低温高注入硅双极晶体管电流增益的定理模拟

本文了基区复合电流，发射结空间电荷区复合电流，基区高主入引起的禁带变窄效应，Ｅａｒｌｙ效应，基区和发射区电导调制效应，有效基区展宽效应以及发射区电流集边效应，定量地模拟了硅双极晶体管电流增益在７７Ｋ和３００ｋ时与集电极电流的关系，并且与实验结果相吻合。     

低温高注入硅双极晶体管电流增益和特征频率的定量模拟

本文定量地模拟了硅双极晶体管电流增益和特征频率与集电极电流在77K和300K时的关系，计算结果与实验相吻合．结果表明在77K时，电流增益大注入效应由基区电导调制效应和发射区电流集边效应决定，而在300K时则由有效基区展宽效应决定，特征频率在300K时主要由基区渡越时间决定，而在77K时，由于发射区禁带变窄效应非常明显，以至于发射区少于存贮时间可能成为主要因素．低温下特征频率蜕变的主要原因是禁带变窄效应，而不是低温浅能级杂质陷阱效应．     

大电流时晶体管电流增益下降的物理原因

正 1.引言 众所周知,晶体管的电流增益与收集极电流有关,开始它随收集极电流增大而增大,达到一最大值后,它又随收集极电流的进一步增大而逐渐减小。所谓大电流时电流增益下降,就是指收集极电流大于电流增益达最大值所对应的收集极电流后电流增益下降的现象。 关于大电流时电流增益下降的物理原因,过去有两种解释:一是由Webster提出的基区电导调制效应;另一是由Kirk提出的有效基区展宽效应     

低温大注入多晶硅发射极硅双极晶体管电流增益的定量模拟

已有的理论和实验都已证明，多晶硅发射极硅双极晶体管适合于低温工作，但至今为止，其完整的大注入时电流增益的理论分析还不成熟，特别是进行定量的计算。本文定量地模拟了低温７７Ｋ和常温３００Ｋ下多晶硅发射极硅双极晶体管电流增益与集电极电流密度的关系，并且分析了低温和常温下决定该晶体管电流增益大注入效应的主要物理效应。     

硅双极晶体管低温电流增益模型修正

多晶硅发射区双极晶体管的低温（７７Ｋ）电流增益模型建立在理想掺杂近似的基础上．本文由基区电子电流密度Ｊｎ和发射区空穴电流密度Ｊｐ出发，根据实际掺杂情况中的近似高斯分布，分析了理想掺杂近似对电流增益结果的影响，指出引用这一近似在常温下偏差较小，在低温下则会出现较大的误差．在此基础上，对多晶硅发射区双极晶体管低温电流增益模型作了修正．结果表明，修正后的模型与ＰＩＳＣＥＳ模拟结果取得了较好的吻合．     

发射区复合对AlGaAs／GaAsHBT特性的影响

采用将发射区体内复合及表面复合归一化为载流子寿命变化的方法，用一维模拟程序，能简便地研究发射区复合对ＡｌＧａＡｓ／ＧａＡｌＨＢＴ特性的影响，计算结果表明，发射区载流了寿命的变化几乎不影响注入到基区的电子电流，但却成反比例地影响基区空穴电流，由于降低寿命增大了空穴复合电流，从而降低了ＨＢＴ的电流增益。     

晶体管非线性失真分析

本文从器件物理和结构上提出双极型晶体管非线性失真模型。模型包含8个参量:(1)有效基区展宽效应;(2)发射极电流集边效应;(3)基区电导调制效应;(4)发射结电阻的非线性效应;(5)发射结电容的非线性效应;(6)集电结电容的非线性效应;(7)寄生电容的非线性效应;(8)电流放大系数和雪崩倍增效应与电压的非线性关系。利用Taylor级数展开分析各模型参数,并编制了计算程序,定量计算了互调失真与工作频率、发射极条宽、基区宽度、发射极线电流密度,基区掺杂浓度等重要参数的关系。计算结果与实验结果基本吻合。     

AlGaAs／GaAs HBT表面效应的二维数值分析

采用表面效应集总模型综合考虑表面费米能级钉扎和表面复合效应，对ＡｌＧａＡｓ／ＧａＡｓＨＢＴ表面效应的影响进行了二维数值模拟。结果表明，表面态的存在对集电极电流几乎不产生影响，但显著增加基极电流，使得电流增益明显下降。同时还发现在台面结构ＡＩＧａＡｓ／ＧａＡｓＨＢＴ中外基区表面复合的集边效应，即外基区表面复合主要发生在发射极台面与外基区的交界处附近，与外基区长度基本无关。模拟还表明基区缓变结构可以减少表面复合，提高电流增益。     

硅低温双极晶体管的优化设计与制备：II结构与电特性分析

本文在前文器件掺杂分布优化设计的基础上，实现了结构设计和工艺选择，采用多晶硅发射极技术，研制成功了７７Ｋ下高增益（ＨＦＥ可达２５０）硅双极晶体管；采用多晶硅发射区和基区重掺杂技术，获得了可与ＣＭＯＳ结构兼容，基区电阻较小的硅低温双极晶体管。     

基区重掺杂对SiGe HBT热学性能的影响

相对于同质结晶体管,异质结双极晶体管(HBT)由于异质结的存在,电流增益不再主要由发射区和基区掺杂浓度比来决定,因此可以通过增加基区掺杂浓度来降低基区电阻,提高频率响应,降低噪声系数,但基区掺杂浓度对器件热特性影响的研究却很少。以多指SiGeHBT的热电反馈模型为基础,利用自洽迭代法分析了基区重掺杂对器件集电极电流密度和发射极指温度的影响。通过研究发现,随着基区浓度的增加,SiGe HBT将发生禁带宽度变窄,基区反向注入发射区的空穴电流增大;同时,基区少子俄歇复合增强,这些都将减小集电极电流密度,降低发射极指温度,从而抑制发射极指热电正反馈,提高器件的热稳定性。     

A high-current-gain low-temperature pseudo-heterojunction bipolartransistor utilizing sidewall base-contact structure (SICOS)

An experimental pseudo-heterojunction bipolar transistor (HBT) is described. The pseudo-HBT is a homojunction bipolar transistor having a moderately doped emitter and a heavily doped base, providing a bandgap profile similar to those of actual HBTs. Analyses including real constraints, such as a heavily doped emitter region for ohmic contact and the profile tail in the base region, show a significant change in the way they affect injection characteristics between 300 and 77 K. Based on these analyses, an impurity profile is carefully designed for upward mode operation. The electron injection into the external base region. which is thought to be unfavorable for high current gain in the upward mode, is avoided by using the sidewall base-contact structure. The fabricated transistor clearly displays a negative temperature dependence on current gain. The current gain is 107 at 77 K, which is 5 times higher than the room-temperature current gain. In addition, current gain excluding the nonideal effects at 77 K is as high as 25,000. These results not only remove gain degradation at low temperatures, but also verify the pseudo-HBT concept, in which an injection efficiency as high as that of an HBT can be obtained using only homojunctions. Based on these results, the small emitter transit time inherent in pseudo-HBTs is analyzed     

Some aspects of current gain variations in bipolar transistors

This paper deals with the study of the main mechanisms involved in the bipolar transistor current-gain variations.In the first part, we describe some properties of characteristic parameters N_S and I_SR of the surface “diode”; an attempt is made to explain the strong correlation between N_S and I_SR.In a second part, we analyse the influence of emitter current crowding, high injection in the base region, and base widening effects on the high level bias current gain value. Critical current densities beyond which each of these effects takes place are defined, allowing us to evaluate their comparative importance at a given collector current value. Our study shows that, on the one hand, for transistors affected by emitter-current crowding, the surface currents play an essential part in the high level bias current gain fall off and, on the other hand, the base widening effect has a very great influence on the static (I_C, V_EB) characteristic and on the emitter injection efficiency value.In the third part, the experimental results obtained are reported and compared with previously proposed analytical relations.     

Low-temperature (77 K) BJT model with temperature dependences onthe injected condition and base resistance

A low-temperature (77-K) bipolar transistor model based on physical analysis by considering the temperature dependences of the injection condition and base resistance modulation is described. A charge-based injection factor which describes the temperature dependence of the ideality factor n is introduced by taking into account the electron and hole concentration ratios at the edges of the emitter-base depletion layer. The temperature dependence of base resistance modulation is explained by using the temperature dependences of the conductivity modulation effect, the base pushout effect, and the emitter current-crowding effect. Calculations using the model are compared with measurements, revealing excellent agreement over a wide temperature range from 50 to 298 K     

GaAs inversion-base bipolar transistor (GaAs IBT)

A completely new type of GaAs bipolar transistor with a base formed by a two-dimensional hole gas has been fabricated. The transistor has no metallurgical base layer but has an extremely thin inversion hole layer working as a base layer. The current gain β = 5.6 at 77 K and β = 17.1 at 300 K was obtained for the common emitter mode.     

Delay analysis of BiNMOS driver including high current transients

The BiNMOS gate delay analysis including high current transients has been developed. The modeling equations account for the high electric field effect in the nMOS transistor and emitter crowding, base pushout, and base conductivity modulation in the bipolar transistor. In examining the switching transient of a BiNMOS driver, the base pushout mechanism exhibits a detrimental effect on the gate propagation delay. The circuit modeling methodology provides a fast turn-around design evaluation of sensitivity of process and device parameters into circuit performance. Computer simulation of a BiNMOS driver using the present analysis is compared with PISCES device simulation in support of physical reasoning     

低温多晶硅发射极晶体管电流增益和截止频率的解析模型

本文综合考虑了多晶硅发射极的载流子输运障碍,界面氧化物遂穿、晶粒间界杂质分凝和界面能带弯曲等因素,以及禁带变窄效应、低温下载流子冻析效应和浅能能补偿杂质隐阱效应,建立了低温多晶硅发射极晶体管电流增益和截止频率的解析模型,对电流增益和截止频率的温度关系进行了理论分析并与３００Ｋ和７７Ｋ下的实测结果进行了比较。     

Factors limiting current gain in power transistors

The combined effect of sidewall injection, bandgap narrowing, and Shockley-Hall-Read and Auger recombination in determining emitter efficiency in n-p-n power transistor structures is demonstrated by utilizing a two-dimensional transistor model. The relative importance of each of these effects is calculated as a function of emitter junction depth, emitter surface doping, and injection level. It is shown that in a practical transistor design the reduction in emitter efficiency due to the increased injection of holes into the emitter, resulting from bandgap narrowing caused by heavy doping, is not dominated by the emitter sidewall. Auger recombination is seen to be especially important when bandgap narrowing is present. Enhanced Auger-type recombination is due both to increased minority carrier injection in the emitter as well as current crowding effects. The predictions of the model are compared with results of the measurement of current gain versus current level characteristics on existing devices.     

77K多晶硅发射区双极型晶体管

本文介绍了适于77K工作的多晶硅发射区双极型晶体管,给出了在不同工作电流条件下的电流增益的温度模型。结果表明在小电流条件下电流增益随温度下降而下降得更为剧烈,并且讨论了在不同注入情况下,浅能级杂质的陷阱作用对截止频率的影响。     

Analytical modelling of current gain and frequency characteristics under high injection levels in Si/SiGe heterojunction bipolar transistors at 77 and 300 K

This paper reports an analytical modelling of current gain and frequency characteristics in Si/SiGe heterojunction bipolar transistors (HBTs) at 77 and 300 K. Important transistor parameters, such as current gain, transconductance, cutoff frequency and maximum oscillation frequency are calculated as a function of Ge concentration in the base under different injection levels. The main physical mechanisms for the current and cutoff frequency rolloff at high injection levels are also analyzed. It shows that the high-level injection effect is more pronounced in the SiGe HBTs as a result of the increasing minority carrier concentration in the base and the Ge concentration and distribution will have a decisive influence of device performance. The results may provide a basis for the design of low temperature operation SiGe HBTs.     

选择离子注入集电极技术研究

为提高超高速双极晶体管的电流增益 ,降低大电流下基区扩展效应对器件的影响 ,将选择离子注入集电区技术 (SIC)应用于双层多晶硅发射极晶体管中。扩展电阻的测试结果显示出注入的 P离子基本上集中在集电区的位置 ,对发射区和基区未造成显著影响。电学特性测量结果表明 ,经过离子注入的多晶硅发射极晶体管的电流增益和最大电流增益对应的集电极电流明显高于未经离子注入的晶体管。因此 ,在双层多晶硅晶体管中采用 SIC技术 ,有效地降低了基区的扩展效应 ,提高了器件的电学特性。