GaN and application understanding

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GaN and application understanding [Copy link]

GaN technology has not only gained traction in power and RF electronics, but is also rapidly expanding into other applications, including digital and quantum computing electronics. This article outlines future GaN device technologies and advanced modeling methods that can push the boundaries of these applications in terms of performance and reliability. While GaN power devices have recently been commercialized in the 15-900 V category, new GaN devices are highly desirable for exploring higher voltage and ultra-low voltage power applications. Moving into the RF domain, ultra-high frequency GaN devices are being used to implement digital power amplifier circuits, and further developments using hardware-software co-design methods can be expected. On the horizon is GaN CMOS technology, the key missing piece to realize a full GaN platform with integrated digital, power, and RF electronics. Although currently a challenge, high-performance p-type GaN technology is essential to realize high-performance GaN CMOS circuits. Due to its excellent transport properties and the ability to generate free carriers through polarization doping, GaN is expected to become an important technology for ultra-low temperature and quantum computing electronics. Finally, given the increasing cost of hardware prototyping for new devices and circuits, the expected future trend is toward technology-circuit co-design using high-fidelity device models and data-driven modeling approaches. In this regard, physically inspired, mathematically robust, computationally inexpensive, and predictive modeling approaches are essential.

GaN devices are gaining wider acceptance as a technology that demonstrates numerous advantages in power electronics applications, RF, and more recently in digital and ultra-high and ultra-low temperature electronics. A key advantage of GaN technology is its unique ability to operate in very high and very low temperature environments. Due to its unique material properties, including a wide bandgap and excellent transmission parameters, GaN can meet the high temperature, high frequency, and high power requirements of a wide range of industrial applications5,6 including deep well drilling, automotive, and aerospace. At the same time, GaN-based devices can operate in extremely low temperature environments associated with superconducting and quantum computing applications. Due to its polarization-induced doping, GaN can overcome the carrier freezing challenges of other technologies such as doped silicon.

The power semiconductor industry focuses on a wide range of applications, from lighting and power grids to automotive. Currently, GaN high electron mobility transistor (HEMT) products are commercialized and can operate in the range of 15-650 V. Compared with Si, GaN HEMTs offer higher switching frequencies and are therefore widely used in high-speed wireless charging and electrified transportation. Vertical GaN power devices on native substrates are close to commercialization,10,11 while vertical structures fabricated on foreign substrates, such as low-cost silicon, sapphire, and engineered substrates, are also under research. In addition to high-voltage products, GaN technology also provides unique opportunities for ultra-low voltage products (e.g., below 15 V). The new generation of GaN devices based on the superjunction concept shows great advantages in power applications.

Currently, RF is the next most notable application of GaN technology. GaN-based power amplifiers (PAs) offer significantly enhanced RF performance (i.e., power density and bandwidth) compared to PAs based on conventional technologies. To further improve PA efficiency and bandwidth for mmWave operation, this paper discusses the digitization of PAs and the hardware-software co-design at the device and circuit levels. At the device level, novel epitaxial heterostructures and architectures, such as vertical device designs that leverage knowledge gained from GaN power electronics applications, offer better thermal distribution, higher breakdown voltage, and power density compared to lateral structures. We also briefly discuss innovations such as 3D electron gas gradient channel devices, FinFET technology, and digital GaN CMOS technology14 to improve RF linearity.

For digital and ultra-low temperature applications, GaN offers significant advantages over silicon and III-V technologies. GaN’s wide bandgap suppresses band-to-band tunneling and gate-induced drain leakage, thereby reducing static power consumption. However, there are still many challenges to be addressed, one of which is the lack of high-performance p-FET GaN, a necessary technology for practical implementation of CMOS circuits. Another challenge is related to the high defect density of GaN-on-Si wafers, but engineered substrates are expected to produce better results.

Quantum computing electronics is the next frontier for GaN technology applications. Advances in qubit management and related components hold promise for large-scale hardware integration or/and the potential for “quantum computing on a chip.” We see exciting new avenues of research in low-temperature GaN CMOS electronics for control and readout operations in quantum computing, as well as the use of nitrogen-vacancy (NV) centers as robust qubits in III-nitride technology.

The paper concludes with a discussion of GaN device modeling, emphasizing that modeling can be used as a tool to complement traditional experimental methods in performance and reliability studies. Given that GaN devices are often limited by degradation mechanisms, especially those introduced by traps and mechanical and thermal stresses, it is necessary to develop modeling frameworks that combine reliability physics with carrier dynamics. In addition, circuit-compatible compact device models and process design kits must be developed to enable co-design and co-optimization of materials-device-circuit-software and to achieve cross-integration of different GaN technologies.