Resonant Tunneling Diodes in Terahertz Applications

Resonant tunnelling diodes (RTDs) exploit quantum tunnelling through a double‐barrier heterostructure to generate and detect electromagnetic waves in the terahertz (THz) band. Their inherent negative differential resistance enables compact oscillators and mixers with operation extending beyond 1 THz. Materials systems such as InGaAs/AlAs and AlGaAs/GaAs have been refined to improve peak-to-valley current ratios, spectral purity and output power. Integration with microwave cavities, varactor tuning elements and mutually coupled antenna arrays has driven advances in frequency tuning, power combining and beam shaping. RTD-based coherent receivers and detectors benefit from injection locking and self-oscillation mixing to enhance sensitivity at room temperature. These devices underpin a broad range of applications, from high-resolution imaging and spectroscopy to high-capacity wireless links, nondestructive testing and precision radar, promising miniaturised, low-power THz systems with global significance in communications, security and biomedical diagnostics.

Research from Nature Portfolio

Recent studies have demonstrated a single-element RTD oscillator acting as both source and coherent receiver through self-oscillating mixing and injection locking. This approach achieved over 20 dB sensitivity enhancement compared with direct detection and enabled 30 Gbit/s real-time, error-free wireless transmission without error correction. The compact system reduces size and power consumption, illustrating the potential of RTD-based coherent detection for THz sensing, imaging and high-speed communications in a variety of scientific and industrial contexts.

Resonant Tunneling Diodes in Terahertz Applications publication trend

The graph below shows the total number of articles in resonant tunneling diodes in terahertz applications across all publications each year (not limited to Nature Index journals).

Technical terms

Resonant tunnelling diode: Semiconductor device with a double‐barrier quantum well that permits electron tunnelling at discrete energies, producing negative differential resistance.

Terahertz waves (THz): Electromagnetic radiation in the frequency range of approximately 0.1–10 THz, situated between microwave and infrared bands.

Negative differential resistance: Phenomenon in which an increase in applied voltage leads to a decrease in current, enabling self-sustained oscillations.

Injection locking: Process by which an oscillator’s frequency and phase are synchronised to an external signal, improving spectral stability and coherence.

Quantum well: Thin semiconductor layer confining charge carriers in one dimension, resulting in discrete energy levels and resonant transport behaviour.

References

1. Bistability of AlGaAs/GaAs Resonant-Tunneling Diodes Heterostructural Channel. Sensors (2023).
2. InGaAs/AlAs Resonant Tunneling Diodes for THz Applications: An Experimental Investigation. IEEE Journal of the Electron Devices Society (2018).
3. Terahertz coherent receiver using a single resonant tunnelling diode. Scientific Reports (2019).
4. High‐speed error‐free wireless data transmission using a terahertz resonant tunnelling diode transmitter and receiver. Electronics Letters (2016).
5. Frequency Limitations of Resonant-Tunnelling Diodes in Sub-THz and THz Oscillators and Detectors. Journal of Infrared, Millimeter, and Terahertz Waves (2019).
6. A High-Power Terahertz Source Over 10 mW at 0.45 THz Using an Active Antenna Array With Integrated Patch Antennas and Resonant-Tunneling Diodes. IEEE Transactions on Terahertz Science and Technology (2022).
7. Sensitive terahertz-wave detector responses originated by negative differential conductance of resonant-tunneling-diode oscillator. Applied Physics Letters (2020).
8. Absolute and Precise Terahertz-Wave Radar Based on an Amplitude-Modulated Resonant-Tunneling-Diode Oscillator. Photonics (2018).