DC and low-frequency-noise characteristics Of SiGe HBTs with a raised-emitter structure, fabricated by epitaxial growth of phosphorous-doped Si layers, were investigated. Experimental results indicate unexpected emitter-size dependencies of both base current and low-frequency noise, because mono-poly interfacial native oxides close to the intrinsic emitter-base junction are localized at the emitter periphery. The raised mono-Si emitter SiGe HBT with a scaled emitter exhibits low-frequency noise that is about ten times smaller than a conventional poly-Si emitter SiGe HBT (c) 2008 Elsevier B.V. All rights reserved.