The effects of electrical stress on static characteristics and power spectral density,SIb,of base current,Ib,fluctuations at low frequencies,f<1kHz, have been studied in quasiself-aligned bipolarn-p-njunction. In as-fabricated devicesSIb∝1/AE,whereAEis the transistor emitter area, whereas in strongly degraded transistorsSib∝1/PE,wherePEis the transistor perimeter. The latter demonstrates directly that hot carrier-induced noise sources are generated at the periphery of the transistors, in agreement with former work on hot electron-induced aging of bipolar junction transistors. ©1997 American Institute of Physics.