A wide bandgap semiconductor is a useful material in many applications because of its ability to withstand high temperatures and high electrical fields. It behaves similarly to other compounds, but has one key feature that differentiates it from others: its bandgap, the energy required for an electron to escape the bond between atoms, is wider than other materials at room temperature.
The bandgap is the energy difference between the valence and conduction bands in a solid. In wide band gap materials, this gap is much larger than that of other compounds at room temperature, making it harder for an electron to move out of its position within a given atom. A strong silicon-oxygen bond inside a crystal is responsible for this great bandgap.
WBG Semiconductors are increasingly used in applications such as supercapacitors and extremely high temperature electrical equipment, such as precision resistive temperature detectors (RTDs) and thermocouples. These materials also make good conductors of electricity at high temperatures, which can come in handy for use in electric vehicles, high temperature power generation equipment, and loudspeakers.
SiC and GaN
When it comes to the next generation of efficient power converter switches, wide band gap semiconductor materials like gallium nitride (GaN) and silicon carbide (SiC) are an excellent choice. Each material, however, has distinct advantages over the others. Silicon carbide power semiconductors, for example, provide excellent voltage blocking for applications starting at 650V and provide significantly greater benefits as voltage increases.
The utilization of these novel WBG power electronics materials, which allow for greater power efficiency, lighter weight, smaller size,lower total cost – or all of these together – is critical for the next critical step towards an energy-efficient world.
In comparison to silicon, silicon carbide (SiC) has a substantially wider bandgap of 3 electronvolts (eV) and a much higher thermal conductivity. SiC-based MOSFETs are ideally suited for high breakdown, high power applications that run at high frequencies.
In comparison to silicon, silicon carbide power semiconductors device characteristics such as RDS(on) rise less with temperature. This enables designers to operate with tighter margins or at higher temperatures in their wide bandgap power electronics designs, resulting in increased performance.
GaN has an even higher bandgap (3.4 electronvolt) and substantially higher electron mobility than SiC. Compared to silicon (Si), the breakdown field is ten times higher and the electron mobility is doubled. Both the output charge and gate charge are ten times lower than with Si, and the reverse recovery charge is almost zero, which is key for high frequency operations.
GaN wide bandgap semiconductor power devices are the technology of choice in modern resonant topologies, offering novel methods such as new topologies and current modulation.
Advantages of Wide Bandgap Semiconductors
There is a long list of wide bandgap semiconductor advantages. For example, higher efficiency brought about by wide bandgap semiconductor-based electronics, leads to increased power density, reduced size and weight, and lower overall system costs.
The use of wide bandgap semiconductor devices in power electronics also aids in the realization of greater working switching frequencies. It’s critical, especially when the goal is ultimate power density. Even at high frequencies, GaN WBG semiconductors have a low total gate charge and a low voltage threshold of about 1.5 V, and gate-drive power is restricted to milliwatts.
Which is better?
There are several distinctions between GaN, SiC, and Si semiconductors. To begin, GaN semiconductors currently target voltages ranging from 80V to 650V and provide medium power at the highest switching frequency. SiC targets above 650V, and the semiconductors are usually available at 1200V or 1700V. GaN and SiC semiconductors have lower switching losses than Si-based semiconductors and have very high efficiency at maximum power density.
When it comes to the differences between GaN and SiC power electronics semiconductors, SiC power semiconductors offer greater gate-oxide dependability, outstanding ease of use, are incredibly durable, and utilise vertical transistor principles as opposed to GaN, which is a lateral transistor.
GaN and SiC each contribute unique strengths to the application solution arena. Their advantages, however, are dependent on how they are used. Silicon Carbide, for example, is superior in high-temperature and high-voltage applications such as high-power string inverters. A lower temperature coefficient and high blocking voltage characteristics meet the application demands best for high-temperature capability.
GaN is superior when it comes to ultimate power density. This is especially the case in applications where construction volume is very limited, such as switched-mode power suppliers in data centers since power levels increase in a given space. In this case, efficiency and high switching frequencies are combined to push the application to the next level which are impossible to reach by other technologies.