用MOMBE生长掺碳或掺锡的npn和pnp AlGaAs/GaAs HBT

<正>npn GaAs/AlGaAs HBT是一种具有优良特性的器件,在数字、模拟及微波等方面均具有广阔的应用前景。pnp GaAs/AlGaAs HBT在互补技术应用方面也是一种很重要的器件。 《Electronics Letters》1991年12月发表了介绍制造npn和pnp GaAs/AlGaAs HBT的文章。近期实验表明,在HBT制造中用掺碳和锡代替掺铍和硅能减少寄生电阻与提高可靠性,且具有很好的直流和射频特性。     

一种新型结构的InGaP/GaAs负阻异质结晶体管

利用硅双基区晶体管（DUBAT）产生负阻的原理,针对HBT器件结构和MBE材料结构的特点,设计并研制出一种基区刻断结构的负阻型HBT (NDRHBT) . 经过特性和参数测试,证明此种NDRHBT具有显著的微分负阻效应,并发现负电流区负阻效应和光照可改变其I-V特性,器件模拟结果和测试结果基本一致.     

一种新型结构的InGaP/GaAs负阻异质结晶体管

利用硅双基区晶体管(DUBAT)产生负阻的原理,针对HBT器件结构和MBE材料结构的特点,设计并研制出一种基区刻断结构的负阻型HBT(NDRHBT).经过特性和参数测试,证明此种NDRHBT具有显著的微分负阻效应,并发现负电流区负阻效应和光照可改变其I-V特性,器件模拟结果和测试结果基本一致.     

基于MEMS技术新型硅磁敏三极管负阻-振荡特性

介绍了-种新型硅磁电负阻-振荡器件--S型负阻-振荡硅磁敏三极管.该器件是基于MEMS技术在p型高阻单晶硅片上制作的具有立体结构的新型磁电转换器件,采用KOH各向异性腐蚀技术实现发射区及引线的制作.实验结果表明,集电极电流随外加磁场的变化而变化;在基极注入电流一定时,出现集电极电流受外加偏压VCE调制的负阻-振荡特性,且集电极电流振荡随外加磁场而变化.对该器件负阻-振荡特性的形成机理进行了讨论,结果表明,在集电区n+π结和基区与π区形成的p+π结均处于反偏条件下,当π区满足雪崩倍增效应产生的条件时,该磁敏三极管伏-安特性曲线中的Vp+x偏压相对应的基极注入条件下的集电极电流出现S型负阻-振荡特性.在发射极和基极间的n+π结和p+π结附近存在的大量深能级杂质将对负阻-振荡特性进行调制.     

基于1.5 μm BiCMOS 工艺的SiGe HBT器件设计优化

基于非选择性外延,自对准注入技术,集电区选择性注入和快速热退火工艺,提出了一种适用于1.5μm BiCMOS集成技术的SiGe HBT器件结构。该结构具有内基区薄,外基区厚,B/E结两侧杂质浓度低,发射极/基极自对准诸优点。利用TSuprem4和Medici进行工艺模拟和电学特性仿真。结果表明,所设计的的SiGe HBT具有良好的电学特性,其最大电流增益为210,当Vce=2.5 V时,截止频率达到65 GHz,验证了器件结构设计的合理性。     

AlGaAs/GaAs超薄基区负阻HBT的研制与模拟

利用化学湿法选择技术和监控电极技术设计并研制了一种新型台面结构超薄基区AlGaAs/GaAs负阻异质结双极晶体管,该器件具有独特且显著的电压控制型负阻特性,其峰谷比可高于120.通过器件模拟分析,解释了该器件产生负阻的原因,即不断增加的集电极电压致使超薄基区穿通,器件由双极管工作状态向体势垒管工作状态转化造成的.另外,模拟结果表明器件可能具有较高频率特性(fT约为60～80GHz).     

AlGaAs/GaAs超薄基区负阻HBT的研制与模拟

利用化学湿法选择技术和监控电极技术设计并研制了一种新型台面结构超薄基区AlGaAs/GaAs负阻异质结双极晶体管,该器件具有独特且显著的电压控制型负阻特性,其峰谷比可高于120.通过器件模拟分析,解释了该器件产生负阻的原因,即不断增加的集电极电压致使超薄基区穿通,器件由双极管工作状态向体势垒管工作状态转化造成的.另外,模拟结果表明器件可能具有较高频率特性(fT约为60～80GHz).     

基于MEMS技术新型硅磁敏三极管负阻-振荡特性

介绍了一种新型硅磁电负阻振荡器件——S型负阻-振荡硅磁敏三极管．该器件是基于MEMS技术在p型高阻单晶硅片上制作的具有立体结构的新型磁电转换器件，采用KOH各向异性腐蚀技术实现发射区及引线的制作．实验结果表明，集电极电流随外加磁场的变化而变化；在基极注入电流一定时，出现集电极电流受外加偏压VCE调制的负阻-振荡特性，且集电极电流振荡随外加磁场而变化．对该器件负阻振荡特性的形成机理进行了讨论，结果表明，在集电区n+π结和基区与π区形成的p+π结均处于反偏条件下，当π区满足雪崩倍增效应产生的条件时，该磁敏三极管伏-安特性曲线中的Vp+π偏压相对应的基极注入条件下的集电极电流出现S型负阻-振荡特性．在发射极和基极间的n+π结和p+π结附近存在的大量深能级杂质将对负阻-振荡特性进行调制．     

超高压SiGe HBT器件结构及制作工艺研究

介绍了一种超高压锗硅异质结双极晶体管(SiGe HBT)的器件结构及制作工艺。该器件增大了N型赝埋层到有源区的距离,采用厚帽层锗硅基区及低浓度发射区的制作工艺,以提高SiGe HBT的击穿电压;在基区和发射区之间利用快速热处理提高工艺稳定性,并使HBT的电流增益(β)恢复到原来水平,以弥补厚帽层锗硅基区及低发射区浓度造成的电流增益降低。基区断开时,发射区到集电区的击穿电压(BVCEO)提高至10V,晶体管特征频率达到20GHz。     

HBT自热效应对功率放大器偏置电路的影响及补偿

研究了GaAs HBT的自热效应对功率放大器镜像电流源偏置电路性能的影响.HBT自热效应使得这种偏置电路的镜像精度和温度特性变差.利用HBT器件特有的集电极电流热电负反馈理论,通过优化基极偏置电阻的方法,对自热效应进行了有效补偿,偏置电路的电流镜像精度得到有效提高,偏置电流温度漂移由9.5%减小到0.5%.     

Fabrication and Simulation of an AlGaAs/GaAs Ultra-Thin Base NDR HBT

A novel mesa ultra-thin base AlGaAs/GaAs HBT is designed and fabricated with wet chemical selective etch technique and monitor electrode technique.It has a particular and obvious voltage-controlled NDR whose PVCR is larger than 120.By use of device simulation,the cause of NDR is that increasing collector voltage makes the ultra-thin base reach through and the device transforms from a bipolar state to a bulk barrier state.In addition,the simulated cutoff frequency is about 60～80GHz.     

Theoretical and experimental characterization of the DUal-BAse transistor (DUBAT)

A new A-type integrated voltage controlled differential negative resistance device using an extra effective base region to form a lateral pnp (npn) bipolar transistor beside the original base region of a vertical npn (pnp) bipolar junction transistor, and so called the DUal BAse Transistor (DUBAT), is studied both experimentally and theoretically, The DUBAT has three terminals and is fully comparible with the existing bipolar integrated circuits technologies. Based upon the equivalent circuit of the DUBAT, a simple first-order analytical theory is developed, and important device parameters, such as: the I–V characteristic, the differential negative resistance, and the peak and valley points, are also characterized. One of the proposed integrated structures of the DUBAT, which is similar in structure to I²L but with similar high density and a normally operated vertical npn transistor, has been successfully fabricated and studied. Comparisons between the experimental data and theoretical analyses are made, and show in satisfactory agreements.     

负阻异质结晶体管的模拟与实验

采用MBE方法生长了8nm基区的InGaP/GaAs双异质结材料,研制成具有负阻特性的异质结晶体管.在恒压恒流条件下均观察到了负阻特性并对其物理机制进行了讨论.推导出集电极电流Ic与VCE的关系表达式,讨论了负阻与器件结构和参数的关系.使用PSPICE模拟软件建立电路网表模型,代入推导出的IC-VCE公式进行模拟,模拟结果与器件的测量结果十分接近.     

Simulation of npn and pnp AlGaN/GaN heterojunction bipolartransistors performances: limiting factors and optimum design

The performance capabilities of npn and pnp AlGaN/GaN heterojunction bipolar transistors have been investigated by using a drift-diffusion transport model. Numerical results have been employed to study the effect of the p-type Mg doping and its incomplete ionization on device performance. The high base resistance induced by the deep acceptor level is found to be one of the causes of limited current gain values for npn devices. Reasonable improvements of the dc current gain β are observed by realistically reducing the base thickness and consequently the transit time, in accordance with processing limitations. Base transport enhancement is predicted by the introduction of a quasi-electric field in the base. The impact of the base resistivity on high-frequency characteristics is investigated for npn AlGaN/GaN devices. Simulation results reveal the difficulty to achieve decent current gain values at high current density for pnp HBTs in common emitter configuration. Despite the high electron mobility in the n-type base that aids in reducing the base resistance, a preliminary analysis for pnp devices indicates limited rf performances caused by the reduced minority hole transport across the base     

用离子注入和掩埋金属自对准技术改善Si/SiGe HBT性能

在器件纵向结构确定后,常规工艺制作的SiGe／SiHBT噪声性能不理想的主要原因是其基极电阻较大,高频性能不理想主要是由于其基极和发射极台面面积较大造成的;为达到改善其高频与低噪声性能的目的,在不改变光刻工艺精度的情况下,采用离子注入和掩埋金属自对准工艺方法完成了器件制作;与传统制作方法相比,前者可减小外基区电阻,后者可以减小电极接触电阻,并能使器件的台面面积做得更小。在此基础上,我们测试了器件的最小噪声系数与最高截止频率,结果表明：用自对准工艺制作的器件的高频噪声与频率性能都显著改善。     

基区设计对InGaP/GaAs HBT热稳定性的影响

研究了不同基区设计对多发射极指结构功率InGaP/GaAs异质结双极型晶体管热稳定性的影响。以发生电流增益崩塌的临界功率密度为热稳定性判定标准,推导了热电反馈系数Φ、集电极电流理想因子η和热阻Rth与基区掺杂浓度NB、基区厚度dB的理论公式。基于TCAD虚拟实验,观测了不同基区掺杂浓度和不同基区厚度分别对InGaP/GaAs HBT热稳定性的影响。结合理论公式,对仿真实验曲线进行了分析。结果表明,基区设计参数对热稳定性有明显的影响,其影响规律不是单调变化的。通过基区外延层参数的优化设计,可以改进多指HBT器件的热稳定性,从而为多指InGaP/GaAs HBT热稳定性设计提供了一个新的途径。     

与HBT工艺兼容的新型负阻器件的研制与分析

在HBT工艺基础上,通过对器件结构的特殊设计,研制出了一类新型三端负阻器件,其恒压控制型负阻的PVCR大于800,并伴有恒流控制型负阻。通过atlas器件模拟软件进行模拟后对其物理机制进行了解释。该器件既能保持HBT高频、高速的特点,又具有负阻、双稳、自锁等特性,同时与普通台面HBT工艺兼容,易于集成,是一种具有研究和应用价值的新型负阻器件。     

Integrated npn/pnp GaAs/AlGaAs HBTs grown by selective MBE

npn and pnp GaAs/AlGaAs heterojunction bipolar transistors have been successfully fabricated on the same GaAs substrate using selective molecular beam epitaxy and a new merged HBT processing technology. The DC and microwave characteristics of the transistors are equivalent to those of similar HBTs grown by conventional MBE on separate GaAs substrates.<>     

Low frequency noise in complementary npn and pnp polysilicon emitter bipolar junction transistors

Low frequency noise characteristics of high voltage, high performance complementary polysilicon emitter bipolar transistors are described. The influence of the base biasing resistance, emitter geometry and temperature on the noise spectra are discussed. The npn transistors studied exhibited 1/f and shot noise, but the pnp transistors are characterized by significant generation–recombination noise contributions to the total noise. For both types of transistors, the measured output noise is determined primarily by the noise sources in the polysilicon–monosilicon interface. The level of the 1/f noise is proportional to the square of the base current for both npn and pnp transistors. The contribution of the 1/f noise in the collector current is also estimated. The area dependence of 1/f noise in both types of transistors as well as other npn bipolar transistors are presented.