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Technical Insight

Magazine Feature
This article was originally featured in the edition:
Issue 2 2024

Silicon-based semiconductors – powering ahead


Silicon-based semiconductor technologies, such as power MOSFETs and IGBTs, are essential in every modern power electronics system and play a crucial role in controlling and converting electrical energy. Due to their unique physical properties, these specialized electronic components are designed to handle high voltages and currents, providing benefits and advantages in many different applications, such as renewable energy systems, electric vehicles, power supply for data centres and industrial machines.


A power MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is a type of Field-Effect Transistor (FET). Applying a voltage to the gate terminal, a current will flow through the channel from the drain to the source.
Among the main parameters which affect the most performance of a MOSFET, there are the drain-source resistance RDSon, the gate charge Qg and the breakdown voltage BVDss. In terms of efficiency, lower RDSon means lower conduction losses and higher efficiency in applications where MOSFETs are used to switch current on and off. Lower RDSon also means less heat will be generated during operation, which can reduce the need for heat sinks and other cooling mechanisms. In high-frequency applications, the switching losses might become more significant compared to conduction losses, but having a low RDSon is still beneficial for the overall device performance.

Figure 1 Power transistors technologies.

A lower gate charge allows faster switching speeds, and this is advantageous in high-frequency applications. When a switch commutes, power is dissipated in the form of heat. A lower gate charge can reduce these losses, improving efficiency. The gate charge also determines the current needed from the gate driver to switch the MOSFET at desired speeds. Lower gate charge can lower the requirements on the gate driver circuit.

Figure 2 Planar MOSFET technology.

The breakdown voltage helps determine the maximum voltage that the system can handle. MOSFETs must be chosen with a breakdown voltage higher than the maximum voltage expected in the application. A higher breakdown voltage also provides a larger safety margin, improving the reliability of the MOSFET under transient conditions. Power systems often experience voltage spikes, and having a sufficient breakdown voltage helps protect against these transients. The evolution of silicon MOSFETs from planar to superior structure technology represents a significant advancement in semiconductor design. Planar MOSFETs have a simple structure and are cost-effective for low-power applications, but they face limitations in terms of voltage scaling and drain-source resistance.

Figure 3 High Voltage Silicon MOSFET technology evolution.

A super-junction MOSFET is designed with a more complex structure that includes a series of p-type and n-type regions that are alternately stacked vertically in the drift region, between the gate and the drain. The key factor of the super-junction design is the charge balance between these p-type and n-type regions, which allow for much higher doping concentrations while maintaining the breakdown voltage at the same level. Due to the higher doping levels and the charge balance, super-junction MOSFETs have significantly reduced drain-source resistance compared to that of planar MOSFETs with the same voltage rating. These characteristics enable the ability to handle higher voltages without increasing the physical size of the device, leading to higher efficiency, especially in high-voltage applications. The manufacturing process for super-junction MOSFETs is more complex and requires more precise control than that of planar MOSFETs. Planar MOSFETs are often used in low to medium voltage applications, while super-junction MOSFETs are preferred for high-voltage and high-efficiency applications. In conclusion, the super-junction MOSFET showcase, in addition to a higher dopant concentration, multiple benefits as lower a lower RDSon, improved thermal impedance or the possibility to use the die in thinner packages.