Optimized Switching Behavior Electron-Irradiated Power Semiconductors

By Wilhelm Schneider* | Translated by AI 5 min Reading Time

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Power semiconductors are essential—and must meet the highest demands. Targeted electron irradiation enables precise optimization of electrical properties, thereby improving switching behavior, efficiency, and reliability.

Efficient and time-saving: Through batch irradiation, BGS optimizes multiple power semiconductors simultaneously with electron beams— for high efficiency and reduced process times.(Image: iStock.com/kynny)
Efficient and time-saving: Through batch irradiation, BGS optimizes multiple power semiconductors simultaneously with electron beams— for high efficiency and reduced process times.
(Image: iStock.com/kynny)

Wilhelm Schneider is Key Account Manager for Radiation Crosslinking at BGS Beta-Gamma-Service GmbH & Co. KG

Power semiconductors form the heart of modern high-performance electronics. Whether in electromobility, renewable energy, or industrial drive systems, the demands on these components are continuously increasing. Targeted electron irradiation is a proven method for improving the electrical properties of power semiconductors and optimizing them for use under demanding conditions.

Switching times, energy losses, and thermal load capacity are key optimization parameters. By controlled creation of defects in the crystal lattice, recombination processes can be specifically influenced, improving switching behavior and reducing leakage currents. Compared to traditional doping with heavy metals, electron irradiation offers significant advantages in terms of process precision, reproducibility, and material integrity.

Advantages of Electron Irradiation Compared to Other Methods

Compared to other methods, such as diffusion (e.g., platinum, gold, or palladium diffusion), electron irradiation offers the advantage of avoiding the use of additional doping elements, thereby eliminating the need to alter the chemical composition of the semiconductor material. This particularly prevents precipitation or agglomeration of heavy metals in the semiconductor. This allows for very precise control of switching times and the depletion region capacitance of the semiconductor. Furthermore, electron irradiation can be conducted at relatively low temperatures, minimizing thermal stress on the semiconductor and preserving the integrity of the crystal lattice. The temperature required for stabilizing the generated defects is below 518°F. Additionally, the leakage current generated by the irradiation in the blocking state is relatively low. Notably, by selecting the annealing temperature and irradiation dose, it is also possible to control the ratio of double vacancies and oxygen/vacancy complexes created by electron irradiation in silicon, thus tailoring the properties of these recombination centers depending on the current density in the semiconductor.

Another key advantage of electron irradiation is its flexibility: by adjusting the electron fluence and irradiation energy, the type and density of the generated defects can be tailored. This allows for very specific tuning of semiconductor properties, enabling the components to be optimized for different applications, whether for fast switching operations or for operation under high voltages. The vertically generated distribution of minority carrier lifetime also appears significantly different compared to diffusion. While electron irradiation results in a well-reproducible, vertically and laterally homogeneous minority carrier lifetime, diffusion produces a lateral and vertical inhomogeneity, making it much more susceptible to process-related variations. In diffusion, the lateral distribution of silicon vacancies plays a particularly critical role, being both inhomogeneous and poorly reproducible. For example, getter processes have a significant influence on this vacancy distribution. Another advantage of electron irradiation is that the heavy metals traditionally used to lower carrier lifetime are becoming increasingly expensive.

In summary, electron irradiation offers a highly precise and flexible alternative to methods like platinum diffusion for tuning recombination centers and optimizing the switching behavior of power semiconductors. This makes it a crucial tool in modern semiconductor technology, contributing to the continuous improvement of the performance and reliability of these components. Compared to conventional methods like the diffusion of heavy metals, this technology provides significant advantages, including a more homogeneous distribution of recombination centers, lower leakage currents, and more flexible adjustment of semiconductor properties. In various high-performance applications, electron-irradiated power semiconductors make a decisive difference in terms of efficiency, reliability, and performance.

Electron-Irradiated Power Semiconductors: Key Technology for Many Industries

Durable: Modified diodes and thyristors increase the energy efficiency and lifespan of motor controls, especially in manufacturing automation applications.(Image: iStock.com/alvarez)
Durable: Modified diodes and thyristors increase the energy efficiency and lifespan of motor controls, especially in manufacturing automation applications.
(Image: iStock.com/alvarez)

Electron-irradiated power semiconductors play a vital role in smart grids, where they enable the fast and efficient switching of large electrical currents and voltages. This capability is crucial for the regulation and stability of modern energy distribution systems. Smart grids are a fundamental component of the energy transition, as they efficiently integrate decentralized electricity generated from renewable energy sources such as solar and wind power into the grid.

The use of electron-irradiated power semiconductors in smart grids significantly enhances the reliability and efficiency of power networks. Their optimized switching properties enable more precise control of energy flows, which is particularly important given the fluctuating input from renewable sources. Their ability to switch between blocking and conducting states in microseconds plays a key role in stabilizing the grids. The smart energy market is growing rapidly and is projected to increase from $170 billion in 2022 to $283 billion by 2027. Electron-irradiated power semiconductors are an essential technological component of this development and contribute significantly to improving energy efficiency.

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Electron-treated power semiconductors such as MOSFETs and IGBTs are also used in electromobility. Their applications range from electric drives to the power electronics employed. They make a positive contribution to the efficiency and reliability of these systems, which is especially important under extreme operating conditions like high temperatures and heavy loads. Power semiconductors in electric vehicles benefit in several ways from electron-irradiated semiconductors. On the one hand, they enable more efficient energy use thanks to reduced switching losses, which translates into an increased range. On the other hand, they ensure greater reliability of the power electronics, which is crucial given the high demands on vehicle safety and durability. Modern wide-band-gap (WBG) semiconductors such as silicon carbide (SiC) also offer advantages like higher efficiency and better temperature stability. However, electron irradiation can also be applied to these new materials.

Photovoltaics: Electron irradiation enables precise defect control and optimizes thermal stability and switching performance.(Image: iStock.com/ewg3D)
Photovoltaics: Electron irradiation enables precise defect control and optimizes thermal stability and switching performance.
(Image: iStock.com/ewg3D)

Electron-irradiated fast diodes and thyristors enable increased energy efficiency and extended lifespan of motor controls in industrial drives and automation. The precisely adjustable switching properties of these components allow for better control of high-performance motors. Frequency converters, used for the speed regulation of electric motors, also benefit from electron-irradiated power semiconductors. Thanks to their improved switching properties, they can control motors more precisely while consuming less energy. This enhances the overall efficiency of industrial plants, reduces operating costs, and lowers CO₂ emissions.

In the power electronics of photovoltaic systems, silicon-based semiconductors are used, characterized by high blocking voltages and improved dynamic properties. Electron irradiation enables the optimization of switching behavior in such semiconductors. These advancements indirectly contribute to improving the overall efficiency of inverter systems, whose performance depends on the properties of the semiconductors used. This represents an important contribution to enhancing the economic viability of photovoltaic systems.

Tailored Performance for High-Performance Applications

Electron-irradiated power semiconductors offer significant advantages over conventional semiconductors for numerous applications. Their precisely adjustable electrical properties allow for highly accurate adaptation to specific requirements, whether for fast switching operations or operation under high voltages. Electron irradiation thus represents a technologically and economically attractive alternative to traditional methods like metal diffusion, especially as the latter faces rising costs. With the growing demand for energy-efficient solutions in renewable energy technology, e-mobility, and industrial drive systems, the importance of electron-irradiated power semiconductors will continue to increase. Their role as key components in modern power electronics makes them essential building blocks for the energy transition and the electrification of various economic sectors. The continuous advancement of irradiation technologies, such as stack irradiation, contributes to cost reduction. Combined with advanced semiconductor materials like silicon carbide, electron irradiation also opens up new possibilities for further improving the performance and reliability of electronic systems. (mr)