AlGaN/GaN HEMT研制及特性分析

以蓝宝石为衬底研制出栅长1μm AlGaN/GaN HEMT．在室温下,测试该器件显示出良好的输出特性和肖特基伏安特性,最大跨导160mS/mm,栅压1V下饱和电流720mA/mm,击穿电压大于50V．分析了几个关键工艺对器件特性的影响,指出较大的欧姆接触电阻(3.19Ω·mm)限制了器件性能进一步提高,需提高肖特基接触的势垒高度．     

AlGaN/GaN HEMT在N2中高温退火研究

通过N2气氛中对蓝宝石衬底AlGaN／GaN HEMT在200～600℃退火1min和5min的多批实验,研究了在不同温度和时间退火冷却后器件直流参数的变化．对器件欧姆接触和肖特基接触在高温退火前后的特性进行了对比分析．确定出了最有利于高电子迁移率晶体管特性提高的退火温度为500℃．退火时间为5min．该条件退火后高电子迁移率晶体管最大跨导提高8．9%．肖特基栅反向漏电流减小2个数量级．阈值电压绝对值减小．退火后肖特基势垒高度提高．在减小栅泄漏电流的同时对沟道电子也有耗尽作用．这是饱和电流和阈值电压变化的主要原因．采用扫描电子显微镜观察肖特基退火后的形貌，500℃未发现明显变化．600℃有起泡现象．     

X 波段单级氮化镓固态放大器

利用自主研制的SiC 衬底的栅宽为2.5mm的AlGaN/GaN HEMT器件,设计完成了单级X波段氮化镓固态放大器模块．模块由AlGaN/GaN HEMT器件、偏置电路和微带匹配电路构成．采用金属腔体和测试夹具,保证在连续波下具有良好的接地和散热性能．利用双偏置电路馈电,并且采用独特的电容电阻网络和栅极串联电阻消除了低频和射频振荡．利用微带短截线完成了器件的输入输出匹配．在 8GHz频率及连续波情况下(直流偏置电压为 V_ds= 27V, V_gs= -4.0V),放大器线性增益为 5.6dB,最大效率为30.5％,输出功率最大可达 40.25dBm (10.5W),此时增益压缩为 2dB．在带宽为 500MHz内,输出功率变化为 1dB．     

P-GaN栅结构GaN基HEMT器件研究进展

增强型氮化镓(GaN)基高电子迁移率晶体管(high electron mobility transistor, HEMT)是高频高功率器件与开关器件领域的研究热点，P-GaN栅技术因具备制备工艺简单、可控且工艺重复性好等优势而成为目前最常用且唯一实现商用的GaN基增强型器件制备方法。首先，概述了当前制约P-GaN栅结构GaN基HEMT器件发展的首要问题，从器件结构与器件制备工艺这2个角度，综述了其性能优化举措方面的最新研究进展。然后，通过对研究进展的分析，总结了当前研究工作面临的挑战以及解决方法。最后，对未来的发展前景、发展方向进行了展望。     

AlGaN/GaN HEMTs表面钝化抑制电流崩塌的机理研究

通过实验测量对AlGaN/GaN HEMT表面钝化抑制电流崩塌的机理进行了深入研究.AlGaN/GaN HEMT Si3N4钝化层使用PECVD获得.文章综合考虑了钝化前后器件输出特性及泄漏电流的变化,钝化后直流电流崩塌明显减少,仍然存在小的崩塌是由于GaN缓冲层中的陷阱对电子的捕获.传输线模型测量表明,钝化后电流的增加是由于钝化消除了表面态密度进而增加了沟道载流子密度.     

基于AlGaN/GaN HEMT结构的ZnO纳米线感光栅极光电探测器

在传统的采用ZnO薄膜的AlGaN/GaN高电子迁移率晶体管(high electron mobility transistor, HEMT)光电探测器件中，存在光吸收、光电转换效率低，光电流小等诸多局限.为改善上述问题，基于AlGaN/GaN HEMT结构，提出并成功制备了一种ZnO纳米线感光栅极光电探测器.实验中首先通过水热法将ZnO纳米线成功制备到Si衬底材料及AlGaN/GaN HEMT衬底材料上，并利用X射线衍射(X-ray diffraction, XRD)仪、扫描电子显微镜(scanning electron microscope, SEM)、光致发光(photo luminescence, PL)光谱仪等仪器进行了一系列测试.结果表明，生长在AlGaN/GaN HEMT衬底材料上的ZnO纳米线具有更低的缺陷密度、更好的结晶度和更优异的光电特性.然后，将ZnO纳米线成功集成到AlGaN/GaN HEMT器件的栅极上，制备出具有ZnO纳米线感光栅极的AlGaN/GaN HEMT紫外光电探测器.将实验中制备出的具有ZnO纳米线感光栅极的AlGaN/GaN HEMT器件与常规的...     

感应耦合等离子体选择性刻蚀GaN／A1GaN

采用Cl2/Ar作为刻蚀气体．研究了在感应耦合等离子体干法刻蚀GaN、Al0.27，Ga0.73N材料中工艺参数对刻蚀速率及选择比的影响．GaN与Al0.27Ga0.72N之间的刻蚀选择比随自偏压的增大而减小．随感应耦合等离子体功率的增大变化不大．在Cl2／Ar为3：l的刻蚀气体中加入10％的O2对GaN刻蚀速率影响不大．却使Al0.27Ga0.73N刻蚀速率明显下降．从而提高了GaN与Al0.27Ga0.73N之间的刻蚀选择比．对比了采用不同自偏压刻蚀的Al0.27Ga0.73N材料肖特基的特性．发现反向漏电流随自偏压的增大而增大．     

2～6 GHz 100 W高效率平衡式功率放大器的研制

为解决传统宽带大功率放大器工作效率低的问题,采用新型电阻电抗连续B/J类功放模式拓展晶体管高效率的输出负载阻抗空间,从而提高宽带功放的漏级输出效率。提出了一款基于0.25μm栅长的氮化镓高电子迁移率晶体管（GaN HEMT）的平衡式功放。该功放将LC匹配网络和切比雪夫阻抗变换器相结合实现GaN HEMT器件宽带输入输出阻抗匹配,并利用3 dB Lange耦合器实现宽带平衡式功率合成。在连续波测试条件下,该平衡式功放在2～6 GHz频带内输出功率大于100 W,漏极效率大于45%,功率增益大于9.0 dB,抗负载失配比优于5:1。     

利用Ir(ppy)_3敏化CzHQZn提高OLED的性能

用CzHQZn作为受主,利用磷光敏化的方法制备了有机电致黄光和白光器件。黄光器件采用Ir(ppy)3掺杂4,4-N,N′-=咔唑基联苯(CBP),敏化新的黄光材料CzHQZn作为发光层,当发光层厚度为18nm时器件性能最好,最大发光效率为3.26cd/A(at10V),最大发光亮度为17560cd/m2(at10V);白光器件采用多发光层结构,结合ADN的蓝光复合发光,同时加入了电子阻挡层(NPBX)和空穴阻挡层(BCP),获得的白光器件最大发光效率为2.94cd/A(at8V),最大亮度为11089cd/m2(at13V)。     

500V沟槽阳极LIGBT的设计与优化

介绍一种双外延绝缘体上硅(silicon on insulator,SOI)结构的沟槽阳极横向绝缘栅双极型晶体管(trenchanode lateral insulated-gate bipolar transistor,TA-LIGBT).沟槽阳极结构使电流在N型薄外延区几乎均匀分布,并减小了元胞面积;双外延结构使漂移区耗尽层展宽,实现了薄外延层上高耐压低导通压降器件的设计.通过器件建模与仿真得到最佳TA-LIGBT的结构参数和模拟特性曲线,所设计器件击穿电压大于500 V,栅源电压Vgs=10 V时导通压降为0.2 V,特征导通电阻为123.6 mΩ.cm2.     

Impact of strain relaxation of AlGaN barrier layer on the performance of high Al-content AlGaN/GaN HEMT

Owing to large direct bandgap energy, high saturation drift velocity, large conduction band discontinuities, high thermal stability and strong piezoelectric and spontaneous po- larization[1-4], AlGaN/GaN HEMTs have advantages over electronic devices based on Si, GaAs and their alloys in high-frequency, -temperature and -power applications. Many researches show[5,6] that the characteristics of AlGaN/GaN HEMTs depend on two-dimensional gas (2DEG) in heterostructures which has intimate r…     

Study of GaN MOS-HEMT using ultrathin Al2O3 dielectric grown by atomic layer deposition

We report on a GaN metal-oxide-semiconductor high electron mobility transistor (MOS-HEMT) using atomic-layer deposited (ALD) Al₂O₃ as the gate dielectric. Through further decreasing the thickness of the gate oxide to 3.5 nm and optimizing the device fabrication process, a device with maximum transconductance of 150 mS/mm was produced. The drain current of this 0.8 μm gate-length MOS-HEMT could reach 800 mA/mm at +3.0 V gate bias. Compared to a conventional AlGaN/GaN HEMT of similar design, better interface property, lower leakage current, and smaller capacitance-voltage (C-V) hysteresis were obtained, and the superiority of this MOS-HEMT device structure with ALD Al₂O₃ gate dielectric was exhibited. Supported by the National Natural Science Foundation of China (Grant No. 60736033) and the National Basic Research Program of China (“973“) (Grant No. 51327020301)     

Development and characteristic analysis of enhancement-mode recessed-gate AlGaN/GaN HEMT

Fabrication of enhancement-mode high electron mobility transistors on AlGaN/GaN heterostructures grown on sapphire substrates is reported. These devices with 1 μm gate-length, 10 nm recessed-gate depth, 4 μm distance of source and drain exhibit a maximum drain current of 233 mA/mm at 1.5 V, a maximum transconductance of 210 mS/mm, and a threshold voltage of 0.12 V. The threshold voltage of these devices increased to 0.53 V after 500°C 5 min annealing in N₂ ambient. The saturation drain current and transconductance of 15 nm recessed-gate depth reduced compared to those of 10 nm recessed-gate depth, but the threshold voltage increased to 0.47 V. The relations between threshold voltage, controlling ability of gate and recess depth were validated by testing C-V structures on AlGaN/GaN heterostructures with different etching depth. Supported by the National Natural Science Foundation of China (Grant No. 60736033)     

新型VBO接口芯片静电放电防护器件

为了改进VBO接口电路静电放电（ESD）防护器件性能,提出2种新的ESD防护器件：栅二极管与面积效率二极管触发可控硅整流器（SCR）. 采用SMIC 40 nm CMOS工艺与SMIC 28 nm PS CMOS工艺制备传统二极管、栅二极管、面积效率SCR;通过半导体工艺及器件模拟工具（TCAD）进行仿真,分析电流密度;通过传输线脉冲测试（TLP）方法,测试不同结构ESD防护器件的Ⅰ-Ⅴ特性. 栅二极管的ESD鲁棒性为19.7 mA/μm,导通电阻为1.28 Ω,相较于传统二极管降低了38.8%. 面积效率二极管触发SCR触发电压为1.82 V,鲁棒性为48.1 mA/μm,相较于传统二极管提升了174.8%. 测试结果表明,栅二极管与ASCR和传统ESD器件相比,性能有极大的提升,适合用作VBO接口芯片的ESD防护.     

Bidirectional current path recessed gate tunnel field-effect transistor

The structure asymmetry of the conventional tunneling transistor makes it only able to have a unidirectional current path, which will cause the inconvenience of circuit design. In order to overcome this shortcoming, a novel recessed gate tunnel field-effect transistor with high performance is proposed in this paper and verified by silvaco TCAD software. The effects of process parameters such as doping concentration and geometry dimension on the energy band and properties of the device are analyzed. Simulation results show that the I_on／I_off ratio can reach 5×10⁶ at a 05V driving voltage and the minimum subthreshold swing of 12mV／dec at the 01V gate to source voltage. In general, this device has a large switching ratio and a very steep subthreshold slope under a low drive voltage. It is expected that this novel device can be one of the promising alternatives for ultra-low power applications.     

在高ECR 等离子体密度下沉积高质量氮化镓薄膜

目的　研究在电子回旋共振等离子体辅助法生长ＧａＮ 时的离子密度对其质量的影响．方法　用朗缪尔探针测量离子密度,用Ｘ 射线双晶衍射及霍尔测量分析ＧａＮ的质量与性能． 结果离子密度越高,薄膜的质量与性能就越好． 当生长ＧａＮ 时的离子密度为２－０ ×１０１１ ｃｍ － ３ 时,所得ＧａＮ 晶膜的氮镓量比接近于１ ,本底电子密度为３－７ ×１０１８ ｃｍ － ３ ,Ｘ 射线双晶衍射回摆曲线的半高宽为１６ ａｒｃｍｉｎ ． 结论　提高离子密度能明显提高ＧａＮ 的质量与性能     

AlGaN/GaN HEMT热形貌分布特性仿真

该文从泊松方程、连续性方程和晶格热方程出发,采用商用TCAD软件建立A1GaN/GaNHEMT器件二维模型.针对自加热效应,在不同的直流偏置电压下,对AlGaN/GaN HEMT器件进行了二维数值分析,获得相应的热形貌分布.     

具有场板结构GaN HEMT电场分布解析模型

基于具有场板结构GaN HEMT器件物理和基本器件方程,导出了器件加场板前后表面电场分布和峰值电场解析模型。当场板长度LFP与绝缘层厚度tox最优时,GaN HEMT栅极边缘电场峰值可降低至未加场板时的22%;若保持峰值电场恒定,则其漏端电压可由没有场板时的50 V提高到加场板后的225 V,增幅高出4倍。该解析模型所导出的电场分布与国外新近发表的源于器件方程和经验公式的模拟和实验结果基本吻合,为GaN HEMT器件场板设计提供了理论依据。