High Electron Mobility Transistor Devices and Applications

High electron mobility transistors (HEMTs) exploit a heterostructure to confine a high-mobility two-dimensional electron gas at the interface between wide-bandgap semiconductor layers. This architecture permits exceptionally low on-resistance, high breakdown voltages and rapid switching speeds, making HEMTs a cornerstone of modern power electronics and radio-frequency amplification. Gallium nitride (GaN) and aluminium gallium nitride (AlGaN)/GaN heterostructures have emerged as the leading material system, owing to their wide bandgap, high critical electric field and excellent thermal conductivity. Applications range from high-efficiency DC-DC converters and compact EV inverters to millimetre-wave communications and radar. Recent advances in normally-off (enhancement-mode) designs have improved safety and integration in power converters, while novel insulator and gate architectures address issues of gate leakage, threshold-voltage stability and trapping-induced dispersion. The convergence of materials science, epitaxial growth, device engineering and circuit integration continues to extend the performance envelope of HEMTs, with global significance for energy efficiency, sustainable transport and next-generation wireless networks.

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Recent reviews of stability and reliability have synthesised the dynamic-switching behaviour of GaN HEMTs, detailing the impact of trapping effects on on-resistance and threshold-voltage drift under high-voltage stress. The analysis emphasises strategies for buffer optimisation and surface passivation that mitigate current collapse, ensuring robust operation under avalanche, overvoltage and extreme-temperature conditions.

Monolithic GaN power integration has been demonstrated in both microwave monolithic integrated circuits (MMICs) and smart power IC platforms. Lateral GaN devices integrated with passive components have enabled DC-DC converters operating above 1 MHz with efficiencies exceeding 95 %, while RF amplifiers achieve improved power-added efficiency through optimised gate lengths and load-pull designs.

Advanced AlN/GaN HEMT architectures for millimetre-wave operation have achieved record performance at 40 GHz and 94 GHz, with gate lengths below 100 nm yielding ft/fmax above 60/300 GHz. These devices combine high output power density with low leakage and exhibit negligible degradation during extended RF stress tests, illustrating the potential for high-frequency radar and 5G applications.

High Electron Mobility Transistor Devices and Applications publication trend

The graph below shows the total number of articles in high electron mobility transistor devices and applications across all publications each year (not limited to Nature Index journals).

Technical terms

High Electron Mobility Transistor (HEMT): A field-effect transistor that uses a heterostructure to confine electrons in a high-mobility channel, achieving superior speed and power performance.

Two-dimensional electron gas (2DEG): A layer of electrons confined at a semiconductor interface, providing high carrier mobility and low scattering.

Threshold voltage: The gate voltage at which a transistor channel begins to conduct appreciable current, determining normally-on or normally-off operation.

On-resistance (RON): The resistance between drain and source when the transistor is fully on, influencing conduction losses.

Breakdown voltage: The maximum drain-source voltage a device can withstand before avalanche or catastrophic failure occurs.

References

1. An Overview of Normally-Off GaN-Based High Electron Mobility Transistors. Materials (2019).
2. Insulated gate and surface passivation structures for GaN-based power transistors. Journal of Physics D (2016).
3. Stability, Reliability, and Robustness of GaN Power Devices: A Review. IEEE Transactions on Power Electronics (2023).
4. GaN Power Integration for High Frequency and High Efficiency Power Applications: A Review. IEEE Access (2020).
5. High Performance and Highly Robust AlN/GaN HEMTs for Millimeter-Wave Operation. IEEE Journal of the Electron Devices Society (2019).
6. Review of GaN HEMT Applications in Power Converters over 500 W. Electronics (2019).