晶向对InGaP/GaAs HBT性能的影响

在对InGaP/GaAs HBT特性的研究中发现,发射极长边与主对准边垂直([011]方向)和平行([01 1]方向)放置时,其直流电流增益和截止频率是不同的.[011]方向的直流电流增益远远大于[01 1]方向,而它的截止频率则略小于[01 1]方向.文献中认为电流增益的不同是压电效应产生的,但这种观点并不能很好地解释截止频率的晶向依赖性.文中用压电效应和两个互相垂直方向上发射区侧向腐蚀形状的不同很好地解释了所有实验结果.     

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%     

新结构复合收集区InGaP/GaAs异质结双极晶体管结构设计及特性

利用电子运动速度过冲现象,设计出了一种新结构复合收集区In Ga P/Ga As异质结双极晶体管.这种结构不仅提高了器件的截止频率,而且降低了影响器件直流性能的补偿电压.所制备器件的截止频率达到77GHz,直流电流增益高达10 0 ,补偿电压低至70 m V .同时,把所制备器件的微波和直流特性与已发表的文献进行了比较,充分显示了这种结构的优越性.     

高功率密度自对准结构AlGaAs/GaAs异质结双极晶体管

利用各向异性的湿法刻蚀和侧墙隔离技术实现了发射极金属和基极金属的自对准 ,采用该自对准技术成功地研制出了自对准结构的 Al Ga As/ Ga As异质结双极晶体管 ,器件直流电流增益大于 2 0 ,电流增益截止频率 f T 大于30 GHz,最高振荡频率 fmax大于 5 0 GHz,连续波功率测量表明 :在 1d B增益压缩时 ,单指 HBT可以提供 10 0 m W输出功率 ,对应的功率密度为 6 .6 7W/ m m,功率饱和时最大输出功率 112 m W,对应功率密度为 7.48W/ m m,功率附加效率为 6 7%     

自对准AlGaAs/GaAs微波异质结双极晶体管(HBT)

本文提出了一种制作HBT采用的垂直台面结构自对准工艺.利用该工艺及对A1GaAs/GaAs具有高选择比的化学湿法腐蚀剂,已研制成微波HBT.发射区台面与基极电极间隙为0.1μm,最大直流电流增益为40,截止频率f_T为10GHz.     

微空气桥隔离的自对准AlGaAs/GaAs异质结双极晶体管

利用微空气桥隔离和自对准技术成功地研制出了自对准结构的AlGaAs/GaAs异质结双极晶体管.器件展现出良好的直流和高频特性.对于发射极面积为2μm×15μm的器件,直流电流增益大于10,失调电压(Offsetvoltage)200mV;电流增益截止频率f_T大于30GHz,最高振荡频率f_max约为50GHz.     

SiGe HBT直流电流增益模型研究

基于器件结构特点和电学特性,研究了影响SiGe HBT(异质结双极晶体管)直流电流增益的主要因素,分析了不同的电流密度条件下,器件的物理参数、结构参数与集电极电流密度和中性基区复合电流的关系,建立了SiGe HBT集电极电流密度,空穴反注入电流密度、中性基区复合电流、SRH(Shockley-Read- Hall)复合电流密度、俄歇复合电流密度以及直流电流增益模型,对直流电流增益模型进行了模拟仿真,分析了器件物理、结构参数以及复合电流与直流电流增益的关系,得到了SiGe HBT直流电流增益特性的优化理论依据.     

电光双折射控制GaAs垂直腔面发射激光的偏振

为将垂直腔面发射激光 (VCSEL)注入诸如磁光盘或相干探测系统之类的偏振敏感系统 ,VCSEL需有一优势偏振方向。大多数未经有意选择偏振方向的 VCSEL 在阈值或超阈值时显现正交偏振态 ,其不稳定偏振方向还随输入电流的增加而变化。尽管研究人员已利用各向异性横向腔体的方法发生单偏振占优的模式 ,甚至采用非 [0 0 1]砷化镓 (Ga As)作为衬底 ,但在装置制成后改变占优偏振模式仍不可能。韩国先进科技研究所和电子与通信研究所的研究人员与加州大学伯克利分校合作开发出一种基于 [0 0 1]砷化镓 (Ga As)衬底 ,利用电光双折射控VCSEL偏…     

蓝宝石衬底AlGaNöGaN 功率HEM Ts 研制

基于蓝宝石衬底的高微波特性 Al Ga N/Ga N HEMTs功率器件 ,器件采用了新的欧姆接触和新型空气桥方案。测试表明 ,器件电流密度 0 .784A/mm,跨导 1 97m S/mm,关态击穿电压 >80 V,截止态漏电很小 ,栅宽 1 mm的器件的单位截止频率 ( f T)达到 2 0 GHz,最大振荡频率 ( fmax) 2 8GHz,2 GHz脉冲测试下 ,栅宽 0 .75 mm器件 ,功率增益1 1 .8d B,输出功率 3 1 .2 d Bm,功率密度 1 .75 W/mm。     

新结构复合收集区InGaP/GaAs异质结双极晶体管结构设计及特性

利用电子运动速度过冲现象,设计出了一种新结构复合收集区InGaP/GaAs异质结双极晶体管.这种结构不仅提高了器件的截止频率,而且降低了影响器件直流性能的补偿电压.所制备器件的截止频率达到77GHz,直流电流增益高达100,补偿电压低至70mV.同时,把所制备器件的微波和直流特性与已发表的文献进行了比较,充分显示了这种结构的优越性.     

Self-aligned In0.49Ga0.51P/GaAs HBT DC and RF characteristics related with orientations

A self-aligned InGaP/GaAs HBT DC and RF characteristics related with orientations were studied. The DC current gain was greater for the [0 1 1] emitter orientation compared to orientation. However, it also showed slightly better RF performance for orientation with a cutoff frequency f_T 69 GHz compared to the f_T of 62 GHz for the [0 1 1] orientation. This experimental work has been proposed that the dependence of the characteristics could be attributed to both piezoelectric effect and the difference between lateral etched profiles in different directions.     

Orientation effect on AlGaAs/GaAs heterojunction bipolartransistors

Orientation effects on N-p-n AlGaAs/GaAs heterojunction bipolar transistors (HBT's) have been demonstrated for the first time. We have observed that the current gains of HBT's fabricated on the same wafer are strongly dependent on the emitter direction. The HBT's with emitter direction of [010] show the highest current gain and the smallest emitter-size effect. This orientation effect could be attributed to the piezoelectric effect, which superposes the piezoelectric charges to the original emitter doping and generates the weak lateral electric field that drifts the injected carriers at the emitter periphery. The difference of the saturation voltage between collector-emitter of those HBT's corresponds to the superposed piezoelectric charges     

射频薄膜体声波谐振器的研制和分析

研制了一种采用氮化硅/二氧化硅/氮化硅复合膜作为支持薄膜的高Q薄膜体声波谐振器.当采用单层氮化硅膜或二氧化硅膜作为谐振器的支持薄膜时,由于残余应力的作用,释放完的薄膜往往会出现褶皱的现象,极大地降低了薄膜体声波谐振器的Q值;上述复合膜结构有效地解决了这个问题.采用直流磁控溅射法制备了氧化锌压电薄膜,X射线衍射结果表明制备的氧化锌薄膜具有很好的c轴择优取向,意味着氧化锌薄膜具有较好的压电性.S参数测试结果表明该薄膜体声波谐振器在0.4～2.6GHz的频率范围内具有3个明显的谐振模式,计算了这些谐振模式的串联谐振频率、并联谐振频率、有效机电耦合系数和Q值.在这3个模式中,第3个谐波模式的工作频率约为2.4GHz,具有最高的Q值(约为500),可用来制备2.4GHz的低相噪射频振荡源.     

0.23 mu m gate length MODFETs on InAlAs/InGaAs/InP heterostructure grown by MOVPE

Modulation-doped field effect transistors (MODFETs) with 0.23 mu m gate lengths have been fabricated on an InAlAs/InGaAs/InP heterostructure grown by metal organic vapour phase epitaxy (MOVPE/MOCVD). Extrinsic DC transconductance as high as 800 mS/mm, and unity current gain cutoff frequency f/sub t/ of over 120 GHz at room temperature have been achieved. These g/sub m/ and f/sub t/ values compare favourably with the best devices of similar gate length grown by molecular-beam epitaxy (MBE) and are the highest values reported for any device grown by MOVPE.<>     

Al/sub 0.25/Ga/sub 0.75/As/In/sub 0.25/Ga/sub 0.75/As pseudomorphic MODFET with high DC and RF performance

AlGaAs/InGaAs MODFETs having 25% indium in the channel and L/sub G/=0.35 mu m have been fabricated. From DC device characterisation, a maximum saturation current of 670 mA/mm and an extrinsic transconductance of 500 mS/mm have been measured. A maximum unilateral gain cutoff frequency of f/sub c/=205 GHz and a maximum current gain cutoff frequency of f/sub T/=86 GHz have been achieved. Bias dependence of f/sub c/ and f/sub T/ has been measured. At 12 GHz a minimum noise figure of NF=0.8 dB and an associated gain of 11 dB have been measured.<>     

高频异质结晶体管直流和交流模型及其验证

针对漂移扩散方程和能量平衡方程的解建立了SiGe HBT的直流和交流理论模型,综合考虑了速度饱和效应、基区和发射区的禁带变窄效应和复合效应,并与台面型SiGe HBT实验结果进行了比较,截止频率为10.5 GHz,电流增益为45,与理论结果基本符合.     

GaInP/GaAs HBTs for high-speed integrated circuit applications

The use of GaInP/GaAs heterojunction bipolar transistors (HBTs) for integrated circuit applications is demonstrated. The discrete devices fabricated showed excellent DC characteristics with low V_ce offset voltage and very low temperature sensitivity of the current gain. For a non-self-aligned device with a 3-μm×1.4-μm emitter area, f_T was extrapolated to 45 GHz and f_max was extrapolated to 70 GHz. The measured 1/f noise level was 20 dB better than that of AlGaAs HBTs and comparable to that of low-noise silicon bipolar junction transistors, and the noise bump (Lorentzian component) was not observed. The fabricated gain block circuits showed 8.5 dB gain with a 3-dB bandwidth of 12 GHz, and static frequency dividers (divide by 4) were operable up to 8 GHz     

Enhanced microwave performance of ion-implanted MESFET with graded GaAs/AlGaAs heterojunctions

Ion-implanted MESFETs have been fabricated on an inverted GaAs/AlGaAs heterostructure. The aluminium concentration in the AlGaAs is graded from 0% at the substrate to 30% at the heterointerface. A maximum extrinsic transconductance of 410 mS/mm is achieved with 0.5 mu m gate devices. This heterojunction ion-implanted FET (HIFET) also exhibits enhanced microwave performance, especially at low drain current, when compared to conventional ion-implanted GaAs MESFETs. At 20% of I/sub dss/, the current gain cutoff frequency f/sub t/ is 40 GHz, which increases up to a maximum value of 47 GHz as the drain current rises. These characteristics of high f/sub t/ and high gain at low current are advantageous for low-noise applications.<>