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

Satake, Hideki; Hamasaki, Toshihiko

doi:10.1109/16.55756

Cited by 15 publications

(3 citation statements)

References 35 publications

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“…The difference in r bb is much more substantial at 43 K, as r bb nearly triples at low injection for the control and new Ge(x) profiles because of carrier freezeout, whose effects can be greatly suppressed with a higher base doping, as shown by the new Ge(x) + higher N B profile data at 43 K. More importantly, the steep r bb vs. I C at 43 K is the combined result of carrier freezeout and base push-out, as modeled in [11], and comes together with higher C cb , which can only be suppressed with higher base doping. This is evidenced by comparing the control and new Ge(x) + higher N B profiles at I C =1.8mA at 43 K, where f T , r bb , and f max improve by 20%, 15%, and 70% in the optimized profile.…”

Section: Discussionmentioning

confidence: 90%

On the profile design of SiGe HBTs for RF lunar applications down to 43 K

Yuan

Cressler

Cui

et al. 2008

2008 IEEE Bipolar/BiCMOS Circuits and Technology Meeting

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New germanium and boron base profiles are designed and tested for emerging lunar RF applications down to 43 K using SiGe HBTs. Device optimization in 1 st generation SiGe HBTs to minimize the carrier freezeout and to suppress the heterojunction barrier effects without changing basic fabrication processes was attempted. Optimizing the device enhances f T by 20% and f max by 70% as compared to a standard HBT, at 43 K. A comprehensive dc and ac investigation from 43 K to 300 K was conducted to demonstrate the capabilities of these newly optimized SiGe HBTs for emerging lunar RF electronics.

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Section: Discussionmentioning

confidence: 90%

On the profile design of SiGe HBTs for RF lunar applications down to 43 K

Yuan

Cressler

Cui

et al. 2008

2008 IEEE Bipolar/BiCMOS Circuits and Technology Meeting

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“…The base resistance RB is relative to Ic, and the effects of conductivity modulation and base push-out should be considered in the high current region, which occur in the whole temperature region [6]. Therefore…”

Section: ' = (Aso)2/[exp(-c~bo) -1 + Abo]mentioning

confidence: 99%

Analysis of transient characteristics of ECL circuit at low temperature

Jiang

Ke-qiang³

et al. 1997

J. of Electron.(China)

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Detailed analysis on transient characteristics of ECL circuits are performed in this paper, then a relatively exact propagation delay expression applied for all temperatures is presented. The cryogenic characteristics of some dominant parameters contributed to propagation delay are also discussed. The model achieved is suitable for optimum designs of high speed devices and circuits at all temperatures.

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“…On the other hand, at the range of temperature lower than 150K, R&, increases exponentially by carrier freeze-out [13,14]. Impact ionization ratio increases monotonously with temperature lowering.…”

Section: Wc~fw~(j~qvnc)/(jc-svn~)~~mentioning

confidence: 94%

A reverse base current under high level injection and its influence on BiCMOS circuit

Ishimaru

Matsuoka

Maeda

et al.

International Electron Devices Meeting 1991 [Technical Digest]

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A reverse base current under high level injection caused by base pushout effect was observed for the first time and investigated in detail. A simple model to study this phenomenon is proposed.The reverse base current induced problem on a BiCMOS circuit is also discussed. This phenomenon causes circuit failure and gives a new limitation factor for applied power supply voltage lower than 0 . 8~ BiCMOS. IntroductionThe advanced BiCMOS circuit has been operated under high level injection condition. With scaling down in the device feature size, this tendency becomes more severe. Under such high level injection, base pushout effect has readily occurred during normal operation. In such condition, the existence of high electric field at N+ buried layer side, which enough to cause impact ionization has been proposed [l]. In this paper. A base pushout induced reverse base current under high level injection was found for the first time. This phenomenon is clearly different from that observed under low level injection [24]. The mechanism of this phenomenon was analyzed. The influence of the reverse base current on the BiCMOS circuit was also discussed as a new limit of maximum power supply voltage. Experimental ProcedureIn this study, the conventional polysilicon emitter bipolar transistors were fabricated by 0 . 8~ BiCMOS process [5]. To estimate the relation between base pushout and reverse base current, bipolar transistor collector conditions were varied. Collector concentration (Nd was varied fmm 5x10'' cm-3 to 1~1 0 '~ cm-3 and collector width (Wc) was varied from 0 . 5~ to 0.9pn, which was estimated by SIMS impurity profile. Other typical device parameters are as follows, current gain hFE is 130, emitter size is 1 x 3~. Bipolar transistor characteristics measurement was carried out at wide ambient temperature range from 77K to U)OK. 2dimensional device simulation (MOS2C [6]) was also carried out to investigate this phenomenon. An R-type BiCMOS inverter was also fabricated and evaluated. Reverse Bast? Current under High Injection LevelA typical Gummel plot of the bipolar transistor at V p 7 V with reverse base current under high level injection is shown in Fig.1. The reverse base current ( I & was observed when emitter-base voltage (V, ) was larger than 0.9V, and when V, exceeds l.lV, the reverse base current disappears. It should be noted that collector current increases drastically when IRB starts to flow. The reverse base current at low level injection condition has been reported which is caused by impact ionization at basecollector depletion region. However, reverse base current at low level injection condition was not observed in this experiment because Nc was low enough to prevent fmm above phenomenon. The reverse base current at such high level injection condition has not been reported. Further, this phenomenon cannot be explained by the previous model [7-101. Figure 2 shows the I-V characteristics of the same device. A snapback phenomenon was observed, which is caused by the existence of the reverse base...

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

Cited by 15 publications

References 35 publications

On the profile design of SiGe HBTs for RF lunar applications down to 43 K

On the profile design of SiGe HBTs for RF lunar applications down to 43 K

Analysis of transient characteristics of ECL circuit at low temperature

A reverse base current under high level injection and its influence on BiCMOS circuit

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