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.     

非对称In0.53Ga0.47As/In0.52Al0.48As量子阱的零场自旋分裂能与高场g因子

我们研究了非对称In_0.53Ga_0.47As/In_0.52Al_0.48As量子阱中二维电子气的磁输运性质,所测量的样品的径向磁阻Rxx的Shubinikov-de Haas振荡没有呈现出拍频的特征。通过测量样品的弱局域效应提取了其零场自旋分裂能并通过对自旋分裂的Rxx双峰间距随倾斜角度theta的依赖关系的拟合提取了高场下的有效g因子。样品的Dingle plot图呈现非线性和特征,这可以归因于来自样品衬底附近的掺杂Be原子的长程势散射效应。     

Galvanomagnetic properties of two-dimensional electron gases in strain relaxed InxGa1−xAs(x<0.40) heterostructures grown by molecular beam epitaxy on GaAs substrates

We have investigated, as a function of indium content x, the galvanomagnetic and Shubnikov de Haas (SdH) properties of two-dimensional electron gases (2DEG) formed at lattice matched, strain relaxed InAlAs/InGaAs heterojunctions. These were grown by molecular beam epitaxy on GaAs misoriented substrates with a two degree offcut toward the nearest (110) plane. Variable temperature resistivity and Hall measurements indicate an increase in the electron sheet density n_s from 0.78×10¹²cm⁻² for x=0.15 to 1.80×10¹² cm⁻² for x=0.40 at 300K, and from 0.75×10¹²cm⁻² to 1.67×10¹²cm⁻² at T=1.6K. The room temperature electron mobility, measured along the in plane [110], direction is independent of indium content and equals approximately 9500 cm²/Vs. For T<50K, the mobility is independent of temperature decreasing with increasing x from 82000 cm²/Vs for x=0.15 to 33000 cm²/Vs for x=0.40. The ratios (τ_t/τ_q) at 1.6K between the electron relaxation time τ_t and the single particle relaxation time τq, for the strain relaxed specimens, as well as for pseudomorphically strained Al_0.35Ga_0.65As/In_0.15Ga_0.85As structures grown on GaAs substrates, and In_0.52Al_0.48As/In_0.53Ga_0.47As heterostructures grown lattice matched on InP substrates. Such a study indicates the presence of inhomogeneities in the 2DEGs of the strain relaxed specimens which appear to be related to the process of strain relaxation. Such inhomogeneities, however, have little effect on the electron relaxation time τ_t which, at low temperatures, is limited principally by alloy scattering.     

功率增益截止频率为183GHz的In0.53Ga0.47As/In0.52Al0.48As HEMTs

通过合理的外延层材料结构设计和改进的器件制备工艺,制备出功率增益截止频率(fmax)为183GHz的晶格匹配InP基In0.53Ga0.47As-In0.52Al0.48As HEMT.该fmax为国内HEMT器件最高值.还报道了器件的结构、制备工艺以及器件的直流和高频特性.     

截止频率为218GHz的超高速晶格匹配In0.53Ga0.47As/In0.52Al0.48As高电子迁移率晶体管

报道了截止频率为218GHz的晶格匹配的In0.53Ga0.47As/In0.52Al0.48As高电子迁移率晶体管.这是迄今为止国内报道的截止频率最高的高电子迁移率晶体管.器件直流特性也很优异:跨导为980mS/mm,最大电流密度为870mA/mm.文中的材料结构和所有器件制备工艺均为本研究小组自主研制开发.     

InGaAs(InAlAs)/InP和InP/InAlAs湿法选择腐蚀研究

介绍了两种选择腐蚀液对InGaAs(InAlAs)I/nP和InPI/nAlAs异质结构材料选择腐蚀的实验结果,重点介绍在InAlAs上面生长InP的湿法选择腐蚀,用HClH∶3PO4C∶H3COOH系列腐蚀液,InPI/nAlAs选择比大于300。InPI/nAlAs湿法选择腐蚀的结果可以很好应用到OEIC芯片制作中,并取得了较好的器件及电路结果。     

掺杂InGaAs／InAlAs单量子阱中电子对称态和反对称态磁输运研究

利用变温Hall测量研究了重掺杂InGaAs／InAlAs单量子阱中二维电子气，发现在量子阱中由于存在电子对称态和反对称态导致纵向电阻出现拍频现象。通过分析拍频节点位置，得到电子对称态和反对称态之间的能级间距为4meV。此外，通过迁移率谱方法和多载流子拟合过程研究了不同迁移率电子的浓度和迁移率随温度的变化关系。     

单电源供电MSM/HEMT OEIC

给出了InGaAsMSM光探测器与InP基InAlAs/InGaAs HEMT两种器件单片集成实现的OEIC光接收机的设计方法与测试结果。该光接收机采用单电源供电，由一级放大器，两级源级跟随器和一个反馈电阻组成，当光接收机工作在2．5Gbit/s时，跨阻可达53dBΩ，采用＋5V电源供电，功耗仅为160mW，可有效地应用在光纤通信接收系统中。     

0.25μm GaAs基MHEMT器件

采用普通接触曝光研制成栅长为0 .2 5 μm的Ga As基In Al As/ In Ga As变组分高电子迁移率晶体管(MHEMT) ,测得其跨导为5 2 2 m S/ m m,沟道电流密度达4 90 m A/ mm,截止频率为75 GHz,比同样工艺条件下Ga As基In Ga P/ In Ga As PHEMT的性能有很大的提高.对该器件工艺及结果进行了分析,提取了器件的交流小信号等效电路模型参数,并提出了进一步得到高稳定性、高性能器件的方法.     

Subnanometer Analysis and Modeling of MBE Grown InP Based MODFETs

InGaAs/InAlAs double-doped double-strained modulation-doped field-effect transistors OD-SMODFETs)1 were grown by solid source molecular beam epitaxy. The structures were characterized using high resolution x-ray diffraction, Hall effect, and cross-sectional scanning tunneling microscopy. A record two-dimensional electron gas (2DEG) sheet density of 8.5 × 10¹²/cm² and 8.1 × 10¹²/cm² for 300 and 77K, respectively, was achieved. The mobility was 6500 and 12000 cm²/ Vs for 300 and 77K, respectively. To the author’s knowledge,² the previous record 2DEG result was 6.58 × 10¹²/cm². The electron mobility was limited by alloy scattering and interface roughness caused by the presence of “clustering.” Using cross-sectional scanning tunneling microscopy to verify the presence of these clusters, we have the first images of the lattice matched InAlAs (spacer)-InGaAs (quantum well) interface. These images reveal clusters that have approximate spherical or cylindrical shapes with equivalent cubic dimensions ranging from 25 to 45Å.