Characteristics and threshold voltage model of GaN-based FinFET with recessed gate

In this work, AlGaN/GaN FinFETs with different fin widths have been successfully fabricated, and the recessed-gate FinFETs are fabricated for comparison. The recessed-gate FinFETs exhibit higher transconductance value and positive shift of threshold voltage. Moreover, with the fin width of the recessed-gate FinFETs increasing, the variations of both threshold voltage and the transconductance increase. Next, transfer characteristics of the recessed-gate FinFETs with different fin widths and recessed-gate depths are simulated by Silvaco software. The relationship between the threshold voltage and the AlGaN layer thickness has been investigated. The simulation results indicate that the slope of threshold voltage variation reduces with the fin width decreasing. Finally, a simplified threshold voltage model for recessed-gate FinFET is established,which agrees with both the experimental results and simulation results.     

氧化镓材料与功率器件的研究进展

氧化镓(Ga₂O₃)以其禁带宽度大、击穿场强高、抗辐射能力强等优势,有望成为未来半导体电力电子领域的主力军。相比于目前常见的宽禁带半导体SiC和GaN,Ga₂O₃的Baliga品质因数更大、预期生长成本更低,在高压、大功率、高效率、小体积电子器件方面更具潜力。对Ga₂O₃外延材料、功率二极管和功率晶体管的国内外最新研究进行了概括总结,展望了Ga₂O₃在未来的应用与发展前景。     

基于神经网络的探地雷达探雷研究

根据对探地雷达回波信号的分析,提出了一种新的适合于现场处理的探雷方法,采用延时校正、维纳自适应滤波及减背景等手段对原始数据进行预处理,提取Welch功率谱密度估计作为目标的特征,将特征送入神经网络进行分类训练。使用地雷目标与共相近的物体的数据进行对比试验和神经网络测试,结果表明,经过训练的神经网络可有效地将地雷与其它干扰物分开。     

AlGaN/GaN双异质结F注入增强型高电子迁移率晶体管

理论模拟了不同GaN沟道厚度的双异质结(AlGaN/GaN/AlGaN/GaN)材料对高电子迁移率晶体管(HEMT)特性的影响,并模拟了不同F注入剂量下用该材料制作的增强型器件的特性差异.采用双异质结材料,结合F注入工艺成功地研制出了较高正向阈值电压的增强型HEMT器件.实验研究了三种GaN沟道厚度制作的增强型器件直流特性的差异,与模拟结果进行了对比验证.采用降低的F注入等离子体功率,减小了等离子体处理工艺对器件沟道迁移率的损伤,研制出的器件未经高温退火即实现了较高的跨导和饱和电流特性.对14 nm GaN沟道厚度的器件进行了阈值电压温度稳定性和栅泄漏电流的比较研究,并且分析了双异质结器件的漏致势垒降低效应.     

应用于X波段的0.2um V型栅槽AlGaN/GaN HEMT

研制出0.2um栅长 V型栅槽AlGaN/GaN HEMT。该0.2um栅槽是由0.6um 的光刻设计尺寸经过SiN各项同性淀积和各项异性刻蚀而形成。该0.2um栅长V型栅槽AlGaN/GaN HEMT最大截止频率为35GHz,最大震荡频率60GHz。在10GHz频率和20V漏偏压下,该器件最大输出功率达到4.44 W/mm ,功率附加效率49%。     

Photoresponse and trap characteristics of transparent AZO-gated AlGaN/GaN HEMT

AZO-gated and Ni/Au-gated AlGaN/GaN HEMTs are fabricated successfully,and an excellent transparency of AZOgated electrode is achieved.After a negative gate bias stress acts on two kinds of the devices,their photoresponse characteristics are investigated by using laser sources with different wavelengths.The effect of photoresponse on AZO-gated electrode device is more obvious than on Ni/Au-gated electrodes device.The electrons are trapped in the AlGaN barrier of AZO-gated HEMT after it has experienced negative gate bias stress,and then the electrons can be excited effectively after it has been illuminated by the light with certain wavelengths.Furthermore,the trap state density D_T and the time constantτ_T of the AZO-gated Schottky contact are extracted by fitting the measured parallel conductance in a frequency range from10 kHz to 10 MHz.The constants of the trap range from about 0.35 μs to 20.35 μs,and the trap state density increased from1.93×l0~(13)eV 1·cm~2 at an energy of 0.33 eV to 3.07×10~(11) eV~1·cm~2 at an energy of 0.40 eV.Moreover,the capacitance and conductance measurements are used to characterize the trapping effects under different illumination conditions in AZO-gated HEMTs.Reduced deep trap states' density is confirmed under the illumination of short wavelength light.     

Effects of the fluorine plasma treatment on low-density drain AlGaN/GaN HEMT

Low-density drain high-electron mobility transistors (LDD-HEMTs) with different F^- plasma treatment were investigated by simulations and experiments. The LDD region was performed by introducing negatively charged fluorine ions, which modified the surface field distribution on the drain side of the HEMT, and the enhancement of breakdown voltage were achieved. With the increased fluorine plasma treatment power and LDD region length, the breakdown voltage can be maximumly improved by 70%, and no severe reductions on output current and transconductance were observed. To confirm the temperature stability of the devices, annealing experiments were carried out at 400℃ for 2 min in ambient N₂. Moreover, the gate leakage current and breakdown voltage before and after annealing were compared and analyzed, respectively.     

F等离子体处理 AlGaN/GaN HEMT击穿电压和电流崩塌研究

F等离子体处理工艺被广泛的应用于 AlGaN/GaN HEMT增强型器件的研制和栅前处理工艺。本文研究了低功率F处理 AlGaN/GaN HEMT的击穿特性和电流崩塌特性。随着F处理时间的增加,饱和电流下降,阈值电压正向移动。对不同F处理时间的器件肖特基特性分析后发现,120s的F处理后器件栅泄漏电流明显减小,器件击穿电压提高,当F处理时间大于120s后,由于长时间F处理带来的损伤器件栅泄漏电流没有继续减小。采用不同偏置下的双脉冲测试对不同F处理时间的电流崩塌特性进行了研究,低功率F处理后没有发现明显的电流崩塌现象。     

核心机房电力电池区与设备区面积配比研究

动力系统是通信网络运行的能量源泉,是所有通信设备的能源供应者。随着移动通信网络的不断发展,主设备用电需求不断增加,导致核心机房电力电池室区域面积日益紧张。为了能更合理的利用机房面积,同时对未来新建机房大楼提出切实可行的电源区与设备区面积配比意见。本研究通过结合现网机房功率密度等数据、未来设备用电发展趋势,得出电源区与设备区面积配比结论。     

某国外大型IDC机房的电源系统建设方案分析

IDC机房的电源系统作为IDC机房最重要的基础设施之一,扮演着极其重要的角色。随着服务器机架功率及对电能质量要求的不断提升,如何优化配置UPS电源系统,如何降低UPS系统投资,如何提高整体UPS系统的效率有着非常现实的工程意义。以江苏省邮电规划设计院在海外承接的最大IDC项目为基础,文章研究分析和总结目前国际上较为先进的IDC机房配电方案,给未来中国的IDC机房设计和建设拓宽思路。