John D. Cressler, Emmanuel F. Crabbé, et al.
IEEE Electron Device Letters
We report the experimental observation of a novel effect in SiGe heterojunction bipolar transistors (HBT's) with graded bases which results in a significant emitter-base bias dependence of the current gain. The nonideal collector current is caused by the interaction of the bias dependence of the emitter-base space-charge region width and the exponential dependence of the collector current on the germanium concentration at the edge of the space-charge region. The resulting current gain rolloff must be taken into account for accurate modeling of bipolar transistors with bandgap grading in the base. © 1993 IEEE
John D. Cressler, Emmanuel F. Crabbé, et al.
IEEE Electron Device Letters
John D. Cressler, Emmanuel F. Crabbé, et al.
IEEE Transactions on Electron Devices
John D. Cressler, James H. Comfort, et al.
IEEE Transactions on Electron Devices
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