Improvement of an SiGe HBT Structure by Changing the Germanium Profile (original) (raw)
2011, Australian Journal of Basic and …
Abstract: In this paper, the effect of Ge profile on the characteristics of an SiGe heterojunction bipolar transistor (HBT) is investigated. The serious problem of the HBT structure is the formation of parasitic barriers, due to the addition of germanium dopants to the base. ...
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Microwave and Optical Technology Letters, 2005
In this paper, the effects of Ge content and profile shape on the performance of a SiGe-based heterojunction bipolar transistor (HBT) are investigated. The common-emitter current gain, the early voltage, and the transit time of SiGe HBTs are calculated and computed for different Ge profiles as well as the total Ge content in the base, considering uniform base-doping. Then the effects of the above on the cutoff frequency f and the maximum oscillation frequency fmax of the HBT are shown. It is seen that both the forward current gain and the transit time decrease with the change in profile from box to triangle, but the early voltage increases with a similar change. The increase of Ge content for the same profile results in a decrease of transit time. From the analysis, a large increase in f and fmax can be predicted with a suitable choice of Ge profile and the total Ge content in the base. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 247–254, 2005; Published online in Wiley InterScience (www.interscience.wiley.com).
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