低温硅双极晶体管基区优化设计

常规双极晶体管在７７Ｋ下电流增益和频率性能都严重退化。本文首先分析了低温双极晶体管基区Ｇｕｍｍｅｌ数，基区方块电阻，渡越时间和穿通电压等参数与温度及基区掺杂的关系，然后讨论了低温双极器件基区的优化设计问题。     

硅低温双极晶体管的优化设计与制备─—I．优化设计理论

本文研究了硅双极晶体管电流增益和截止频率的低温物理特性，提出了电流增益在低温下将随发射区杂质浓度的下降和基区杂质浓度的上升而上升的新理论，得出了低温下硅中浅能级杂质将起有效陷阱作用的新结论。在上述基础上，本文对发射区、基区和收集区的掺杂分布进行了优化设计，这将成为获得高性能硅低温双极晶体管的重要设计依据和理论基础。     

硅低温双极晶体管的优化设计与制备：I.优化设计理论

本文研究了硅双极晶体管电流增益和截止频率的低温物理特性，提出了电流增益在低温下将随发射区杂质浓度的下降和基区杂质浓度的上升而上升的新理论，得出了低温下硅中浅能级杂质将起有效陷阱作用的新结论。在上述基础上，本文对发射区、基区和收集区的掺杂分布进行了优化设计，这将成为获得高性能硅低温双极晶体管的重要设计依据和理论基础。     

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．     

工作在液氮温度下的低频低噪声双极晶体管的研究

对双极晶体管的低温物理模型和低频噪声模型进行了研究，认为低温下硅双极晶体管电流增益下降的主要原因是低温下非理想基极电流的增加。同时指出，低温下硅双极晶体管１／ｆ噪声的增大，是由于低温下电流增益的减小和载流子在体内和表面的复合增加。通过优化设计，做出了一种低温、低频、低噪声硅双极晶体管。测试表明，在室温（３００Ｋ）下，电流增益、低频转折频率、１ｋＨｚ点的噪声电压分别为β≥８００，ｆＬ≤３０Ｈｚ，Ｅｎ     

低温低频低噪声双极晶体管

对双极晶体管的低温效应和低温低频噪声特性进行了研究。明确了双极晶体管的电流增益和低频噪声随温度的变化规律。指出低温双极晶体管获得最小噪声电压的途径。     

非晶硅发射区双极晶体管的低温特性

本文研究了非晶硅发射区双极晶体管的低温特性，得出了如下结论：低温下电流增益随基区杂质浓度的上升而下降，不同于常规同质结双极晶体管的情况，集电极电流则随基区杂质浓度的上升而上升。这些结果将为低温双极晶体管的设计提供理论依据。     

在液氮温度下具有高增益的SiGe/SiHBT

本文分析了硅双极晶体管电流增益在低温下减小的原因．通过优化设计，研制出在液氮温度下具有高增益的SiGe／SiHBT，并分析了其工作机理．     

双极晶体管hFE低温失效分析及使用可靠性

论述了影响双极晶体管电流增益ｈＦＥ低温下降的重掺杂效应，结合具体器件测试计算出了ｈＦＥ的低温下降值，并对实测值与计算值的差异进行了分析，最后指出了改进ｈＦＥ温度特性的具体途径。     

工作在液氮温度下的低频低噪声双极晶体管的研究

对双极晶体管的低温物理模型和低频噪声模型进行了研究，认为低温下硅双极晶体管电流增益下降的主要原因是低温下非理想基极电流的增加。同时指出，低温下硅双极晶体管１／ｆ噪声的增大，是由于低温下电流增益的减小和载流子在体内和表面的复合增加。通过优化设计，做出了一种低温、低频、低噪声硅双极晶体管。测试表明，在室温（３００Ｋ）下，电流增益、低频转折频率、１ｋＨｚ点的噪声电压分别为β≥８００，ｆ＿Ｌ≤３０Ｈｚ，Ｅｎ（１ｋＨｚ）≤１．５ｎＶ／　　；低温（７７Ｋ）下，电流增益、低频转折频率、１ｋＨｚ点的噪声电压分别为β≥３０，ｆ＿Ｌ≤３００Ｈｚ，Ｅｎ（１ｋＨｚ）≤１．２ｎＶ／。     

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     

A silicon phototransistor with a MIS tunnel junction emitter

We have fabricated a silicon phototransistor using low-temperature processing. The emitter of the bipolar transistor is an Al-SiO2-p-Si tunnel junction. The quantum efficiency gain is 200 at λ = 0.6328 µm. The common-emitter current gain of the analogous three-terminal metal-insulator-semiconductor (MIS) transistor also is 200. This demonstrates the high minority-carrier injection efficiency of the MIS emitter.     

The temperature dependence of the amplification factor of bipolar-junction transistors

It is widely known that the current gain of the bipolar transistor is degraded by low-temperature operation. However, the temperature dependence of another important parameter, the amplification factor, has not been reported. This brief presents theory and experimental results demonstrating the temperature independence of the Early voltage, and showing as a consequence that the amplification factor is inversely proportional to temperature. Using this information and the bandgap narrowing theory for current gain reduction, predictions and measurements are offered for simple bipolar amplifier circuits. Furthermore, the product of the current gain and amplification factor is proposed as a figure of merit for the transistor. The temperature that optimizes the gain product can be below 100 K for transistors with current gains that are weak functions of temperature.     

A high-current-gain low-temperature pseudo-HBT utilizing a sidewallbase-contact structure (SICOS)

A silicon pseudo-heterojunction bipolar transistor (HBT) with a current gain of over 100 at 77 K has been successfully fabricated using the upward operation of a self-aligned sidewall base-contact structure (SICOS). The measured characteristics agree well with the theoretical prediction, showing a negative exponential temperature dependence of current gain and a 2500-times larger collector current than in the conventional transistor at 77 K. This makes homojunction bipolar transistor operation at low temperatures feasible and has the potential to overcome the bipolar/BiCMOS limitations     

BILOW-simulation of low-temperature bipolar device behavior

The BILOW simulation program for investigating bipolar transistor behavior in the temperature range 77-300 K is discussed. Differences between the numerical approaches required for simulation of low-temperature behavior compared to room-temperature simulation are presented. Efficient numerical models for the physical parameters in the carrier transport equations and Poisson's equation for the temperature range of 77-300 K, including a new highly accurate numerical model for the temperature and doping concentration dependence of carrier mobility, are discussed. A temperature- and doping-concentration-dependent model for apparent bandgap narrowing is also discussed. The internal characteristics of a typical bipolar transistor are simulated over the 300-77 K range. The behavior of current gain β and the unity gain frequency f_T versus collector current density for different temperatures are calculated and discussed     

Current gain of high-low junction emitter bipolar transistor structure with uniformly doped profiles

The analytic expressions for the maximum current gain and the transit times across the neutral emitter and base region in the case of uniformly doped high-low junction emitter bipolar transistor structure are calculated in detail, which include the effects of energy-gap narrowing in highly doped semiconductor, doping-dependent minority-carrier diffusivities, contact-surface and bulk recombinations. It is shown that the high-low junction emitter with the doping in the low-concentration emitter higher than that of the base region will give higher maximum current gain and better frequency response than those of the LEC structure originally proposed by Yagi et al. Numerical results for the optimal design of the high-low junction emitter are given and discussed.     

双极型晶体管电流增益的温度特性研究

分析了大注入效应对双极型晶体管电流增益温度特性的影响,建立了双极型晶体管电流增益温度解析模型。选取产品3DD167来进行不同温度不同工作条件下的测试分析。实验结果表明,在特定工作条件下,该器件在不同温度时其电流增益都有一个零温度点。实验结果和模型吻合较好。     

First hydride free GaInP/GaAs carbon doped HBT grown by CBE usingDMAAs and TBP

A current gain of 120, for a base sheet resistance of 400 Ω/□, is reported in a carbon doped base heterojunction bipolar transistor grown by chemical beam epitaxy (CBE) without hydride sources. This result is to the authors' knowledge, the best obtained with hydride free CBE for this device     

硅低温双极晶体管的数值模拟

本文讨论了有关低温双极器件模拟物理参数的低温模型和各种低温物理效应,确立了适用于低温双极器件模拟的数值分析方法,建立了适用于77-300K温度范围内硅双极器件模拟程序,最后模拟分析了一典型结构品体管的常温和低温时的工作特性。     

发射极-基极-发射极结构PNP型AlGaAs/GaAs HBT电流增益的理论分析

建立了PNP型异质结双极晶体管基区少数载流子浓度的解析模型.理论分析了发射极-基极-发射极布局的PNP型HBT的电流增益.讨论了不同基极电流成分,如外基区表面复合电流,基极接触处的界面复合电流,基区体内复合电流,以及刻蚀台面处的台面复合电流对电流增益的影响.