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

TL;DR

This paper investigates silicon-on-insulator lateral bipolar junction transistors at liquid helium temperatures, revealing how substrate bias improves current gain and presenting a physical model for low-temperature simulation.

Contribution

It introduces a novel physical model for LBJTs at 4 K that accurately fits experimental data and aids in designing low-temperature silicon-based quantum circuits.

Findings

Positive substrate bias enhances collector current at 4 K.

The model accurately fits Gummel characteristics of LBJTs at cryogenic temperatures.

Potential applications in quantum amplifier circuit simulations.

Abstract

Conventional silicon bipolars are not suitable for low-temperature operation due to the deterioration of current gain ($\beta$). In this paper, 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 could greatly increase the collector current and have a negligible effect on the base current, which significantly alleviates $\beta$ 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 the Gummel characteristics of LBJTs very well and has promising applications in amplifier circuits simulation for silicon-based qubits signals.