The evolution of wide band gap materials has been keeping pace as new technology demands looks for advance performance and reliability. Their ability to operate at higher temperatures, higher power densities, higher voltages and higher frequencies make them highly interesting for use in future electronic systems. Two very important wide bandgap materials showing great promise for the future for both switching and RF power applications are Gallium Nitride (GaN) and Silicon Carbide (SiC). As innovation becomes more competitive and rigorous the debate between Gallium Nitride (GaN) versus Silicon Carbide (SiC) material has taken pace. The semiconductor devices which are possible and which device / material is best suited for various switching and RF power applications.
Critical Field of GaN and SiC
The high critical field of both GaN and SiC compared to Si is a property which allows these devices to operate at higher voltages and lower leakage currents. Higher electron mobility and electron saturation velocity allow for higher frequency of operation. While SiC has higher electron mobility than Si, GaN’s electron mobility is higher than SiC meaning that GaN should ultimately be the best device for very high frequencies. Higher thermal conductivity means that the material is superior in conducting heat more efficiently.
Characteristics of SiC and GaN
This wider bandgap makes GaN highly suitable for optoelectronics and is key to producing devices such as UV LEDs where frequency doubling is impractical. Not only do GaN semiconductors have 1000 times the electron mobility than silicon they are also able to operate at higher temperatures while still maintaining their characteristics (up to 400 degrees Celsius). These combined characteristics would make GaN highly desirable in high frequency (THz), high temperature, and high power environments.
WBG benefits include:
- Elimination of up to 90% of the power losses that occur during power conversion.
- Up to 10X higher switching frequencies than Si-based devices.
- Operation at higher maximum temperature than Si-based devices.
- Systems with reduced lifecycle energy use.
Although WBG semiconductors now cost more than silicon devices, they may eventually be competitive as manufacturing capabilities improve and market applications grow. Several challenges must be addressed to make WBG materials more cost-effective, including:
- Production of larger-diameter WBG wafers.
- Use of novel designs that exploit the properties of WBG materials.
- Use of alternative packaging that enables higher-temperature WBG devices.
- Design of systems that integrate WBG devices so that they take advantage of their unique capabilities.
GaN and SiC semiconductor materials allow for smaller, faster, more reliable devices with higher efficiency than their silicon-based cousins. These capabilities make it possible to reduce weight, volume, and lifecycle costs in a wide range of power applications. Figure 1 compares the breakdown voltage and on-resistance of Si, SiC, and GaN devices.
Wide Bandgap Semiconductors
Gallium nitride (GaN) and silicon carbide (SiC) are relatively similar in both their bandgap and breakdown field. Gallium nitride has a bandgap of 3.2 eV, while silicon carbide has a bandgap of 3.4 eV. While these values appear similar, they are markedly higher than silicon’s bandgap. At just 1.1 eV, silicon’s bandgap is three times smaller than both gallium and silicon carbide. The compounds’ higher bandgap allows gallium nitride and silicon carbide to support higher voltage circuits comfortably, but they cannot support lower voltage circuitry as well as silicon.
Breakdown field Strength
Gallium nitride and silicon carbide’s breakdown fields are relatively similar to each other, with gallium nitride boasting a breakdown field of 3.3 MV/cm, while silicon carbide has a breakdown field of 3.5 MV/cm. When compared to plain silicon, these breakdown fields make the compounds significantly better equipped to handle higher voltages. Silicon has a breakdown field of 0.3 MV/cm, which means that gallium nitride and silicon carbide are nearly ten times more capable of maintaining higher voltages. They are also able to support lower voltages using significantly smaller devices.
Wafer Manufacturing Processes
Current manufacturing processes are the limiting factor for both gallium nitride and silicon carbide, as these processes are either more expensive, less accurate, or more energy-intensive than widely adopted silicon manufacturing processes. Gallium nitride, for example, contains a massive number of crystal defects over a small area. Silicon, on the other hand, can contain as few as 100 defects per square centimeter. Before this century, manufacturers had been unable to create GaN substrates with fewer than one billion defects/cm. Obviously, this tremendous rate of defects made GaN incredibly ineffective. While manufacturers have made strides in recent years, GaN still struggles to meet stringent semiconductor design requirements.
Power semiconductors are used in the field of power electronics. Using solid-state devices, power electronics control and convert electrical power in systems. These include cars, cellphones, power supplies, solar inverters, trains and wind turbines. Power semiconductors play a key role in the conversion process. There are different types of power semis, and each one is denoted by a numerical figure with a “V,” or voltage. “The ‘V’ as in VDSS is the maximum allowed operating voltage, or drain-source voltage specification,” explained Alex Lidow, chief executive of Efficient Power Conversion (EPC). “The terminology ‘DSS’ means drain-to-source with the gate shorted.”
GaN and SiC Power Semiconductor Market
Energized by demand from hybrid & electric vehicles (HEVs), power supplies and photovoltaic (PV) inverters, the global market for silicon carbide (SiC) and gallium nitride (GaN) power semiconductors is forecast to grow to $854m by the end of 2020 (up from just $571m in 2018) then surpass $1bn in 2021, according to Omdia’s ‘SiC & GaN Power Semiconductors Report – 2020’. Revenue is expected to increase at a double-digit annual rate for the next decade, surpassing $5bn by 2029. These long-term market projection totals are about $1bn lower than those in last year’s edition of the report because demand for almost all applications has slowed since 2018. Moreover, device average prices fell in 2019. Omdia adds a note a caution: the equipment forecasts used to create this year’s forecast all date from 2019, and do not take account of the impact of the COVID-19 pandemic. SiC Schottky diodes have been on the market for more than a decade, with SiC metal-oxide-semiconductor field-effect transistors (SiC MOSFETs) and junction-gate field-effect transistors (SiC JFETs) appearing in recent years. SiC power modules are also becoming increasingly available, including hybrid SiC modules, containing SiC diodes with silicon insulated-gate bipolar transistors (IGBTs), and full SiC modules containing SiC MOSFETs with or without SiC diodes.
SiC MOSFETs are proving popular among manufacturers, notes Omdia, with several companies already offering them. Several factors caused average pricing to fall in 2019, including the introduction of 650V, 700V and 900V SiC MOSFETs priced to compete with silicon superjunction MOSFETs, as well as increasing competition among suppliers.
Wide-Bandgap Power (WBG) Semiconductor Devices Industry
Global Wide-Bandgap Power (WBG) Semiconductor Devices Industry” is projected to reach a revised size of US$5.6 Billion by 2027, growing at a CAGR of 33.5% over the analysis period 2020-2027. UPS and PS systems, one of the segments analyzed in the report, is projected to record a 31.6% CAGR and reach US$2.3 Billion by the end of the analysis period. After an early analysis of the business implications of the pandemic and its induced economic crisis, growth in the PV inverters segment is readjusted to a revised 36.6% CAGR for the next 7-year period. The U.S. Market is Estimated at $198.7 Million, While China is Forecast to Grow at 41.4% CAGR. The Wide-Bandgap Power (WBG) Semiconductor Devices market in the U.S. is estimated at US$198.7 Million in the year 2020. China, the world`s second largest economy, is forecast to reach a projected market size of US$1.5 Billion by the year 2027 trailing a CAGR of 41.1% over the analysis period 2020 to 2027. Among the other noteworthy geographic markets are Japan and Canada, each forecast to grow at 26.7% and 30.5% respectively over the 2020-2027 period. Within Europe, Germany is forecast to grow at approximately 28.7% CAGR.
Industrial motor drives Segment to Record 35% CAGR
In the global Industrial motor drives segment, USA, Canada, Japan, China and Europe will drive the 33.9% CAGR estimated for this segment. These regional markets accounting for a combined market size of US$95.2 Million in the year 2020 will reach a projected size of US$733.6 Million by the close of the analysis period. China will remain among the fastest growing in this cluster of regional markets. Led by countries such as Australia, India, and South Korea, the market in Asia-Pacific is forecast to reach US$901.6 Million by the year 2027, while Latin America will expand at a 36.3% CAGR through the analysis period. We bring years of research experience to this 9th edition of our report. The 216-page report presents concise insights into how the pandemic has impacted production and the buy side for 2020 and 2021. A short-term phased recovery by key geography is also addressed.