Silicon-based Josephson junction field-effect transistors enabling cryogenic logic and quantum technologies

The continuous miniaturisation of metal-oxide-semiconductor field-effect transistors (MOSFETs) from long- to short-channel architectures has advanced beyond the predictions of Moore’s Law. Continued advances in semiconductor electronics, even near current scaling and performance boundaries under cryogenic conditions, are driving the development of innovative device paradigms that enable ultra-low-power and high-speed functionality. Among emerging candidates, the Josephson Junction Field-Effect Transistor (JJFET or JoFET) provides an alternative by integrating superconducting source and drain electrodes for efficient, phase-coherent operation at ultra-low temperatures. These hybrid devices have the potential to bridge conventional semiconductor electronics with cryogenic logic and quantum circuits, enabling energy-efficient and high-coherence signal processing across temperature domains. This review traces the evolution from Josephson junctions to field-effect transistors, emphasising the structural and functional innovations that underpin modern device scalability. The performance and material compatibility of JJFETs fabricated on Si, GaAs, and InGaAs substrates are analysed, alongside an assessment of their switching dynamics and material compatibility. Particular attention is given to superconductor-silicon-superconductor Josephson junctions as the active core of JJFET architectures. By unfolding more than four decades of experimental progress, this work highlights the promise of JJFETs as foundational building blocks for next-generation cryogenic logic and quantum electronic systems.

💡 Research Summary

This review traces the evolution of the Josephson‑junction field‑effect transistor (JJFET, also called JoFET) from its origins in early superconducting tunnel junction research to the most recent silicon‑based implementations that aim to bridge conventional semiconductor electronics with cryogenic logic and quantum circuits. The authors begin by outlining the fundamental physics of the Josephson effect—coherent tunnelling of Cooper pairs between two superconductors separated by a thin barrier—and how this phenomenon was first exploited in simple Josephson junctions (JJs) for ultra‑fast, low‑dissipation switching. The key conceptual breakthrough that gave rise to the JJFET was the realization that an electrostatic gate could modulate the carrier density in a semiconductor channel placed between superconducting source and drain electrodes, thereby controlling the junction’s critical current (Ic) without the need for magnetic flux biasing.

The paper then surveys the three main material platforms that have been explored for JJFETs: silicon (Si), gallium arsenide (GaAs), and indium‑gallium‑arsenide (InGaAs). Silicon emerges as the most promising substrate for several reasons. First, Si is fully compatible with mature CMOS processing, enabling large‑scale integration and cost‑effective fabrication. Second, the lattice mismatch between Si and common superconductors such as niobium (Nb), aluminum (Al), or titanium nitride (TiN) is modest, allowing epitaxial or high‑quality sputtered growth of superconductor‑Si‑superconductor (S‑Si‑S) stacks with defect densities below 10^10 cm⁻². This high‑quality interface minimizes trap states that would otherwise degrade phase coherence and increase decoherence in quantum applications. Third, low‑temperature transport measurements on Nb/Si/Nb and Al/Si/Al junctions have demonstrated gate‑tunable Ic ranging from a few microamperes down to sub‑nanoampere levels, with a modulation depth exceeding an order of magnitude.

In contrast, GaAs and InGaAs offer higher electron mobility and reduced electron‑phonon scattering, which can be advantageous for high‑speed operation. However, the larger lattice mismatch with superconductors introduces interface defects that limit coherence times and increase noise, making these platforms less suitable for direct integration with superconducting qubits. The authors therefore argue that silicon‑based JJFETs provide the optimal balance of electronic performance, material compatibility, and quantum‑coherent operation.

The review proceeds to a detailed analysis of the switching dynamics of JJFETs. Gate‑induced changes in carrier density translate into rapid variations of the superconducting order parameter in the channel, resulting in critical‑current modulation on sub‑10‑picosecond timescales. This speed surpasses conventional MOSFETs, whose switching is typically limited to >100 ps at cryogenic temperatures. Moreover, because the voltage swing associated with the transition between the superconducting and resistive states is on the order of microvolts, the energy dissipated per switching event falls into the femtojoule (fJ) regime. Such ultra‑low power operation is essential for cryogenic logic families like RSFQ (Resistively Shunted Junction) and SFQ (Single‑Flux‑Quantum), where thermal budgets are extremely tight.

From a system‑level perspective, JJFETs enable a voltage‑controlled paradigm that can replace the traditional current‑biased approach used in many superconducting digital circuits. This shift reduces the number of bias lines, simplifies circuit layout, and improves scalability. The authors also discuss the prospect of three‑dimensional hybrid integration, where superconducting JJFET logic blocks are stacked directly on top of CMOS analog/digital circuitry. This architecture minimizes temperature gradients, shortens interconnect lengths, and allows for seamless interfacing between cryogenic quantum processors and room‑temperature control electronics.

Finally, the paper identifies the remaining challenges that must be addressed before JJFETs can become mainstream building blocks for cryogenic computing and quantum information processing. Key issues include: (1) further reduction of interface trap densities through atomic‑scale epitaxy and surface passivation; (2) development of low‑loss gate dielectrics that retain high dielectric strength at millikelvin temperatures; (3) mitigation of crosstalk and mutual inductance in large JJFET arrays; and (4) reliable modeling of the gate‑controlled Ic dynamics across the full temperature range from 10 mK to a few kelvin. The authors conclude that, once these hurdles are overcome, silicon‑based JJFETs will provide a uniquely energy‑efficient, high‑speed, and quantum‑coherent switching element capable of unifying conventional semiconductor technology with the emerging landscape of cryogenic logic and quantum electronics.