Journal ArticleDOI
A theory of transistor cutoff frequency (f T ) falloff at high current densities
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In this paper, it was shown that the observed falloff in the f T of a transistor at high currents is due to the spreading of the neutral base layer into the collector region of the device at high current densities.Abstract:
It is shown that the observed falloff in the f T of a transistor at high currents is due to the spreading of the neutral base layer into the collector region of the device at high current densities. The base layer spreading mechanism derives from an analysis of the effect of the current-dependent buildup of the mobile-carrier space-charge density in the collector transition layer. Calculations show that at sufficiently high collector current levels, the mobile space-charge density in the collector transition layer cannot be considered negligible in comparison to the fixed charge density of that region. The over-all effect of taking the mobile space charge into account in analyzing the collector transition region is that, at high current densities, the transition region boundary adjacent to the neutral base layer is displaced toward the collector metal contact with increasing collector current. The attendant widening of the neutral base layer results in the observed, high-current falloff in f T . The application of this theory to transistor structures of both the alloy and mesa variety yields, in each case, calculated curves of f T vs I c which are in reasonably good agreement with experiment.read more
Citations
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Journal ArticleDOI
Gain degradation and enhanced low-dose-rate sensitivity in bipolar junction transistors
TL;DR: In this article, the authors show that the amount of degradation that occurs at a given total dose increases as the dose rate decreases, due to space-charge effects produced by slowly transporting holes and protons in the oxide that covers the emitter-base junction.
Journal ArticleDOI
Designing Ultrahard Bipolar Transistors
C. W. Gwyn,B. L. Gregory +1 more
TL;DR: In this paper, the relative importance of the device regions in establishing the neutron tolerance was analyzed for a bipolar transistor and it was shown that the hardness can be increased substantially by using a device profile with a shallow, abrupt emitter and a narrow base region.
Proceedings ArticleDOI
Monolithic bipolar-, CMOS-, and BiCMOS-receiver OEICs
TL;DR: The possibilities of standard bipolar, CMOS, and BiCMOS processes with respect to their use for the manufacturing of optoelectronic integrated circuits (OEICs) as optical receivers will be compared and the improvement of the OE IC properties due to process modifications and application examples of silicon receiver OEICs will be considered.
Journal ArticleDOI
A new trench bipolar transistor for RF applications
TL;DR: In this article, a new vertical trench SiGe heterojunction bipolar transistor (HBT) is proposed that improves the tradeoff between the cutoff frequency (f/sub T/) and the off-state collector-base breakdown voltage (BV/sub cbo/).
Journal ArticleDOI
Analysis and understanding of unique cryogenic phenomena in state-of-the-art SiGe HBTs
Qingqing Liang,Qingqing Liang,R. Krithivasan,A. Ahmed,Yuan Lu,Ying Li,John D. Cressler,Guofu Niu,Jae-Sung Rieh,Greg Freeman,Dave Ahlgren,Alvin J. Joseph +11 more
TL;DR: In this article, a group of novel device phenomena are reported in state-of-the-art SiGe HBTs operating at cryogenic temperatures, including negative-differential-resistance (NDR) and an unusual "hysteresis" behavior.
References
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