Detection of lead ions with AlGaAs/InGaAs pseudomorphic high electron mobility transistor

Lead poisoning is a serious environmental concern, which is a health threat. Existing technologies always have some drawbacks, which restrict their application ranges, such as real time monitoring. To solve this problem, glutathione was functionalized on the Au-coated gate area of the pseudomorphic high electron mobility transistor (pHEMT) to detect trace amounts of Pb²⁺. The positive charge of lead ions will cause a positive potential on the Au gate of the pHEMT sensor, which will increase the current between the source and the drain. The response range for Pb²⁺ detection has been determined in the concentrations from 0.1 pmol/L to 10 pmol/L. To our knowledge, this is currently the best result for detecting lead ions.     

AlGaAs／InGaAs功率PHEMT用异质材料的计算机优化与器件实验结果

借助一新的工艺模拟与异质器件模型用ＣＡＤ软件──ＰＯＳＥＳ（Ｐｏｉｓｓｏｎ－ＳｃｈｒｏｅｄｉｎｇｅｒＥｑｕａｔｉｏｎＳｏｌｖｅｒ），对以ＡｌＧａＡｓ／ＩｎＧａＡｓ异质结为基础的多种功率ＰＨＥＭＴ异质层结构系统（传统、单层与双层平面掺杂）进行了模拟与比较，确定出优化的双平面掺杂ＡｌＧａＡｓ／ＩｎＧａＡｓ功率ＰＨＥＭＴ异质结构参数，并结合器件几何结构参数的设定进行器件直流与微波特性的计算，用于指导材料生长与器件制造。采用常规的ＨＥＭＴ工艺进行ＡｌＧａＡｓ／ＩｎＧａＡｓ功率ＰＨＥＭＴ的实验研制。对栅长０．８μｍ、总栅宽１．６ｍｍ单胞器件的初步测试结果为：ＩＤｓｓ２５０～４５０ｍＡ／ｍｍ；ｇｍ０２５０～３２０ｍＳ／ｍｍ；Ｖｐ－２．０－２．５Ｖ；ＢＶＤＳ５～１２Ｖ。７ＧＨｚ下可获得最大１．６２Ｗ（功率密度１．０Ｗ／ｍｍ）的功率输出；最大功率附加效率（ＰＡＥ）达４７％。     

InGaAs/AlGaAs量子阱中量子尺寸效应对PL谱的影响

本文采用金属有机物化学气相淀积(MOCVD)方法设计并生长了两组InGaAs／A1GaAs应变多量子阱，量子阱的厚度分别为3nm和6nm，对其光致发光谱(PL)进行了研究，二者的发光波长分别为843nm和942nm，用有限深单量子阱理论近似计算了由于量子尺寸效应和应变效应引起的InGaAs／A1GaAs量子阱带隙的改变，这解释了两组样品室温下PL发射波长变化的原因。     

Current-voltage behavior of AlGaAs/InGaAs pHEMT structures and the effect of optical illumination

Various pseudomorphic High Electron Mobility Transistor (pHEMT) structures of AlGaAs/InGaAs alloys have been observed their current-voltage behavior. The tungsten probes were used for a measurement the structures by ramping the voltage from −5 to 5 V and measure the electrical current. Measurement was carried out at room temperature and also under optical illumination. From the measurement, the electrical current was found to increase as the increase of Al content in the AlGaAs alloys layer in the pHEMT structure. This phenomenon was supported by the decrease of sheet resistance as obtained from Hall effect measurement. Under visible light illumination, the current-voltage behavior of pHEMT structure was observed to vary as the light power density was varied for 0, 25 and 55 μW/cm.     

Effects of hot-electron stress on electrical performances in AlGaAs/InGaAs pseudomorphic high electron transistors

The effects of hot-electron stress on electrical properties in AlGaAs/InGaAs pseudomorphic high electron mobility transistors were investigated using current-voltage (I–V), capacitance-voltage (C-V), deep level transient spectroscopy (DLTS), and transconductance dispersion measurements. After hot-electron stress, the three-terminal gate-drain breakdown characteristics were improved and the gate-drain capacitance was decreased even though no difference was found in both DLTS and transconductance dispersion results. These results suggest that hot electrons were trapped at the interface of the passivation layer, Si₃N₄, with AlGaAs, locating between gate and source/drain electrodes, leading to the increase of the depletion region under the ungated region. On the other hand, the two-terminal gate-drain breakdown characteristics were deteriorated by hot-electron stress. This was due to the reduction of the Schottky barrier height.     

增强型InGaP/AlGaAs/InGaAs PHEMT小信号等效电路参数的提取

介绍了增强型InGaP／AlGaAs／InGaAs PHEMT小信号等效电路中元件参数值的提取方法，并利用IC-CAP软件EEHEMT1模型提取了参数．利用ADS软件验证了提参结果，ADS仿真的直流I-V曲线和S参数与实测结果基本吻合．结果表明EEHEMT1模型可以用于提取增强型PHEMT参数，并且具有可操作性．     

增强型InGaP/AlGaAs/InGaAs PHEMT小信号等效电路参数的提取

介绍了增强型InGaP/AlGaAs/InGaAs PHEMT小信号等效电路中元件参数值的提取方法,并利用IC-CAP软件EEHEMT1模型提取了参数.利用ADS软件验证了提参结果,ADS仿真的直流I-V曲线和S参数与实测结果基本吻合.结果表明EEHEMT1模型可以用于提取增强型PHEMT参数,并且具有可操作性.     

Power improvement of AlGaAs/InGaAs PHEMTs by using low gamma radiation dose

This paper shows the possibility to improve DC and RF electrical performances of AlGaAs/InGaAs PHEMTs by using low gamma radiation dose. The drain-source saturation current and the DC transconductance increase when the devices are irradiated with a gamma dose of 42.8 krad(GaAs) and then remain constant up to 0.85 Mrad(GaAs). This improvement is attributed to a reduction of access resistances. In the same time, the Schottky diode and the current-gain cut-off frequency of these components are not degraded by the gamma irradiation. Moreover, the maximum output power density is improved by 18%. This paper demonstrates that it is possible to improve the component electrical performances by using an original method.     

结构函数法评估漏源电压对AlGaAs/InGaAs PHEMTs热阻的影响

本文通过实验测量和仿真研究了不同漏源电压对AlGaAs/InGaAs PHEMTs热阻的影响。结果表明,等功率下,热阻随着漏源电压的减小呈下降趋势,并且小电压大电流下热阻值最小。应用结构函数法可以分别提取出芯片级和封装级的热阻值。模拟结果表明,沟道中电场最强的地方出现在靠近漏一侧的栅边缘,相对较小的漏源电压产生的电场也较低,这就是导致等功率下热阻随漏源电压下降的原因。     

As元素分子态对InGaAs/AlGaAs量子阱红外探测器性能的影响

对As2和As4两种不同分子态下利用分子束外延技术(MBE)生长的单层AlGaAs薄膜和GaAs基InGaAs/AlGaAs量子阱红外探测器(QWIP)的性能进行了研究,发现As2条件下生长的单层AlGaAs材料荧光强度更大、深能级缺陷密度更低;相对于As4较为复杂的吸附、生长机制引入的缺陷,在As2条件下生长的InGaAs/AlGaAs QWIP具有更低的暗电流密度、更好的黑体响应、更高的比探测率和更优异的器件均匀性。生长制备的InGaAs/AlGaAs QWIP在60K的工作温度、-2V偏压下,暗电流密度低至7.8nA/cm2,光谱响应峰值波长为3.59μm,4V偏压下峰值探测率达到1.7×1011 cm·Hz1/2·W-1。另外,通过As元素的不同分子态下InGaAs/AlGaAs QWIP光响应谱峰位的移动可以推断出As元素的不同分子态也会影响In的并入速率。     

Ka波段AlGaAs/InGaAs低噪声PHEMT异质材料结构的计算机优化与实验结果

讨论了毫米波低噪声ＰＨＥＭＴ的设计要点，藕助Ｓｃｈｒｏｅｄｉｎｇｅｒ／Ｐｏｉｓｓｏｎ方程及器件方程，进行了Ｋａ波段ＡｌＧａ／ＩｎＧａＡｓ低噪声ＰＨＥＭＴ用异质层数值计算及ＣＡＤ优化，确定出分子束外延ＭＢＥ时诸层的最佳组分、浓度、与厚度、上述优化分析的结果用于器件的实验研制，取得了３４．４ＧＨｚ下噪声系数（ＮＦ）１．９２ｄＢ、相关增益Ｇａ６．５ｄＢ的国内最好结果。     

基于循环退火技术的InGaAs/AlGaAs量子阱混杂

为了解决由于激光器腔面处的光吸收引起的腔面光学灾变损伤(COD),采用无杂质空位扩散(IFVD)法,研究了由SiO2电介质层诱导的InGaAs/AlGaAs量子阱结构的带隙蓝移。使用等离子化学气相沉积(PECVD)在InGaAs/AlGaAs量子阱的表面生长SiO2电介质层;然后采用IFVD在N2环境下进行高温退火实验,从而实现量子阱混杂(QWI)。实验结果表明:蓝移量的大小随退火时间和电介质层厚度的变化而变化,样品覆盖的电介质层越厚,在相同的退火温度下承受的退火时间越长,得到的蓝移量也越大。然而,在高温退火中的时间相对较长时,退火对量子阱造成的损坏相当大。高温短时循环退火,能够在保护量子阱晶体质量的同时实现QWI。通过在850℃退火6min下循环退火5次,得到了46nm的PL蓝移,且PL峰值保持在原样品的80%以上。     

A revised ideal model for AlGaAs/GaAs quantum well solar cells

Quantum well solar cells (QWSCs) are heterostructure devices intended to achieve higher efficiencies than conventional cells. This paper extends a previous model for QWSC current-voltage characteristics by revising the equations for the absorbed flux and by introducing expressions to calculate radiative recombination coefficients and well effective densities-of-states. This revised model is in agreement with previous experimental results for AlGaAs/GaAs. Since the revised model incorporates detailed balance calculations, its predictions are consistent with the efficiency restrictions of this theory. The revised model, however, does predict efficiency enhancements for QWSCs in some configurations if non-radiative recombination is dominant, even in such a poor QWSC material as AlGaAs/GaAs.     

S波段0.3W AlGaAs/GaAsHBT功率管

采用标准的湿法刻蚀工艺研制出了 S波段工作的非自对准 Al Ga As/ Ga As异质结双极晶体管 .对于总面积为 8× 2 μm× 10 μm的 HBT器件 ,测得其直流电流增益大于 10 ,电流增益截止频率 f T 大于 2 0 GHz,最高振荡频率fmax大于 30 GHz.连续波功率输出为 0 .3W,峰值功率附加效率 41%     

大应变InGaAs/GaAs/AlGaAs微带超晶格中波红外QWIP的MOCVD生长

基于中波红外(峰值响应波长4.5μm)量子阱红外探测器QWIP进行了大应变In0.34Ga0.66As/GaAs/Al0.35Ga0.65As微带超晶格结构的MOCVD外延生长研究。通过对生长温度、生长速率、Ⅴ/Ⅲ比以及界面生长中断时间等生长参数的系统优化,获得了高质量的外延材料。     

InAlAs/InGaAs/InP基PHEMTs小信号建模及低噪声应用

利用改进的小信号模型对采用100nmInAlAs/InGaAs/InP工艺设计实现的PHEMTs器件进行建模, 并设计实现了一款W波段单片低噪声放大器进行信号模型的验证。为了进一步改善信号模型低频S参数拟合差的精度, 该小信号模型考虑了栅源和栅漏二极管微分电阻, 在等效电路拓扑中分别用Rfs和Rfd表示.为了验证模型的可行性, 基于该信号模型研制了W波段低噪声放大器单片.在片测试结果表明:最大小信号增益为14.4dB@92.5GHz, 3dB带宽为25GHz@85-110GHz.而且, 该放大器也表现出了良好的噪声特性, 在88GHz处噪声系数为4.1dB, 相关增益为13.8dB.与同频段其他芯片相比, 该放大器单片具有宽3dB带宽和高的单级增益.     

Relaxation study of AlGaAs cladding layers in InGaAs/GaAs (111)B lasers designed for 1.0-1.1 μm operation

InGaAs/GaAs-based lasers require thick AlGaAs cladding layers to provide optical confinement. Although the lattice mismatch between GaAs and AlGaAs is very low, relaxation may occur due to the thickness requirement for an AlGaAs waveguide of the order of microns. We have studied the relaxation of InGaAs/GaAs lasers with AlGaAs waveguides grown on GaAs (111)B substrates. We have observed by transmission electron microscopy (TEM) that certain AlGaAs layers show a high density of threading dislocations (TDs), whilst other AlGaAs layers remain essentially dislocation free. To explain the experimental results a model based on dislocation multiplication has been developed. TDs in the AlGaAs cladding layers are observed when the critical layer thickness (CLT) for dislocation multiplication has been overcome. Consequently, a design rule based on a modified CLT model for AlGaAs/GaAs (111)B is proposed.     

Power performance and scalability study of AlGaAs/GaAs double-recessed pseudomorphic high electron mobility transistors on unthinned substrate for coplanar waveguide circuit applications

We have investigated the power performance and scalability of AlGaAs/GaAs Double-Recessed Pseudomorphic High Electron Mobility Transistors (DR-PHEMTs) at 10 GHz on an unthinned GaAs substrate for CoPlanar Waveguide (CPW) circuit applications. It was found that the output power varied linearly with the logarithm of the device’s gate width ranging from 200 to 1000 μm. It increased at a rate of 0.01 dB/μm. That worked out to a doubling of output power (or 3 dB) for every 300 μm increase in the gate width. Gain decreased at a rate of about 0.005 dB/μm while PAE generally improved when the gate width was increased. As for DC measurement, the maximum transconductance of the device was about 375 mS/mm at V_G = −0.5 V and V_DS = 3 V. The gate-drain breakdown voltage (BV_GD) measured was −20 V, defined at I_G = −1 mA/mm. The microwave performance of the devices was measured on-wafer using a load-pull system at a bias of V_G = −0.5 V and V_DS = 8 V. For a device with a gate width of 1 mm, its saturated CW output power, gain and PAE value at 10 GHz was 27.5 dBm (0.55 W), 8 dB and 48%, respectively. At this same set of bias conditions, the value of f_t and f_max was 40 and 80 GHz, respectively.     

Modelling and simulation of low-frequency broadband LNA using InGaAs/InAlAs structures: A new approach

The ultra-low leakage properties of a novel InGaAs/InAlAs/InP structure have been used to fabricate large gate periphery pHEMTs (up to 1200 μm²) required for wide band low-noise amplifiers (LNA). The devices were characterized and both linear and non-linear models were extracted. LNAs were then designed and compared favourably with the best results reported to date between 0.3 and 2 GHz, still using a 1 μm gate length optical lithography.     

用于高速量子密码系统的1.25 GHz InGaAs/InP单光子探测器的研制

随着量子密码领域的快速发展,近红外单光子探测器的研究已经成为该领域的研究重点和技术制高点。报道了一种基于正弦门控与滤波技术的InGaAs/InP雪崩光电二极管(APD)高速单光子探测器,门控频率达到1.25GHz。在探测效率为10.3%时,暗计数概率为1.3×10-6/gate,后脉冲概率为5.6×10-5/ns。这种高速单光子探测器将大幅度提升量子密码系统的两个关键指标——密钥率和传输距离,为下一代高速量子密码系统的实用化应用奠定了基础。