Ka波段AlGaN/GaN HEMT栅结构仿真研究

为了研究适合Ka波段AlGaN/GaN HEMT的栅结构尺寸,借助二维器件仿真软件Silvaco Atlas,在完善仿真模型的基础上研究了Γ型栅各部分对AlGaN/GaN HEMT特性的影响,包括栅长与短沟道效应的关系、栅与沟道距离对短沟道效应和饱和漏电流的影响,以及栅金属厚度对fmax,栅场板对fT、fmax和内部电场的影响。根据典型器件结构和材料参数的仿真表明,为了提高频率并减轻短沟道效应,栅长应取0.15～0.25μm;减小栅与沟道的距离可略微改善短沟道效应,但会明显降低器件的饱和漏电流,综合考虑栅调制能力、饱和漏电流、短沟道效应三个方面,栅与沟道距离应取10～20nm;为了提高fmax,栅金属厚度应大于0.4μm;缩小栅场板长度可有效提高器件的频率,兼顾Ka波段应用和提高击穿电压,栅场板长度应在0.3～0.4μm左右。仿真得出的器件性能随结构参数的变化趋势以及尺寸数据对于Ka波段AlGaN/GaN HEMT的研究具有参考意义。     

AlGaN/GaN HEMT器件的研制

介绍了AlGaN/GaNHEMT器件的研制及室温下器件特性的测试.漏源欧姆接触采用Ti/Al/Pt/Au ,肖特基结金属为Pt/Au .器件栅长为1μm ,获得的最大跨导为12 0mS/mm ,最大的漏源饱和电流密度为0 95A/mm .     

Optimized power simulation of AlGaN/GaN HEMT for continuous wave and pulse applications

An optimized modeling method of 8 × 100 μm AlGaN/GaN-based high electron mobility transistor (HEMT) for accurate continuous wave (CW) and pulsed power simulations is proposed. Since the self-heating effect can occur during the continuous operation, the power gain from the continuous operation significantly decreases when compared to a pulsed power operation. This paper extracts power performances of different device models from different quiescent biases of pulsed current-voltage (I-V) measurements and compared them in order to determine the most suitable device model for CW and pulse RF microwave power amplifier design. The simulated output power and gain results of the models at V_gs = -3.5 V, V_ds = 30 V with a frequency of 9.6 GHz are presented.     

基于AlGaN/GaN HEMT的X波段内匹配功率合成放大器的设计

利用内匹配和功率合成技术设计了X波段AlGaN/GaN HEMT功率合成放大器.电路包含有四个AlGaN/GaN HEMT和制作在Al2O3陶瓷基片上的输入输出匹配电路.在偏置条件VDS=30 V,IDS=700 mA时8 GHz测出连续波饱和输出功率达到Pat=40 dBm(10 W),最大PAE=37.44%,线性增益9 dB.     

AlGaN/GaN HEMT器件的高温特性

研究了AlGaN/GaNHEMT器件在室温、100℃、200℃和300℃下的工作性能。当栅长为1μm时,器件的最大漏源电流和非本征跨导在室温下的数值为1.02A/mm和230mS/mm。温度升高到100℃时几乎没有变化,温度升高到300℃时,最大漏源电流和跨导分别下降到0.69A/mm和118.25mS/mm,下降的百分比分别为:67.6%和51.4%。     

14.2 W/mm internally-matched AlGaN/GaN HEMT for X-band applications

High-performance X-band AlGaN/GaN high electron mobility transistor (HEMT) has been achieved by Γ-gate process in combination with source-connected field plate. Both its Schottky breakdown voltage and pinch-off breakdown voltage are higher than 100 V. Beside, excellent superimposition of direct current (DC) I-V characteristics in different V_ds sweep range indicates that our GaN HEMT device is almost current collapse free. As a result, both outstanding breakdown characteristics and reduction of current collapse effect guarantee high microwave power performances. Based upon it, we have developed an internally-matched GaN HEMT amplifier with single chip of 2.5 mm gate periphery, which exhibits power density of 14.2 W/mm with 45.5 dBm (35.5 W) output power and a power added efficiency (PAE) of 48% under V_ds = 48 V pulse operating condition at 8 GHz. To the best of our knowledge, it is the highest power density at this power level.     

AlGaN/GaN HEMT小信号模型参数提取算法

本文采用了新型的22元件AlGaN/GaN HEMT小信号等效电路模型,较传统的模型,增加了栅漏电导Ggdf和栅源电导Ggsf来表征GaN HEMT的栅极泄漏电流。同时针对新型的栅场板、源场板结构器件,提出了一种改进的寄生电容参数提取方法,使之适用于提取非对称器件的小信号模型参数。为验证此模型,获得了S参数的测试结果和模型仿真结果,此二者的吻合度较高,表明新型的22元件小信号模型精确、稳定而且物理意义明确。     

蓝宝石衬底上槽栅型X波段增强型AlGaN/GaN HEMT

研制了一款X波段增强型AlGaN/GaN高电子迁移率晶体管(HEMT)。在3英寸(1英寸=2.54 cm)蓝宝石衬底上采用低损伤栅凹槽刻蚀技术制备了栅长为0.3μm的增强型AlGaN/GaN HEMT。所制备的增强型器件的阈值电压为0.42 V,最大跨导为401 mS/mm,导通电阻为2.7Ω·mm。器件的电流增益截止频率和最高振荡频率分别为36.1和65.2 GHz。在10 GHz下进行微波测试,增强型AlGaN/GaN HEMT的最大输出功率密度达到5.76 W/mm,最大功率附加效率为49.1%。在同一材料上制备的耗尽型器件最大输出功率密度和最大功率附加效率分别为6.16 W/mm和50.2%。增强型器件的射频特性可与在同一晶圆上制备的耗尽型器件相比拟。     

AlGaN/GaN HEMT二维静态模型与模拟

考虑AlGaN/GaN材料的自发、压电极化效应和量子效应,通过泊松方程、薛定谔方程和流体力学方程组的数值自洽求解方法,对AlGaN/GaN HEMT的二维静态模型与模拟问题进行了研究,得到了器件区域的导带图、二维电子气分布、电子温度特性、直流输出和转移特性,并对模拟结果进行了分析与讨论.     

Two-Dimensional Static Numerical Modeling and Simulation of AlGaN/GaN HEMT

考虑AlGaN/GaN材料的自发、压电极化效应和量子效应,通过泊松方程、薛定谔方程和流体力学方程组的数值自洽求解方法,对AlGaN/GaN HEMT的二维静态模型与模拟问题进行了研究,得到了器件区域的导带图、二维电子气分布、电子温度特性、直流输出和转移特性,并对模拟结果进行了分析与讨论.     

非掺杂AlGaN/GaN HEMT微波功率器件

介绍了非掺杂GaN HEMT微波功率器件的结构、制造工艺和测试结果. 制作了几种0.6μm栅长、100～1000μm不同栅宽的器件，对于栅宽分别为100, 300和500μm的器件，典型最大跨导为190～170mS/mm；截止频率比较相近，大约为24GHz；而最高振荡频率随栅宽增加而降低，分别为56, 46和40GHz. 测试了8GHz频率时，不同工作条件下1000μm栅宽器件的连续波微波功率特性：Vds=17V, Id=310mA, Pin=25.19dBm时，Po=30dBm (1W) ,Ga=4.81dB; Vds=18V, Id=290mA, Pin=27dBm时，Po=31.35dBm (1.37W) ,Ga=4.35dB.     

跨导为220mS/mm的AlGaN/GaN HEMT

介绍了 Al Ga N/ Ga N HEMT器件的研制及室温下器件特性的测试。漏源欧姆接触采用 Ti/ Al/ Pt/ Au,肖特基结金属为 Pt/ Au。器件栅长为 1 μm,获得最大跨导 2 2 0 m S/ mm,最大的漏源饱和电流密度 0 .72 A/ mm。由 S参数测量推出器件的截止频率和最高振荡频率分别为 1 2 GHz和 2 4GHz。     

AlGaN/GaN材料HEMT器件优化分析与I-V特性

在考虑Al Ga N / Ga N异质结中的压电极化和自发极化效应的基础上,自洽求解了垂直于沟道方向的薛定谔方程和泊松方程.通过模拟计算,研究了Al Ga N / Ga N HEMT器件掺杂层Al的组分、厚度、施主掺杂浓度以及栅偏压对二维电子气特性的影响.用准二维物理模型计算了Al Ga N/ Ga N HEMT器件的输出特性,给出了相应的饱和电压和阈值电压,并对计算结果和Al Ga N/ Ga N HEMT器件的结构优化进行了分析.     

AlGaN/GaN HEMT栅阶跃脉冲响应实验研究

通过对AlGaN/GaN HEMT漏极电流栅阶跃脉冲响应实验测试,发现栅脉冲相同时,HEMT开启时间在线性区随VDS增加而增加,而在饱和区随VDS增加而减小;在VDS一定时,器件开启时间随栅脉冲低电平的降低而增加。基于表面态电子释放过程与ID、VDS和阶跃脉冲之间关系的分析,提出了用快电子与慢电子释放两种过程来解释表面态电子弛豫,并建立漏极电流响应过程拟合算式。拟合得到与快、慢电子释放相关的时间常数分别为τ1=0.23s、τ2=1.38s,且拟合曲线与实验结果的最大误差不超过测试值的3%。该研究结果有助于电流崩塌机理的进一步探索。     

Hydrogen sensors based on AlGaN/AlN/GaN HEMT

Pt/AlGaN/AlN/GaN high electron mobility transistors (HEMT) were fabricated and characterized for hydrogen sensing. Pt and Ti/Al/Ni/Au metals were evaporated to form the Schottky contact and the ohmic contact, respectively. The sensors can be operated in either the field effect transistor (FET) mode or the Schottky diode mode. Current changes and time dependence of the sensors under the FET and diode modes were compared. When the sensor was operated in the FET mode, the sensor can have larger current change of 8 mA, but its sensitivity is only about 0.2. In the diode mode, the current change was very small under the reverse bias but it increased greatly and gradually saturated at 0.8 mA under the forward bias. The sensor had much higher sensitivity when operated in the diode mode than in the FET mode. The oxygen in the air could accelerate the desorption of the hydrogen and the recovery of the sensor.     

应用于大功率MMIC开关的AlGaN背势垒GaN HEMT

报道了应用于大功率开关的AlGaN背势垒0.25μm GaN HEMT。通过引入AlGaN背势垒,MOCVD淀积在3英寸SiC衬底上的AlGaN/GaN异质结材料缓冲层的击穿电压获得了大幅度的提升,相比于普通GaN缓冲层和掺Fe GaN缓冲层击穿电压提升幅度分别为4倍和2倍。采用具有AlGaN背势垒AlGaN/GaN 外延材料研制的GaN HEMT开关管在源漏间距为2μm、2.5μm、3μm、3.5μm和4μm时,估算得到的关态功率承受能力分别为25.0W、46.2W、64.0W、79.2W和88.4W。基于源漏间距为2.5μm的GaN HEMT开关管设计了DC-12GHz的单刀双掷MMIC开关。该开关采用了反射式串-并-并结构,整个带内插入损耗最大1.0dB、隔离度最小30dB,10GHz下连续波测试得到其功率承受能力达44.1dBm。     

A high-performance enhancement-mode AlGaN/GaN HEMT

An enhancement-mode AlGaN/GaN HEMT with a threshold voltage of 0.35 V was fabricated by fluorine plasma treatment.The enhancement-mode device demonstrates high-performance DC characteristics with a saturation current density of 667 mA/mm at a gate bias of 4 V and a peak transconductance of 201 mS/mm at a gate bias of 0.8 V.The current-gain cut-off frequency and the maximum oscillation frequency of the enhancement-mode device with a gate length of μm are 10.3 GHz and 12.5 GHz,respectively,which is comparable with the depletion-mode device.A numerical simulation supported by SIMS results was employed to give a reasonable explanation that the fluorine ions act as an acceptor trap center in the barrier layer.     

一种新的AlGaN/GaN HEMT半经验直流特性模型

在EEHEMT1模型的基础上给出一种新的A1GaN/GaN HEMT半经验直流特性模型,考虑了栅源电压对膝点电压的影响,得到描述AlGaN/GaN HEMT器件I-Ⅴ特性的方程.此模型可以应用于蓝宝石和SiC两种不同衬底AlGaN/GaN HEMT器件的I-Ⅴ特性模拟.仿真结果和实验测量结果拟合误差小于3%.     

高性能的增强型AlGaN/GaN HEMT

采用氟离子处理的方法实现了阈值电压0.35V的增强型AlGaN/GaN HEMT 器件。该器件展示了高性能直流特性,最大饱和电流 667mA/mm,器件的峰值跨导达到203ms/mm。 1μm栅长电流增益截止频率和最大振荡截止频率分别为10.3GHz和12.5GHz,并且小信号特性在器件氟离子处理后并没有出现衰退。最后,采用SIMS的实验结果辅助进行了数值仿真,对氟离子在势垒层中起受主缺陷的理论给出了合理的解释。     

一种新的AlGaN/GaN HEMT半经验直流特性模型

在EEHEMT1模型的基础上给出一种新的A1GaN/GaN HEMT半经验直流特性模型,考虑了栅源电压对膝点电压的影响,得到描述AlGaN/GaN HEMT器件I-Ⅴ特性的方程.此模型可以应用于蓝宝石和SiC两种不同衬底AlGaN/GaN HEMT器件的I-Ⅴ特性模拟.仿真结果和实验测量结果拟合误差小于3%.