Power Electronics Using Coherent Silicon Carbide

Silicon Carbide (SiC) is an inorganic semiconductor material with an extremely wide bandgap that can alternately act as either an electrical conductor or insulator, making it useful in power electronics due to its superior electrical conductivity over traditional silicon semiconductors.

EAG Laboratories has extensive expertise in performing bulk and spatially resolved analytic techniques on SiC samples.

High-temperature power electronics

Electric Vehicles (EVs) require power semiconductor devices capable of operating at higher temperatures, lower energy losses and faster switching speeds than those made of regular silicon chips. Wide-band gap materials like SiC can provide these advantages, and have been shown to perform well in laboratory experiments; however, making integrated circuits from it may present unique challenges; its supply chain may not yet be as developed as for regular silicon.

Coherent’s team is working hard to reduce SiC costs and shorten production timelines, so manufacturers can increase EV efficiency while meeting consumer performance demands.

Coherent’s Saxonburg, Pennsylvania plant employs silicon-on-insulator (SOI) technology to manufacture high-performance SiC epitaxial wafers up to 200 mm in diameter using silicon-on-insulator (SOI) techniques. These wafers can be used in fabricating various power electronics devices like MOSFETs and IGBTs as well as GaN-on-SiC RF power amplifiers and other microwave devices.

Coherent’s SOI process gives greater control over the growth of SiC layers, thus improving yield and device performance. Coherent offers comprehensive characterization capabilities including Laser Ablation-Inductively Coupled Plasma-Optical Emission Spectroscopy (LA-ICP-OES) and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), both useful tools in identifying critical defects and increasing yield.

High-frequency RF power amplifiers

With the rapid expansion of 5G networks worldwide, demand for RF power amplifiers to strengthen transmission of wireless data signals has seen exponential growth. Coherent is providing silicon carbide wafers capable of functioning effectively within these new high-frequency bands on an expandable technology platform.

SiC substrates from this company help power electronics run more efficiently by reducing heat production, thus decreasing cooling system sizes – saving energy costs while saving on cooling system space requirements.

SiC semiconductors can operate at higher frequencies than pure silicon chips, increasing speed and range in electric cars. Furthermore, SiC semiconductors produce less waste heat while withstanding higher temperatures – this means they can power more efficient vehicles with better fuel economy.

Coherent’s joint investment with Japanese firms Denso and Mitsubishi Electric will enable it to increase production of 200mm silicon carbide substrates and epitaxial wafers, as well as establish arm’s length long-term supply arrangements to satisfy the Japanese firms’ 150 mm and 200mm SiC requirements. Furthermore, this deal strengthens Coherent’s position in the automotive market – it already supplies materials used to make chips used for auto parts and electronics manufacturing – with each investing $500 million each for 12.5% non-controlling ownership stake in their new business unit.

Automotive electronics

Power electronics made from coherent silicon carbide enable vehicles to become more energy efficient and reliable, reduce carbon dioxide emissions, and speed the transition toward a sustainable society. They enable regenerative braking technology – which converts heat energy from braking into electrical energy which can then be stored in an electric vehicle battery – as well as controlling and operating larger electrical loads such as heaters, fans and e-machines.

Coherent has announced the formation of Silicon Carbide LLC as its new SiC business subsidiary, to produce GaN-on-SiC MOSFETs and other RF and microwave devices on high quality semi insulating SiC wafers of up to 200mm diameter. According to Coherent, Denso Automotive – one of the major automotive suppliers – and Mitsubishi Electric have both invested significantly.

Coherent’s investments will enable its capacity expansion plans and ensure a reliable, scalable supply for meeting growing market demands for SiC-based power electronic devices. Coherent anticipates significant cost savings through using SiC, which is significantly less expensive than traditional semiconductor materials like silicon chips. Furthermore, SiC can withstand higher temperatures than silicon chips which allows manufacturers to shrink cooling systems, thus decreasing weight and space requirements of products – an important consideration as automotive companies strive to reduce vehicle costs while increasing consumer acceptance of EVs.

Energy storage

SiC chips provide energy storage systems with greater efficiency and power density by lowering switching losses, operating at higher temperatures with reduced current loss, as well as helping to decrease component sizes and costs while simultaneously decreasing component sizes and costs. Furthermore, this technology facilitates smaller cooling systems, further decreasing system volume and weight.

SiC is an excellent material for magnetic field sensing due to its natural magnetic resonance which can be leveraged for applications involving field detection. Furthermore, its spin coherence time is 10 times greater than conventional semiconductors allowing for fast and accurate measurements that make SiC suitable for high-speed, compact low power high resolution magnetometers.

Studies on defects in SiC have employed electron paramagnetic resonance (EPR) and electrically detected magnetic resonance (EDMR), with particular attention paid to carbon vacancies present in as-grown CVD layers that exhibit long spin coherence times at room temperatures9.10,35.

Khan stresses the importance of his Coherent subsidiary working closely with leading system companies to maximize learning. Understanding customer and end user decision drivers – like, for instance, electric vehicle market requirements such as initial purchase cost/operating cost ratio, driving range/charging time balance is vitally important, according to Khan.

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