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对不同掺杂浓度AlGaN/GaN HEMTs施加直流偏置应力,研究掺杂AlGaN/GaN HEMTs电流崩塌效应.实验表明,掺杂AlGaN势垒层对器件电流崩塌效应有明显的抑制作用,随着掺杂浓度增加,掺杂对电流崩塌效应的抑制作用越显著.这是因为对于掺杂AlGaN/GaN HEMT,表面态俘获电子将耗尽掺杂AlGaN层,从而能对2DEG起屏蔽作用.AlGaN体内杂质电离后留下正电荷也能进一步屏蔽表面态对沟道2DEG的影响. 相似文献
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针对传统AlGaN/GaN HFET击穿电压远低于理论值,以及阈值电压与开态电流之间存在制约关系的问题,提出一种对称极化掺杂增强型高压GaN HFET。采用Al组分对称渐变的AlGaN势垒层,因极化梯度分别在正向渐变AlGaN层和逆向渐变AlGaN层中诱导产生了三维电子气(3DEG)和三维空穴气(3DHG)。利用3DHG,阻断了源极与3DEG之间的纵向导通沟道,实现了新的增强型模式。同时,正向渐变AlGaN层的高浓度3DEG显著提升了器件输出电流。器件关断时,极化电荷形成的极化结有助于耗尽漂移区,优化了电场分布,提升了器件耐压。与传统AlGaN/GaN HFET相比,新器件的击穿电压从39 V提高至919 V,饱和漏电流提升了103.5%。 相似文献
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电流崩塌效应是限制AlGaN/GaN HFET高输出功率特性的一个重要因素,文中从器件研制的角度研究了AlGaN/GaN HFET的电流崩塌效应.研究结果表明,采用传统的化合物半导体器件细栅工艺制作的器件,栅边缘易发生钻蚀效应,SiN层出现钻蚀区域,器件电流崩塌明显;采用ICP刻蚀SiN后,AlGaN表面产生损伤,电流崩塌效应进一步增强;采用电子束直写方式和SiN钝化,电子未对AlGaN层产生损伤,电流崩塌参量小于20%;采用场板结构,SiN层增加了表面态俘获电子的释放通道.电流崩塌效应得到进一步抑制,减小到小于10%. 相似文献
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AlGaN/GaN HFET的2DEG和电流崩塌研究(Ⅱ) 总被引:1,自引:0,他引:1
4 AlGaN/GaN HFET电流崩塌的机理 电流崩塌(图8)是AlGaN/CaN HFET存在的特殊问题也是能否走向实用化的关键问题.图中,Ⅰdsmo和Ⅰdsmf、Vko和Vkf分别代表直流和射频条件下的源漏饱和电流和饱和(膝)电压. 相似文献
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基于静电学分析,得出表面态是电子的一个重要来源.基于这一分析,可以解释已发表的关于二维电子气(2DEC)的大量数据.例如,2DEG密度随着AlGaN层厚度、Al组分的变化的原因.当A10.3Ga0.7N/GaN结构中生长一层5 nm厚的GaN冒层时,2DEG浓度由1.47×1013cm-2减少到1.20×1013cm-2,减少是由于表面类施主态离化减少.由于充分厚的GaN冒层导致GaN/AlGaN/GaN上界面形成二维空穴气(2DHG),所以在超出特定的冒层厚度时2DEG浓度达到饱和. 相似文献
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比较有无AlN插入层AlGaN/GaN HEMTs在直流偏置应力条件下的电流崩塌程度,研究AlN插入层对电流崩塌的影响.从测试结果看,无AlN插入层的AlGaN/GaN HEMTs有更显著的电流崩塌程度,表明AlN插入层对电流崩塌效应有显著的抑制作用.模拟的AlGaN/GaN能带结构表明,AlN插入层能显著提高AlGaN导带底能级,增加异质结的带隙差.带隙差的增加有利于减小电子遂穿几率,加强沟道二维电子气的量子限制,从而抑制电流崩塌效应. 相似文献
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介绍了国际上AlInN势垒HFET的最新发展.从器件性能分析中发现这种新势垒显著提高了沟道电子气密度,增大了强场漂移速度,消除应变提高了器件可靠性和热稳定性,能在高温下有效工作,使GaN HFET研究走上新的台阶.但是薄势垒引起的大栅流和电流崩塌是阻碍器件性能提高和实际应用的主要瓶颈.利用AlInN/AlGaN异质界面... 相似文献
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AlGaN/GaN界面特性研究进展 总被引:2,自引:0,他引:2
GaN是一种宽禁带半导体材料,由于具有优越的热稳定性和化学稳定性,使这种材料和与其相关的器件可以工作在高温和恶劣的环境中,并可用于大功率微波器件。本文主要介绍AlGaN/GaN有关界面特性,该特性反映了纵向纳米尺度下的能带特性;从AlGaN/GaNHEMT设计出发,给出了材料性质和结构参数对AlGaN/GaN异质结二维电子气特性影响的研究结果;讨论了AlGaN/GaN界面2DEG载流子的输运性质;分析了材料缺陷对AlGaN/GaN界面2DEG性质的影响;指出了有待研究的问题和方向。 相似文献
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A new surface-potential-based model for AlGaN/AlN/GaN high electron mobility transistor(HEMT) is proposed in this paper. Since the high polarization effects caused by AlN interlayer favorably influence the two dimensional electron gas(2DEG) and scattering mechanisms, we first add spontaneous and piezoelectric charge terms to the source equation of surface-potential, and a mobility model for AlGaN/AlN/GaN HEMT is rewritten. Compared with TCAD simulations, the DC characteristics of AlGaN/AlN/GaN HEMT are faithfully reproduced by the new model. 相似文献
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The influence of annealed ohmic contact metals on the electron mobility of a two dimensional electron gas (2DEG) is investigated on ungated AlGaN/GaN heterostructures and AlGaN/GaN heterostructure field effect transistors (AlGaN/GaN HFETs). Current-voltage (I-V) characteristics for ungated AlGaN/GaN heterostructures and capacitance-voltage (C-V) characteristics for AlGaN/GaN HFETs are obtained, and the electron mobility for the ungated AlGaN/GaN heterostructure is calculated. It is found that the electron mobility of the 2DEG for the ungated AlGaN/GaN heterostructure is decreased by more than 50% compared with the electron mobility of Hall measurements. We propose that defects are introduced into the AlGaN barrier layer and the strain of the AlGaN barrier layer is changed during the annealing process of the source and drain, causing the decrease in the electron mobility. 相似文献
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基于Sentaurus Workbench(SWB)TCAD可制造性设计平台进行AlGaN/GaN器件的结构设计和仿真,并对影响二维电子气的重要参数因素进行了研究及优化,诸如AlGaN势垒层中Al组分x、AlGaN势垒层厚度h、应变弛豫度r和栅偏压Vg等因素。参数相关性的制约结果,无疑会反映在对器件物理特性的制约及影响上。研究结果表明,在一定条件下增大势垒层中Al组分和势垒层厚度可以提高器件的电流传输特性。然而随着二者的不断增大将会引起应变弛豫的发生,而应变弛豫的发生会降低器件的性能。 相似文献
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Tuning Electrical and Thermal Transport in AlGaN/GaN Heterostructures via Buffer Layer Engineering
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Ananth Saran Yalamarthy Hongyun So Miguel Muñoz Rojo Ateeq J. Suria Xiaoqing Xu Eric Pop Debbie G. Senesky 《Advanced functional materials》2018,28(22)
Progress in wide bandgap, III–V material systems based on gallium nitride (GaN) has enabled the realization of high‐power and high‐frequency electronics. Since the highly conductive, 2D electron gas (2DEG) at the aluminum gallium nitride (AlGaN)/GaN interface is based on built‐in polarization fields and is confined to nanoscale thicknesses, its charge carriers exhibit much higher mobilities compared to their doped counterparts. This study shows that such 2DEGs also offer the unique ability to manipulate electrical transport separately from thermal transport, through the examination of fully suspended AlGaN/GaN diaphragms of varied GaN buffer layer thickness. Notably, ≈100 nm thin GaN layers can considerably impede heat flow without electrical transport degradation. These achieve 4× improvement in the thermoelectric figure of merit (zT) over externally doped GaN, with state‐of‐the‐art power factors of 4–7 mW m‐1 K‐2. The remarkable tuning behavior and thermoelectric enhancement, elucidated here for the first time in a polarization‐based heterostructure, are achieved because electrons are at the heterostructured interface, while phonons are within the material system. These results highlight the potential for using 2DEGs in III–V materials for on‐chip thermal sensing and energy harvesting. 相似文献
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Investigation of Self-Heating Effects in Submicrometer GaN/AlGaN HEMTs Using an Electrothermal Monte Carlo Method 总被引:1,自引:0,他引:1
Toufik Sadi Robert W. Kelsall Neil J. Pilgrim 《Electron Devices, IEEE Transactions on》2006,53(12):2892-2900
An electrothermal Monte Carlo (MC) method is applied in this paper to investigate electron transport in submicrometer wurtzite GaN/AlGaN high-electron mobility transistors (HEMTs) grown on various substrate materials including SiC, Si, GaN, and sapphire. The simulation method is an iterative technique that alternately runs an MC electronic simulation and solves the heat diffusion equation using an analytical thermal resistance matrix method. Results demonstrate how the extent of the thermal droop in the Id-Vds characteristics and the device peak temperature depend upon both the biasing conditions and the substrate material type. Polarization effects are considered in the simulations, as they greatly influence electron transport in GaN/AlGaN HEMTs by creating a highly concentrated two-dimensional electron gas (2DEG) at the GaN/AlGaN interface. It is shown that a higher 2DEG density provides the devices with a better current handling capability but also increases the importance of the thermal effects 相似文献
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An analytical charge control model considering the insulator/AlGaN interface charge and undepleted Al-GaN barrier layer is presented for AlGaN/GaN metal-insulator-semiconductor heterostructure field effect transistors (MIS-HFETs) over the entire operation range of gate voltage. The whole process of charge control is analyzed in detail and partitioned into four regions: Ⅰ-full depletion, Ⅱ-partial depletion, Ⅲ-neutral region and Ⅳ-electron accu-mulation at the insulator/AlGaN interface. The results show that two-dimensional electron gas (2DEG) saturates at the boundary of region Ⅱ/Ⅲ and the gate voltage should not exceed the 2DEG saturation voltage in order to keep the channel in control. In addition, the span of region Ⅱaccounts for about 50% of the range of gate voltage before 2DEG saturates. The good agreement of the calculated transfer characteristic with the measured data confirms the validity of the proposed model. 相似文献
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G.A. Umana-Membreno T.B. FehlbergS. Kolluri D.F. BrownG. Parish B.D. NenerS. Keller U.K. MishraL. Faraone 《Microelectronic Engineering》2011,88(7):1079-1082
In this work, we present results of a study of anisotropic two-dimensional electron gas (2DEG) transport in N-polar GaN/AlGaN heterostructures grown on slightly mis-oriented sapphire substrates. High-resolution mobility spectrum analysis of magnetic-field dependent Hall-effect and resistivity indicate an isotropic 2DEG sheet carrier density, yet significant anisotropy was observed in carrier mobility. A single electron species with a narrow mobility distribution was found to be responsible for conduction parallel to the multi-atomic steps resulting from growth on the vicinal substrates; whilst in the perpendicular direction two distinct electrons peaks are evident at T ? 150 K, which merge near room temperature. The linewidth of the mobility distributions for transport in the perpendicular direction was found to be significantly broader than that of the single electron in the parallel direction. The broader mobility distribution and the lower average mobility for the 2DEG in the perpendicular direction are attributable to interface roughness scattering associated with the GaN/AlGaN interfacial steps. 相似文献