Investigating the Differences in Low-Frequency Noise Behavior of npn and pnp SiGe HBTs Fabricated in a Complementary SiGe HBT BiCMOS on SOI Technology

摘要

We present a comprehensive investigation of the fundamental differences in low frequency noise behavior between npn and pnp SiGe HBTs. Geometry effects on the low frequency noise are assessed, as well as the impact of interfacial oxide (IFO) thickness on pnp noise characteristics. Temperature measurements and ionizing radiation are used to probe the fundamental physics of 1/f noise in npn and pnp SiGe HBTs. The npn transistors show a stronger size dependence than the pnp transistors. The 1/f noise for pnp SiGe HBTs exhibits an exponential dependence on IFO thickness, indicating that IFO produces the main contribution. In most cases, the magnitude of the 1/f noise has quadratic dependence on the base current (I_B), the only exception being for the post-radiation npn transistor biased at low base currents, which exhibits a near-linear dependence on I_B. In the proton radiation experiments, the pnp devices show better radiation tolerance than the npn devices. The observed temperature dependence for both types is quiet weak, consistent a tunneling mechanism.