a result, the fabricated Au/a-Ga₂O₃/Au photodetector shows a fast time response, high responsivity, and excellent wavelength selectivity for solar-blind photodetection. Furthermore, an ultra-thin MgO layer is deposited by PE-ALD to passivate the Au/a-Ga₂O₃/Au interface, resulting in the responsivity of 788 A/W (under 254 nm at 10 V), a 250-nm-to-400-nm rejection ratio of 9.2×103, and the rise time and the decay time of 32 ms and 6 ms, respectively. These results demonstrate that the a-Ga₂O₃ film grown by PE-ALD is a promising candidate for high-performance solar-blind photodetection and potentially can be integrated with Si ICs for commercial production.     

Optical parametric interactions in 3-methyl-4-nitropyridine-1-oxide (POM) single crystals

Various configurations of three-wave parametric interactions are reported at the picosecond time scale, in 3-methyl-4-nitropyridine-1-oxide (POM) single crystals. Wavelength dispersion of phase-matched second-harmonic generation orientation is experimentally established within the0.8-2 mum range using as fundamental input the idler and signal emissions of a picosecond LiIO3parametric emitter. Efficient parametric amplification is demonstrated: at degeneracy a gain of 10³is measured for a pump intensity of 130 MW . cm^-2at 0.53 μm and an input signal of 5 kW . cm^-2at 1.06 μm. Single pass parametric emission is achieved, for the first time in an organic crystal, yielding 200 kW . cm^-2at 1.06 μm, using the frequency-doubled output of a passively mode-locked YAG system. Both dispersion and interaction length dependence of the experimental gain are accounted for.     

Nonprecious Intermetallic Al7Cu4Ni Nanocrystals Seamlessly Integrated in Freestanding Bimodal Nanoporous Copper for Efficient Hydrogen Evolution Catalysis

Tremendous demands for renewable hydrogen generated from water splitting have stimulated intensive research on developing earth‐abundant, non‐noble, and versatile metal catalysts toward the hydrogen evolution reactions (HER). Here, self‐supported Cu‐Ni‐Al hybrid electrodes that are composed of electroactive Al₇Cu₄Ni@Cu₄Ni core/shell nanocrystals seamlessly integrated in self‐supported 3D bimodal nanoporous Cu skeleton (Bi‐NP Cu/Al₇Cu₄Ni@Cu₄Ni) as robust HER electrocatalysts in alkaline electrolyte are reported. As a result of the proper architecture, in which the Bi‐NP Cu skeleton not only facilitates both electron and electrolyte transports but also provides high specific surface areas to fully use high electrocatalytic activity of Al₇Cu₄Ni@Cu₄Ni core/shell nanocrystals, the Bi‐NP Cu/Al₇Cu₄Ni@Cu₄Ni hybrid catalysts exhibit a low onset overpotential of 60 mV and a small Tafel slope of 110 mV dec^?1, enabling the catalytic current density of 10 mA cm^?2 at a low overpotential of 139 mV. The highly stable electrochemical performance makes them promising candidates as cathode catalysts in alkaline‐based devices.     

Low Dit, thermodynamically stable Ga2O3-GaAs interfaces: fabrication, characterization, and modeling

Thermodynamically stable, low D_it amorphous Ga₂ O₃-(100) GaAs interfaces have been fabricated by extending molecular beam epitaxy (MBE) related techniques. We have investigated both in situ and ex situ Ga₂O₃ deposition schemes utilizing molecular beams of gallium oxide. The in situ technique employs Ga₂O₃ deposition on freshly grown, atomically ordered (100) GaAs epitaxial films in ultrahigh vacuum (UHV); the ex situ approach is based on thermal desorption of native GaAs oxides in UHV prior to Ga₂O₃ deposition. Unique electronic interface properties have been demonstrated for in situ fabricated Ga₂O₃-GaAs interfaces including a midgap interface state density D_it in the low 10¹⁰ cm^-2 eV^-1 range and an interface recombination velocity S of 4000 cm/s. The existence of strong inversion in both n- and p-type GaAs has been clearly established. We will also discuss the excellent thermodynamic and photochemical interface stability. Ex situ fabricated Ga₂O₃-GaAs interfaces are inferior but still of a high quality with S=9000 cm/s and a corresponding D_it in the upper 10¹⁰ cm^-2 eV^-1 range. We also developed a new numerical heterostructure model for the evaluation of capacitance-voltage (C-V), conductance-voltage (G-V), and photoluminescence (PL) data. The model involves selfconsistent interface analysis of electrical and optoelectronic measurement data and is tailored to the specifics of GaAs such as band-to-band luminescence and long minority carrier response time τ_R. We will further discuss equivalent circuits in strong inversion considering minority carrier generation using low-intensity light illumination