RF-MBE生长的AlGaN/GaN高电子迁移率晶体管特性

用射频分子束外延技术研制出了室温迁移率为10 35 cm2 /(V·s) ,二维电子气浓度为1.0×10 1 3cm- 2 ,77K迁移率为2 6 5 3cm2 /(V·s) ,二维电子气浓度为9.6×10 1 2 cm- 2 的Al Ga N/Ga N高电子迁移率晶体管材料.用此材料研制的器件(栅长为1μm,栅宽为80μm,源-漏间距为4μm )的室温非本征跨导为186 m S/m m,最大漏极饱和电流密度为92 5 m A/m m,特征频率为18.8GHz.     

一种新的HEMT小信号模型参数提取方法

介绍了一种高电子迁移率晶体管(HEMT)的小信号参数提取方法——综合多偏置点优化参数提取法。该文首先推导并提出了器件的模型、确定外部参数和内部参数，其次介绍了多偏置点优化算法。最后，以PHEMT器件为例进行鲁棒性和精确性测试，实验采用一系列随机起始值，结果表明，提取的参数值与经验值相差小于1％。     

Thermal stability of interfaces between metals and InP-based materials

The thermal stability of interfaces between metals (Ni, Pt, Ti, Mo) and III-V compound semiconductors has been investigated by the application of Rutherford backscattering spectrometry. Metal diffusion and interfacial lattice disorder of the semiconductors were analyzed for various metal/semiconductor samples annealed at temperatures up to 500°C. The interfaces of Ni/GaAs and Ti/GaAs were found to be more stable than those of Ni/In-based semiconductors and Ti/ In-based semiconductors, respectively. Faster diffusion of Pt atoms was ob-served in In-and As-containing materials than in P-containing materials. Mo/ semiconductor interfaces were the most stable.     

RF-MBE生长的AlGaN/GaN高电子迁移率晶体管特性

用射频分子束外延技术研制出了室温迁移率为1035cm2/(V·s),二维电子气浓度为1.0×1013cm-2,77K迁移率为2653cm2/(V·s),二维电子气浓度为9.6×1012cm-2的AlGaN/GaN高电子迁移率晶体管材料.用此材料研制的器件(栅长为1μm,栅宽为80μm,源-漏间距为4μm)的室温非本征跨导为186mS/mm,最大漏极饱和电流密度为925mA/mm,特征频率为18.8GHz.     

Genetic algorithm‐based neural‐network modeling approach applied to AlGaN/GaN devices

An accurate equivalent circuit large‐signal model (ECLSM) for AlGaN‐GaN high electron mobility transistor (HEMT) is presented. The model is derived from a distributed small‐signal model that efficiently describes the physics of the device. A genetic neural‐network‐based model for the gate and drain currents and charges is presented along with its parameters extraction procedure. This model is embedded in the ECLSM, which is then implemented in CAD software and validated by pulsed and continuous large‐signal measurements of on‐wafer 8 × 125‐μm GaN on SiC substrate HEMT. Pulsed IV simulations show that the model can efficiently describe the bias dependency of trapping and self‐heating effects. Single‐ and two‐tone simulation results show that the model can accurately predict the output power and its harmonics and the associated intermodulation distortion (IMD) under different input‐power and bias conditions. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

Analysis of issues in gate recess etching in the InAlAs/InGaAs HEMT manufacturing process

We have developed an InAlAs/InGaAs metamorphic high electron mobility transistor device fabrication process where the gate length can be tuned within the range of 0.13 μm–0.16 μm to suit the intended application. The core processes are a two-step electron-beam lithography process using a three-layer resist and gate recess etching process using citric acid. An electron-beam lithography process was developed to fabricate a T-shaped gate electrode with a fine gate foot and a relatively large gate head. This was realized through the use of three-layered resist and two-step electron beam exposure and development. Citric acid-based gate recess etching is a wet etching, so it is very important to secure etching uniformity and process reproducibility. The device layout was designed by considering the electrochemical reaction involved in recess etching, and a reproducible gate recess etching process was developed by finding optimized etching conditions. Using the developed gate electrode process technology, we were able to successfully manufacture various monolithic microwave integrated circuits, including low noise amplifiers that can be used in the 28 GHz to 94 GHz frequency range.     

小型化L波段1 000 W GaN内匹配功率管研制

L波段功率单管有增大功率的需求,但会面临体积较大的问题。基于0.5μm工艺研发了GaN高电子迁移率晶体管(HEMT)管芯,单芯功率达到300 W。通过负载牵引仿真提取模型的输入、输出最佳阻抗点。用高介电常数薄膜电路设计L-C网络,拉高芯片的输入输出阻抗,并抵消虚部。用微带电路设计两级阻抗变换的宽带功率分配器及合路器电路,进行四胞管芯合成。内置稳定电路、栅极和漏极供电偏置电路,实现高度集成化、小型化,以及50Ω输入输出阻抗匹配。芯片总栅宽4×40 mm,在漏压50 V、脉宽40μs、占空比4%的测试条件下,在0.96 GHz到1.225 GHz的宽带频段内,输出功率为60 dBm到61.2 dBm,效率为57.9%到72%,饱和功率增益大于14 dB。     

High‐efficiency transmission‐line inverse Class F power amplifiers for 2‐GHz WCDMA systems

In this article, a novel load‐network solution to implement the transmission‐line inverse Class F power amplifiers for base station WCDMA applications is presented. The theoretical analysis is based on an analytical derivation of the optimum load‐network parameters to control the second and third harmonics at the device output, including the device output parasitic shunt capacitance and series inductance. The transmission‐line inverse Class F LDMOSFET and GaN HEMT power amplifiers using NXP BLF6G22LS‐75 and CREE CGH27060F devices, respectively, were designed and measured. The high‐performance results with the drain efficiency of 70.2% and power gain of 18.0 dB for a 60‐W LDMOSFET power amplifier and with the drain efficiency of 82.3% and power gain of 14.3 dB for a 50‐W GaN HEMT power amplifier were achieved at an operating frequency of 2.14 GHz. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

C波段GaN HEMT功率放大器设计

该文介绍了一款应用于38 GHz的大功率超宽带功率放大器。电路设计中采用了键合线连接裸片与微带电路,并对该部分单独进行电磁场仿真。采用渐变微带线的方法实现了宽带匹配,通过HFSS与ADS的联合仿真优化设计,完成了大功率宽频带的功率放大器设计和仿真过程,仿真结果表明在频率38 GHz范围内增益（8．5＆#177;1） dB,1 dB压缩点输出功率为48 dBm最大饱和功率为49．5 dBm。     

Traps centers and deep defects contribution in current instabilities for AlGaN/GaN HEMT's on silicon and sapphire substrates

AlGaN/GaN high electron mobility transistors (HEMTs) with Si and Al₂O₃ substrates reveals anomalies on I_ds-V_ds-T and I_gs-V_gs-T characteristics (degradation in drain current, kink effect, barrier height fluctuations, etc.). Stress and random telegraph signal (RTS) measurements prove the presence of trap centers responsible for drain current degradation. An explanation of the trapping mechanism responsible for current instabilities is proposed. Deep defects analysis performed by capacitance transient spectroscopy (C-DLTS), frequency dispersion of the output conductance (G_ds(f)), respectively, on gate/source and drain/source contacts and RTS prove the presence of deep defects localized, respectively, in the gate and in the channel regions. Defects detected by C-DLTS and G_ds(f) are strongly correlated, respectively, to barrier height inhomogeneities and kink anomalies. Gate current analysis confirms the presence of (G-R) centers acting like traps at the interface GaN/AlGaN. Finally, the localization of these traps defects is proposed.