航天用氮化镓材料的研究进展

氮化镓(GaN)材料由于具有优良的电学特性而受到了广泛的关注,有望在航天工程中获得重要应用。本文首先对GaN材料的特性进行了简要阐述,进而对基于GaN的高电子迁移率晶体管(AlGaN/GaN HEMTs)、空间太阳能电池、紫外探测器等的研究和应用现状进行了梳理及分析,最后从新型GaN器件的开发、空间环境适应性评价、GaN器件的加固等角度给出了航天器用GaN材料及器件的发展方向和建议。     

国内氮化镓半导体材料及应用专利布局现状

正氮化镓(GaN)半导体材料作为第3代半导体的核心材料,自20世纪90年代开始用于LED显示领域,目前已广泛应用于普通照明及显示领域。而从2010年第1个GaN功率器件投入市场后,GaN功率器件又逐渐成为半导体功率器件主流。2021年随着各国5G通讯、消费性电子、工业能源转换及新能源车等需求拉升,     

氮化镓材料在传感器中的应用

<正>氮化镓(GaN)是直接宽带隙半导体材料,属于第3代半导体。相较于硅、砷化镓等,GaN的禁带宽度更大、击穿电场强度更高,具有更高的电子饱和度和漂移速率、更强的抗辐照能力以及较强的化学稳定性。氮化镓材料与硅、砷化镓材料的电子性能对比如表1所示。目前GaN制备工艺成熟,已经能够利用GaN制造出结构复杂的器件。GaN基紫外探测器由于在可见光和红外光范围内都没有响应,其在可见光和红外光背景下的紫外光探测具     

我国在非极性GaN材料研究中取得进展

在国家863项目和中国科学院创新工程的支持下,中科院半导体研究所曾一平研究员带领的课题,采用自行研制的HVPE氮化物生长系统,通过在m面蓝宝石上磁控溅射生长薄层的ZnO缓冲层,进而外延生长获得了非极性GaN厚膜材料,该材料具有较低的位错密度,适合开发用于LED、LD等氮化物发光器件的衬底材料,同时对比实验表明,薄层的ZnO对于形成非极性GaN起到了至关重要的作用,     

电子材料

正美国拟开发全球首个氮化镓处理器氮化镓(GaN)材料不仅成为了电子学的新一代半导体,还可能是太空领域的基础材料。亚利桑那州立大学(ASU)电子与计算机工程师赵宇杰(Yuji Zhao)计划研发出第一个氮化镓处理器,这可能会彻底改变未来的太空探索任务。氮化镓是通常用于制作发光二极管(LEDs)的半导体化合物。这种材料的导     

第3代半导体材料GaN基微波功率器件研究和应用进展

<正>微波功率器件是指工作频段在300M～300GHz这个微波波段内的电子器件,主要用以实现微波功率的发射和放大、控制和接收等功能,是现代相控阵雷达、移动通讯基站等的核心部件。目前微波功率器件的主流产品主要基于第1代半导体材料硅(Si)、锗(Ge)和第2代半导体材料砷化镓(GaAs)、磷化铟(InP)。20世纪90年代,基于第3代宽禁带半导体材料氮化镓(GaN)的高频、大功率微波器件     

三菱化学宣布将优先投资白色LED及车载锂电池材料两大领域

据报道,三菱化学日前召开了经营方针说明会,宣布今后将优先投资白色LED及车载锂离子充电电池材料两大领域。白色LED领域包括GaN(氮化镓)底板及荧光体等材料、以及照明器具及液晶电视用     

第3代半导体材料在光电器件方面的发展和应用

<正>一、第3代半导体材料概述第3代半导体材料是继第1代半导体材料和第2代半导体材料之后,近20年刚刚发展起来的新型宽禁带半导体材料。第3代半导体材料以氮化镓(GaN)、碳化硅(SiC)、氧化锌(ZnO)和氮化铝(AlN)等宽禁带化合物半导体为代表,其具有高击穿电场、高热导率、高电子饱和速率及高抗辐射能力等特点,因而更适合于制作高温、高频、抗辐射及大功率器件,在光电子领     

基于干法刻蚀技术的氮化镓MEMS加工工艺(英文)

氮化镓(GaN)材料已成功应用于光电子器件、高频功率器件等领域.近年来,由于GaN优异的材料特性,例如机械、热、化学稳定性以及生物兼容性等,使基于GaN的微机电系统(MEMS)得到了学术界的广泛关注.针对氮化镓MEMS结构的有效的图形化及释放技术是工艺研究的重点.设计、采用了一种全干法刻蚀技术,实现了(111)晶向硅衬底上的氮化镓基MEMS微结构的加工制造.利用提出的工艺方案,实现了多种悬浮GaN微结构的加工与测试表征实验.通过电子扫描显微镜(SEM)和光学轮廓仪进行了基本形貌表征;利用微拉曼光谱实验进行了加工结构的残余应力表征.     

集成电子薄膜材料研究进展

首先分析了当前我国电子信息产业的现状,特别是电子材料与元器件行业的状况,结合国际上电子信息技术的发展趋势,阐述了研究集成电子材料的重要意义.文章结合作者的工作主要介绍了介电/GaN集成电子薄膜生长控制与性能研究情况,采用TiO2(诱导层)/MgO(阻挡层)组合缓冲层的方法控制介电/GaN集成薄膜生长取向、界面扩散,保护GaN基半导体材料的性能,降低介电/GaN集成薄膜界面态密度,建立界面可控的相容性生长方法.通过集成结构的设计与加工,研制出介电增强型GaN HEMT器件、高耐压GaN功率器件原型以及一体化集成的微波电容、变容管、压控振荡器、混频器等新型元器件.     

Nitrogen,Fluorine, and Boron Ternary Doped Carbon Fibers as Cathode Electrocatalysts for Zinc–Air Batteries

Zinc–air batteries with high‐density energy are promising energy storage devices for the next generation of energy storage technologies. However, the battery performance is highly dependent on the efficiency of oxygen electrocatalyst in the air electrode. Herein, the N, F, and B ternary doped carbon fibers (TD‐CFs) are prepared and exhibited higher catalytic properties via the efficient 4e⁻ transfer mechanism for oxygen reduction in comparison with the single nitrogen doped CFs. More importantly, the primary and rechargeable Zn–air batteries using TD‐CFs as air–cathode catalysts are constructed. When compared to batteries with Pt/C + RuO₂ and Vulcan XC‐72 carbon black catalysts, the TD‐CFs catalyzed batteries exhibit remarkable battery reversibility and stability over long charging/discharging cycles.     

An experimental study on thermal diffusivity of nanocrystalline Ag

Thermal diffusivity (TD) and its relation to the microstructure of nanocrystalline Ag (n-Ag), synthesized by inert-gas condensation and in-situ compaction, was investigated by photoacoustic technique. The results indicated that a dramatic decrease of TD in n-Ag (which is about 27% that of p-Ag for the n-Ag with grain size 20 nm) is related to its small grain size and large volume fraction of interfacial component, and originates mainly from reduction of its thermal conductivity. Annealing experiments showed that TD is not only affected by its grain size, but also strongly dependent on the microstructure of the interfaces. The increase of TD with increasing grain size can be explained by attributing it mainly to the rise of effective electron density; while increasing TD by annealing where no substantial grain growth occurred, reflects an increase of electron transmission coefficient during annealing, which could also lead to a rise in effective electron density. In addition, the prompt decrease of TD with decreasing specimen density as it is lower than 93% could be reasonably attributed to the increasing number of extended boundaries in n-Ag.     

Al-5.4Zn-2.6Mg-1.4Cu合金板材的低周疲劳行为

进行Al-5.4Zn-2.6Mg-1.4Cu合金板材的室温低周疲劳实验,对比研究了轴向平行于轧制方向(RD方向)和垂直于轧制方向(TD方向)试样的低周疲劳行为。结果表明：对于0.4%~0.8%的外加总应变幅,RD和TD方向合金试样的循环应力响应行为均呈现出循环稳定;对于相同的外加总应变幅,TD方向合金的循环应力幅值高于RD方向,而RD方向合金的疲劳寿命高于TD方向。对于RD和TD方向,Al-5.4Zn-2.6Mg-1.4Cu合金的塑性应变幅、弹性应变幅与载荷反向周次均呈线性关系。在低周疲劳加载条件下,裂纹在疲劳试样的自由表面以穿晶方式萌生和扩展。     

Effects of marketing–manufacturing integration across stages of new product development on performance

Our understanding on the benefits of marketing–manufacturing integration (MMI) across various stages of new product development (NPD) process is limited. Based on the resource-based view of a firm, this study empirically examines the direct and interactive effects of MMI in four stages of NPD process on three dimensions of new product performance. Survey data from 214 completed NPD projects in Chinese manufacturing firms are employed to test the developed hypotheses using hierarchical regression. The results indicate that greater MMI in each stage is, respectively, associated with faster NPD speed. Stronger MMI in business/market opportunity analysis (BMA), technical development (TD) and product testing (PT) stage is, respectively, associated with higher NPD cost efficiency. Higher MMI in BMA and PT stage is, respectively, associated with better market performance. In addition, the interactions of MMI in BMA and TD stages and MMI in PT and product commercialization (PC) stages have positive effects on NPD speed and NPD cost efficiency, while the interaction of MMI in BMA and PC stages has negative effects on NPD speed and NPD cost efficiency. The interaction of MMI in BMA, TD and PC stages is positively related to market performance; surprisingly, the interactions of MMI in BMA, TD and PT stages and MMI in BMA, PT and PC stages are negatively related to market performance. These findings have important implications for research and practice in both the cross-functional integration and NPD areas.     

Data service oriented networking analysis of TD LTE system

移动互联网和物联网的发展带来数据业务的蓬勃发展,对移动系统带宽需求激增,促使运营商大力发展面向数据业务的LTE技术,特别是采用非对称频谱的TD-LTE技术。本文分析TD-LTE系统组网应考虑的内容,研究TD-LTE系统本身及与TD-SCDMA系统进行同频组网的可行性,给出面向数据业务的TD-LTE系统组网总体建议。     

Development of stabilized tenofovir disoproxil tablet: degradation profile,stabilization, and bioequivalence in beagle dogs

The purpose of this study was to develop a hydrolysis-resistant optimized oral formulation of tenofovir disoproxil (TD) using a stabilizer. To develop a stabilized TD tablet bioequivalent to the commercial TD fumarate (TDF, Viread^®) tablet, TD free base was prepared and its degradation profile and stability were investigated. The TD tablet showed antiviral activity, but its absorption was limited in the intestinal tract because of premature degradation. The drug subjected to severe conditions for the stress test was catalyzed under neutral, basic, oxidative, and thermolytic conditions, whereas it was comparatively stable under acidic, photolytic, and humid states. The compatibility study showed that sodium bisulfite (SB) stabilized TD by preventing its degradation in aqueous and 3% peroxide solutions compared with the unstabilized TD. According to the stability analysis and degradation profile, four TD tablet formulations were prepared. The selected TD tablets were composed of non-hygroscopic excipients (lipophilic-fumed silica, anhydrous lactose, and microcrystalline cellulose [MCC]), SB, croscarmellose sodium (CCS), and hydrogenated castor oil (HCO), and were manufactured using a dry granulation method because of their hydrolytic properties. The stabilized TD tablet showed similar dissolution properties as the TDF (Viread^®) reference tablet in pH 1.2, 4.0, and 6.8 and water. Moreover, the lower degradation rate of the tablet in simulated gastrointestinal fluid demonstrated that its intestinal absorption might have improved owing to prevention of its enzymatic hydrolysis and the pH effect. Finally, the formulated TD tablet was bioequivalent to the TDF (Viread^®) reference tablet in beagle dogs.     

茶粉/聚丙烯复合材料自然老化性能

为高值化利用茶产业剩余物,拓宽木塑复合材料中植物纤维来源,以茶粉（TD）为有机增强相,聚丙烯（PP）为基体,采用开炼-注塑工艺制备了TD/PP复合材料;为研究其户外应用及老化机制,采用户外自然老化形式考察了老化时间对TD/PP复合材料力学性能、材色及表面形貌的影响,并用FTIR分析了其老化机制。结果表明:与木材纤维相比,TD中纤维素含量更少,而各种形式的抽提物含量要高很多,纤维长径比更小。户外自然老化8个月后,TD/PP复合材料的亮度变化值、红绿轴色品指数变化值、黄蓝轴色品指数变化值及色差值分别为37.64、-10.40、-3.38和39.19;TD/PP复合材料的弯曲、缺口冲击强度、弯曲模量及硬度值分别降低了38.7%、42.4%、41.4%和9.14%。FTIR分析表明,在户外自然老化环境中,TD/PP复合材料中的PP分子链和TD中木质素组分发生了光照降解。SEM照片显示,随户外自然老化时间延长,TD/PP复合材料表面出现裂纹,且裂纹数量逐渐增多,深度和宽度增大,并且局部地方出现粉化现象。      

Separation of thermal and autogenous deformation at varying temperatures using optical fiber sensors

Common, high and ultra high performance concretes undergo autogenous deformation (AD) when hardening. Deformations are often measured in specimens cured in so-called autogenous conditions, where fully coupled thermal deformation (TD) and AD are the only deformations. Therefore, in autogenous conditions, a decoupling technique must be used to separate the contributions of TD and AD. This paper presents a new technique using optical fiber sensors in specimens that are cured at varying temperatures and in autogenous conditions. Degree of reaction indexes (DRI), sometimes called maturity and equivalent time, are employed to separate TD and AD. The paper begins with a summary of the application of DRI to decoupling techniques, with particular focus on theoretical limits and potential for deformation separation. Current practices related to decoupling and modeling of the thermal and autogenous deformation are evaluated through comparison with experiments. Results confirm that testing improves the accuracy of estimation of values for the thermal expansion coefficient (TEC). Moreover, since AD swelling is detected for all tests, models that include the assumption that AD is exclusively shrinkage are not appropriate for describing AD at varying temperatures.     

Orientation dependent behavior of tensile-creep deformation of hot rolled Ti65 titanium alloy sheet

The mill products like sheet always have one or more severe textures inevitably,and its effect on mechan-ical properties is not a negligible issue.The orientation dependent tensile-creep behavior induced by rolling texture of Ti65 titanium alloy sheet has been systematically investigated at 650℃.There are some anisotropic characteristics between TD and RD of Ti65 sheet.The UTS and TYS of TD are higher than RD at 650℃.Besides,the creep endurance time of TD(172.6-174.5 h)is about three times longer than RD(55.6-65.1 h)at 650℃and 240 MPa.Moreover,the grains are inclined to form Texture Ⅲ(1 2(1)6)[1(2)11]and(01(1)3)[1(2)11]after creep along with TD,but to form Texture I((1)2-(1)0)[10-(1)0]after creep along with RD.Finally,the crack initiation site is different during creep in TD and RD.The reason for anisotropic properties of tensile and creep has been summarized in two aspects:(ⅰ)the change of the SFs(Schmid factors)value between TD and RD;(ⅱ)the difference of creep mechanism between TD(grain boundary sliding)and RD(dislocation slip).Anisotropy of Ti65 sheet should be fully considered to increase structural efficiency in the engineering design and application.     

Orientations of nuclei during static recrystallization in a cold-rolled Mg-Zn-Gd alloy

The static recrystallization process of a cold-rolled Mg-Zn-Gd alloy was tracked by a quasi-in-situ electron backscatter diffraction method to investigate the orientations of nuclei.The results show that orientation distribution of nuclei is associated with nucleation mechanism.The continuous static recrystallization nuclei display similar orientations to the parent grains with TD orientation.Differently,discontinuous static recrystallization nuclei formed within the parent grains(TD-45~0 orientation) show random orientations and a variety of misorientation angles but preferred axes <5273> or <5270>.Interestingly,a special oriented nucleation is found.Discontinuous static recrystallization nuclei originated from boundaries of the parent grain(TD-70° orientation) show concentrated TD orientations in another side due to the preferred misorientation relationship 70°<1120>(∑18 b).It is speculated that these two special misorientation relationships are related to the dislocation type.