April 29, 2024

Aluminum Nitride (AlN): Ultra-Wide Bandgap (UWBG) Technology Emerging in the Power Semiconductor Industry

The relentless pursuit of efficiency in energy conversion systems has accelerated the adoption of new materials such as silicon carbide (SiC) and gallium nitride (GaN), which address billions of market needs including electric vehicles (EVs), charging systems, renewable energy Environmentally focused applications such as renewable energy. One of the main distinguishing features of the two technologies is the bandgap (or energy gap), expressed in eV. The bandgaps of SiC and GaN are 3.2eV and 3.4eV respectively, which is three times that of mainstream silicon materials. Among materials with band gaps well above 5 eV (i.e. UWBG) we find diamond, gallium oxide, aluminum nitride, and cubic boron nitride, see Table 1.

Table 1 AlN

Table 1: Physical properties of WBG and UWBG materials

Aluminum Nitride Substrates
Aluminum Nitride Substrates

Why the energy gap is so important

As we all know, the energy gap represents the amount of energy an electron in the valence band must gain to jump to the conduction band, where it can move freely under the influence of an electric field and generate an electric current, so devices such as diodes and transistors can be made. High-band gap transistors can withstand higher electric fields because their atomic bonds are strong. This property reduces on-resistance at high voltages compared to silicon, minimizing conduction losses and helping to improve efficiency. This performance is related to the critical electric field parameters, see Table 1, with AlN and c-BN reaching the highest values.

Recently, researchers have focused on gallium oxide, diamond, and AlN. They all display attractive attributes but inevitably have weaknesses that have hindered their commercial development. However, AlN has become a potential competitor for other materials due to the latest technological advances reported by Nagoya University at the IEEE International Electron Devices (IEDM) event in San Francisco last December.

Areas where AlN is currently used

 Aluminum nitride (AIN) is a non-toxic material with high thermal conductivity and excellent electrical insulation properties. In addition to its thermal expansion coefficient and electrical insulating capabilities, AlN ceramics are resistant to attack by most molten metals such as copper, lithium, and aluminum. AlN is a ceramic material composed of 65.81% Al and 34.19% N. Due to its properties, this ceramic has proven useful in many applications, such as optoelectronic devices operating at deep ultraviolet frequencies. Aluminum nitride is also widely used in applications such as heat sinks and heat sinks, electrical insulators, silicon wafer handling, and processing, as packaging substrates (replacing highly toxic beryllium oxide and aluminum oxide), optical storage media, microwave component packaging, etc. electrical layer.

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