Wide-bandgap semiconductors

Gallium nitride semiconductors are compound semiconductors, made from Gallium (Ga) and Nitride (N).

Wafers made solely from GaN would be too costly to produce. Here manufacturers have a trick up their sleeve: They use silicon wafers – and apply an ultra-thin layer of gallium nitride. This highly complex metal-organic chemical gas deposition takes place at Infineon in special reactors: Here silicon wafers are exposed to various vaporized chemicals at a temperature of 1200 degrees Celsius. In a complex chemical reaction, the GaN layer, which is only a few thousandths of a millimeter thick, is created from the gaseous materials in several hours.

The electronic circuits are then attached to this layer. Due to the special arrangement of the gallium nitride on the silicon base material, the current in the chips runs parallel to the surface, whereas with SiC it runs through the chip. Although this means that GaN chips cannot process quite as high voltages, they can on the other hand switch extremely quickly with almost no loss.

With changing lifestyles, digitalization and the ongoing push for artificial intelligence, data volumes are also growing exponentially. At the same time, we see energy consumption in data centers strongly increasing. According to the IEA, in 2022 data centers consumed around 2% of the world's total electricity (= 460 TWh). The key questions are: Where is energy needed, for what and how can demand be reduced?

Did you know that data centers use up to 50% of their energy for cooling and backup power alone? There is a great need for alternative energy solutions. In addition to established semiconductors, in particular new wide-bandgap technologies like silicon carbide (SiC) and gallium nitride (GaN) play a crucial role. GaN technology alone has a global savings potential of 21 TWh annually. Looking at the impact of all Infineon technologies together (Si, SiC, GaN), we could potentially save the incredible amount of 48 TWh.

GaN transistors (HEMTs) allow us to push the frontiers for both energy efficiency and space. Technically speaking, they pave the way for up to 98.5 percent efficiency in 48 V servers and a power density of up to 100 W/inch³ for 12 V servers. CoolGaN™ transistors increase switching frequencies by a factor of 10 and reduce energy loss by up to 50% in any given power supply.

As a result, data centers can handle more power in the same or less space and need less cooling energy. For data center operators this means significant savings on operational expenditures and capital expenditures. And this means a huge savings potential on CO₂ emissions for our environment.

Today's chargers for communication devices need to be small, powerful, and reliable. Not to mention green! But what about energy lost during voltage conversion? How can these losses be avoided? The secret lies in getting the semiconductor technology right.

Just imagine: If every smartphone charger worldwide used Infineon power components, we would save the electricity consumed every year by all homes in a big city like Munich. In other words, we could save around 2.3 GWh, which corresponds to more than 1000 tons of CO₂ equivalent!

1. State-of-the-art microelectronics inside chargers and adapters can reduce waste heat. The semiconductor technology gallium nitride (GaN) is particularly effective. GaN transistor components enable a higher switching frequency in the voltage converter while keeping loss at very low levels. In simple terms, GaN semiconductors translate into significant electrical energy savings in chargers.
2. In addition, GaN technology enables higher power densities. Devices become smaller without compromising on performance or charging time.
3. Finally, GaN power stages and transistors are driving the USB-C standard. It is expected that USB-C will save 11,000 tons of e-waste every year.

Get deeper insights into Infineon's GaN portfolio here

Silicon carbide semiconductors are compound semiconductors made of Silicon (Si) and Carbon (C). Compared to "traditional" silicon, the production of SiC is highly complex.

Although SiC occurs naturally as carborundum, it is too impure in nature, so the crystals have to be grown, just like silicon. While silicon crystals grow to a meter long within two days at around 1500 degrees, silicon carbide needs up to two weeks at 2400 degrees to grow a raw crystal, called a puck, that is at most ten centimeters long. In the next step, fine diamond wires are used to cut this puck into extremely thin wafers. About half of the material is lost during sawing and grinding.

But there is a solution: Infineon works with a separation technology called "Cold Split". A laser creates a "defect layer" onto which a polymer is applied. During cooling, the semiconductor and the polymer connected to it expand differently. This causes mechanical stress that splits the wafer. The process has been around for a while, but it only became commercially attractive with silicon carbide. 

Silicon carbide wafers are more expensive than silicon wafers and are extremely thin. However, with the same performance, SiC chips are smaller than Si components by a factor of 5. Therefore, the power handling capability gained per wafer is much bigger.

Globally, there is extensive research relating to SiC. The EU for example is supporting the "European SiC Value Chain for a greener economy" with 89 million euros. And for a good reason: The market is strongly growing to 6.3 billion dollars by 2027 according to the consultancy agency Yole. And SiC has unique advantages for certain industries.

Electric cars, trains and industrial drives consume less electricity, solar modules can feed more power to the grid thanks to a single material: silicon carbide. This semiconductor material unfolds its potential wherever direct and alternating current are converted – between PV modules and the power grid, between batteries and electric motors and between the grid and home storage systems. Considerable amounts of electricity flow in these processes. Energy is usually lost with each power conversion. This can be reduced by SiC – to a high extent. Depending on the area of application, experts see a potential 30 percent loss reduction. That quickly adds up to several megawatt-hours of savings.

The secret of silicon carbide is its wide bandgap. This means that silicon carbide can withstand higher internal electric fields than silicon can, allowing the use of thinner semiconductor layers with lower resistance and correspondingly less power loss. And because of its rigid crystal structure, silicon carbide also withstands higher temperatures and dissipates heat better. Both factors can significantly reduce cooling efforts, leading to massive CO₂ savings potential.

In addition, silicon carbide enables higher switching frequencies. The advantages of this can be seen in inverters. These components "chop" the direct current into many small portions and reassemble them as alternating current. And the higher the switching frequency, the smaller the respective current portions and the smaller the passive components required.

A prominent example where SiC has made significant design miniaturization possible is solar inverters. 

While a 100-kilowatt inverter for a photovoltaic system weighed more than a ton in 2008, modern 125 kW units weigh well under 100 kilograms. Such systems, with an efficiency of up to 99 percent, have already been on the market for a few years.

The special material properties of SiC are ideal: They allow for higher currents than traditional silicon semiconductors of the same chip size with significantly reduced loss. By enabling higher switching frequencies, SiC semiconductors help to massively reduce the size and weight of passive components such as inductors. This enables more compact PV inverters and helps lower system costs. 

In short, Infineon's SiC components help improve the overall efficiency of a solar power plant.

Silicon carbide in electric vehicles enables more efficiency, higher power density and better performance. In particular with an 800 V battery system and a large battery capacity, silicon carbide leads to higher efficiency in inverters and thus enables longer ranges and lower battery costs. SiC furthermore improves the efficiency and power density of the on-board charger. The material enables bi-directional power flow, from the grid to the battery and vice versa. SiC also has a positive impact on battery management: It enables greater vehicle range with the same battery size, or smaller and lighter batteries with the same range.

In addition, charging with the respective infrastructure can be much faster thanks to SiC. Thinking further, power semiconductors foster sustainability: Highly efficient vehicles have lower weight due to optimized battery capacity, less cooling effort and optimized wire harnesses. This enables a sustainable circular lifecycle and reduces raw materials consumption. 

In short, Infineon's SiC system solutions help improve the overall efficiency of the vehicle – especially in the drive train, the traction inverter and the on-board charger. 

Get deeper insights into Infineon’s SiC portfolio here