聚乙烯醇掺杂对二维MoS2晶体管电学性能的影响

采用机械剥离法得到二维MoS2材料并将其转移到SiO2/Si衬底上,采用光刻、剥离工艺制备出二维MoS2晶体管.将二维MoS2晶体管浸泡在不同质量浓度的聚乙烯醇(PVA)溶液中,然后旋涂成膜并退火实现掺杂.对掺杂前后二维MoS2晶体管的电学性能进行测试.测试结果显示,当PVA溶液质量浓度为0.5％、1％和2％时,掺杂后的二维MoS2晶体管开态电流提高到3倍、3.6倍和10倍,有效电子迁移率提高到1.7倍、2.8倍和4.3倍,开态电阻降低了一个数量级以上.由于掺杂层的覆盖,二维MoS2晶体管的稳定性有了显著提高,暴露在空气中30 d后未观察到电学性能有明显退化.研究结果表明,可以通过控制PVA溶液的质量浓度对二维MoS2晶体管的掺杂浓度进行调控,从而影响其电学性能.     

动态应力对AlGaN/GaN HEMT性能的影响

AlGaN/GaN高电子迁移率晶体管(HEMT)器件在实际应用过程中经常受到由于振动、热胀冷缩等原因引起的动态应力.为了研究动态应力对器件性能带来的影响,利用自主设计的应力机械装置对AlGaN/GaN HEMT芯片持续施加峰值大小为150 MPa,频率为3 Hz的交变应力.施加应力过程中,每隔一定的应力周期对器件进行电学特性测量,得到了不同应力周期下的输出特性曲线和转移特性曲线.研究分析了随着应力周期的增加输出电流和跨导的变化,研究结果表明,器件的输出电流和跨导随着施加动态应力周期的增加而减小.随着动态应力的加载,器件将产生缺陷,是器件发生退化的原因.     

质子辐照对超辐射发光二极管性能的影响

用能量分别为350keV和1MeV,注量为1×1012和1×1013p/cm2的质子对超辐射发光二极管(SLD)进行辐照,对辐照前后器件的光学和电学性能进行了测试.结果表明,在相同注量辐照的条件下,350keV与1MeV能量质子辐照引起的辐照损伤相比,前者引起的出光功率的退化更大,造成的辐照损伤更加严重.采用TRIM程序对质子入射到器件材料中的射程分布进行了模拟,初步探讨了SLD在350keV和1MeV能量质子辐照下的损伤效应.     

Laser Assisted Solution Synthesis of High Performance Graphene Supported Electrocatalysts

Simple, yet versatile, methods to functionalize graphene flakes with metal (oxide) nanoparticles are in demand, particularly for the development of advanced catalysts. Herein, based on light‐induced electrochemistry, a laser‐assisted, continuous, solution route for the simultaneous reduction and modification of graphene oxide with catalytic nanoparticles is reported. Electrochemical graphene oxide (EGO) is used as starting material and electron–hole pair source due to its low degree of oxidation, which imparts structural integrity and an ability to withstand photodegradation. Simply illuminating a solution stream containing EGO and metal salt (e.g., H₂PtCl₆ or RuCl₃) with a 248 nm wavelength laser produces reduced EGO (rEGO, oxygen content 4.0 at%) flakes, decorated with Pt (≈2.0 nm) or RuO₂ (≈2.8 nm) nanoparticles. The RuO₂–rEGO flakes exhibit superior catalytic activity for the oxygen evolution reaction, requiring a small overpotential of 225 mV to reach a current density of 10 mA cm^?2. The Pt–rEGO flakes (10.2 wt% of Pt) show enhanced mass activity for the hydrogen evolution reaction, and similar performance for oxygen reduction reaction compared to a commercial 20 wt% Pt/C catalyst. This simple production method is also used to deposit PtPd alloy and MnO_x nanoparticles on rEGO, demonstrating its versatility in synthesizing functional nanoparticle‐modified graphene materials.     

温度暂态效应对光纤陀螺性能的影响及其减小措施

对温度暂态效应影响光纤陀螺零偏特性的机理进行了详细的理论分析,提出了几种消除温度暂态效应对光纤陀螺性能影响的方案,尤其是四极对称缠绕技术对提高光纤陀螺的温度特性具有更为明显的效果.     

Direct Graphene Transfer and Its Application to Transfer Printing Using Mechanically Controlled,Large Area Graphene/Copper Freestanding Layer

Direct graphene transfer is an attractive candidate to prevent graphene damage, which is a critical problem of the conventional wet transfer method. Direct graphene transfer can fabricate the transferred graphene film with fewer defects by using a polymeric carrier. Here a unique direct transfer method is proposed using a 300 nm thick copper carrier as a suspended film and a transfer printing process by using the polydimethylsiloxane (PDMS) stamp under controlled peeling rate and modulus. Single and multilayer graphene are transferred to flat and curved PDMS target substrate directly. With the transfer printing process, the transfer yield of a trilayer graphene with 1000 µm s^?1 peeling rate is 68.6% of that with 1 µm s^?1 peeling rate. It is revealed that the graphene transfer yield is highly related to the storage modulus of the PDMS stamp: graphene transfer yield decreases when the storage modulus of the PDMS stamp is lower than a specific threshold value. The relationship between the graphene transfer yield and the interfacial shear strain of the PDMS stamp is studied by finite‐element method simulation and digital image correlation.     

溶液浓度对SiC量子点光学性能的影响及表面修饰

采用可控化学腐蚀法制备SiC量子点,在原有腐蚀剂(氢氟酸和硝酸)的基础上添加适量的分析纯硫酸,一步法完成SiC量子点的表面修饰.采用光度计和Lince软件测量并计算了平均粒径5 nm的SiC量子点在不同溶液浓度下的光致发光谱和平均间距;采用傅里叶变换红外光谱仪对SiC量子点表面的功能团进行检测,对其表面亲水性基团耦合的机理进行分析.结果表明,随着SiC量子点溶液浓度的增大(4～12 μmol·L-1),其光致发光强度先增大后减小,且光致发光强度峰值出现在8 μmol·L-1时;SiC量子点表面形成亲水性基团的关键在于腐蚀法制备过程中超声空化环节所营造的局部高压高温环境.     

石墨烯烟幕红外干扰性能研究

氧化还原法制备了石墨烯,用透射电镜、扫描电镜、原子力显微镜、拉曼光谱、红外光谱等对石墨烯进行了表征,并在烟箱中对石墨烯烟幕的红外干扰性能进行了测试。结果表明,石墨烯烟幕对1.6～14mm红外连续光谱均表现出优异的消光能力,对3～5mm和8～14mm红外的质量消光系数最高达5.49 m~2/g和4.78 m~2/g,平均质量消光系数分别为3.91 m~2/g和3.25 m~2/g,干扰性能明显优于现有红外干扰烟幕材料。此外,石墨烯气溶胶悬浮性能良好,烟幕沉降速度不高于1.63×10~(-3) m/s。     

Photoquantum Hall Effect and Light‐Induced Charge Transfer at the Interface of Graphene/InSe Heterostructures

The transfer of electronic charge across the interface of two van der Waals crystals can underpin the operation of a new class of functional devices. Among van der Waals semiconductors, an exciting and rapidly growing development involves the “post‐transition” metal chalcogenide InSe. Here, field effect phototransistors are reported where single layer graphene is capped with n‐type InSe. These device structures combine the photosensitivity of InSe with the unique electrical properties of graphene. It is shown that the light‐induced transfer of charge between InSe and graphene offers an effective method to increase or decrease the carrier density in graphene, causing a change in its resistance that is gate‐controllable and only weakly dependent on temperature. The charge transfer at the InSe/graphene interface is probed by Hall effect and photoconductivity measurmentes and it is demonstrated that light can induce a sign reversal of the quantum Hall voltage and photovoltaic effects in the graphene layer. These findings demonstrate the potential of light‐induced charge transfer in gate‐tunable InSe/graphene phototransistors for optoelectronics and quantum metrology.     

石墨烯对波导耦合特性影响的研究

石墨烯材料因具有非常优异的电光特性而成为新一代光子器件中的重要材料.文章研究了石墨烯对于硅基、聚合物两种材料双矩形波导耦合特性的影响.研究结果表明,在双波导耦合器件中增加一层石墨烯能够起到改变耦合长度的作用,不同费米能级的石墨烯可以增大或减小双波导耦合器件的耦合长度.石墨烯对耦合特性的影响对于硅基和聚合物波导均适用.此研究结果对于基于石墨烯的波导器件的设计和应用具有一定的参考意义.     

高性能激光诱导石墨烯压力传感器的研究

为了保证在低成本、易制备的前提下提高激光诱导石墨烯压力传感器的性能,设计了一种石墨烯压力传感器的放大结构。表征了激光诱导石墨烯压力传感器的表面结构,分析了表面多孔泡沫结构对压阻效应的影响,采用COMSOL软件对传感器放大结构的受力情况进行仿真分析,得到在外界压力下石墨烯层的受力情况。选用3D打印方法制备树脂材料放大结构基底,在低成本的同时兼顾了轻质、高精度、高机械强度等性能。测试结果表明,压强在5～20 kPa范围内时,该放大结构的灵敏度较无放大结构提高了约43%。     

多设备级联对播出信号质量的影响及解决方案

就多设备级联对播出信号质量的影响进行了理论分析和论证,并指出在播出系统中引入键控混合放大器,使设备级联工作方式变为并联方式,从而提高播出质量.     

一种基于PKI的保密文件传输方案

首先对互联网络中信息安全传输的基本要求进行了分析,并简要地介绍了PKI（公钥基础设施）的基本概念、基本组成及运行模式,特别指出PKI技术能够为信息传输提供安全服务.然后着重提出了一种基于PKI技术的保密文件传输方案,该方案主要分为2个模块：身份认证模块和文件保密传输模块.通过这两个模块的有机结合,能较好地满足保密文件传输的要求,即该方案实现了安全文件传输的身份认证、保密性、完整性和不可否认性等要求.