Characterization and Modeling of Silicon-on-Insulator Lateral Bipolar Junction Transistors at Liquid Helium Temperature

Conventional silicon bipolars are not suitable for low-temperature operation due to the deterioration of current gain ( $\bm{\beta}$ ). In this article, we characterize lateral bipolar junction transistors (LBJTs) fabricated on silicon-on-insulator (SOI) wafers down to liquid helium temperature (4 K). The positive SOI substrate bias greatly increases the collector current and has a negligible effect on the base current, thus significantly alleviating $\bm{\beta}$ degradation at low temperatures. We present a physical-based compact LBJT model for 4 K simulation, in which the collector current ( $\textit{I}_\textbf{{C}}$ ) consists of the tunneling current and the additional current component near the buried oxide (BOX)/silicon interface caused by the substrate modulation effect. This model is able to fit various characteristics of LBJTs well and has promising applications in amplifier circuits simulation for silicon-based qubits signals.