Parasitic energy barriers in SiGe HBTs |
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Authors: | Slotboom JW Streutker G Pruijmboom A Gravesteijn DJ |
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Affiliation: | Philips Res. Lab., Eindhoven; |
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Abstract: | Parasitic energy barriers can easily be introduced during processing. Measurements and calculations of experimental n-p-n HBTs (heterojunction bipolar transistors) are presented, showing that a parasitic conduction-band barrier at the base-collector junction reduces the collector current and the cutoff frequency. A simple analytical model explains the fT degradation, caused by the reduction of the collector current and a pileup of minority carriers in the base. With the model the effective height and width of the barrier can also be derived from the measured collector current enhancement factor IC(SiGe)/IC(Si) |
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