Hot Electron Transistor Technologies in Two-Dimensional Materials

Hot electron transistors (HETs) exploit carriers injected or accelerated to energies significantly above thermal equilibrium, enabling rapid switching and high‐frequency performance beyond conventional device limits. The integration of two‐dimensional (2D) materials such as graphene, transition metal dichalcogenides and hexagonal boron nitride offers unparalleled control over carrier injection, base thickness and interface quality. Atomically thin layers serve as near‐ideal bases or tunnelling barriers, minimising scattering and enabling ballistic transport of hot electrons. Mixed‐dimensional heterostructures—combining 2D conductors with bulk semiconductors or oxides—have broadened the design space for hot‐emitter, graphene‐base and heteroepitaxial transistor architectures. Advances in material synthesis, transfer techniques and interface engineering have led to submillivolt subthreshold swings, high current densities and negative differential resistance, paving the way for ultra-low-power logic, reconfigurable multi-valued circuits and terahertz amplification. Practical realisation hinges on scalable fabrication of uniform atomically thin films and precise control of Schottky barriers, making this field a focal point for next-generation electronics in the post-Moore era.

Research from Nature Portfolio

Recent studies have demonstrated a hot-emitter transistor based on stimulated emission of heated carriers in double mixed-dimensional graphene/germanium Schottky junctions. This device achieves a subthreshold swing below one millivolt per decade and exhibits a peak-to-valley current ratio exceeding 100 at room temperature. Multi-valued logic with high inverter gain and reconfigurable logic states has been realised, marking a significant advance for low-power and negative-differential-resistance applications.

Earlier demonstrations of dual-mode operation in 2D-material-base hot electron transistors employed graphene or MoS₂ as an ultrathin base. By reversing the collector-base potential, devices could switch between hot-electron and reverse-current modes at room temperature, with dynamically tunable current gain. This multifunctional operation highlights the versatility of 2D bases for flexible, high-density and low-energy applications.

Hot Electron Transistor Technologies in Two-Dimensional Materials publication trend

The graph below shows the total number of articles in hot electron transistor technologies in two-dimensional materials across all publications each year (not limited to Nature Index journals).

Technical terms

Hot electron: Charge carrier possessing kinetic energy well above the thermal equilibrium level.

Two-dimensional material: Atomically thin crystal with strong in-plane bonds and weak interlayer interactions.

Schottky barrier: Energy barrier formed at a metal–semiconductor junction that controls carrier injection.

Subthreshold swing: Gate-voltage change required to vary drain current by one decade in a transistor.

Negative differential resistance: Electrical characteristic where current decreases with increasing voltage.

Ballistic transport: Carrier motion over a distance without scattering events, preserving high energy.

References

1. A hot-emitter transistor based on stimulated emission of heated carriers. Nature (2024).
2. Dual-mode operation of 2D material-base hot electron transistors. Scientific Reports (2016).
3. High Gain Graphene Based Hot Electron Transistor with Record High Saturated Output Current Density. Advanced Electronic Materials (2023).
4. Material considerations for the design of 2D/3D hot electron transistors. APL Materials (2021).
5. Vertical Transistors Based on 2D Materials: Status and Prospects. Crystals (2018).