Effects of Substrate Bias on Low-Frequency Noise in Lateral Bipolar Transistors Fabricated on Silicon-on-Insulator Substrate

This letter presents a systematic study of how the substrate bias (V-sub) modulation affects the current-voltage (I-V) characteristics and low-frequency noise (LFN) of lateral bipolar junction transistors (LBJTs) fabricatedon a silicon-on-insulator (SOI) substrate. The current gain (beta) of npn LBJTs at low base voltage can be greatly improved by a positiveVsub as a result of enhanced electron injection into the base near the buried oxide (BOX)/silicon interface. However, an excessive positive V-sub may also adversely affect the LFN performance by amplifying the noise generated as a result of carrier trapping and detrapping at that interface. Our results provide a practical guideline for improving both beta and the overall noise performance when using our LBJT as a local signal amplifier.