We present an investigation of low-frequency noise in advanced vertical <i>pnp</i> bipolar junction transistors (BJTs) with
differing interfacial oxide thicknesses (10Å, 12Å, and 14Å). Low-frequency noise is observed to exhibit a cubic
dependence on IFO thickness. Devices were measured across the temperature range of 90 K to 450 K. From 90 K to 250
K, the magnitude of the low-frequency noise is found to decrease with temperature, but from 250 K to 450 K the noise
actually increases with temperature. Devices were hot-carrier (electrically) stressed, and the low-frequency noise was
found to be almost unchanged with the addition of stress-induced traps. The transparency fluctuation model is suggested
as a possible explanation for the operative noise mechanism, due to the similar dependence of base current and low-frequency
noise on interfacial oxide thickness.