The rise of the wide-bandgap semiconductor has been well documented over the past few years. Offering improved speeds, efficiencies, and operating conditions, new semiconductor materials such as gallium nitride (GaN) and silicon carbide (SiC) have proven highly useful in high-voltage applications. These applications include power electronics, EVs, and the like.
SiC vs. GaN vs. silicon. Image used courtesy of Georgia Tech
So far in 2021, SiC technologies have seen many headlines, spanning from both industry and academia.
For instance, this month ROHM Semiconductor announced the completion of a new plant purpose-built to enhance the company’s SiC production capacity. The new plant, geared to reduce CO2 emissions by 20% over conventional facilities, will employ the most up-to-date SiC manufacturing technologies to improve production efficiency, expand wafer diameter, and increase yield.
ROHM Apollo’s Chikugo plant. Image used courtesy of ROHM Semiconductor
Just this month alone, several research institutions and semiconductor suppliers have released new SiC-based developments that may overcome both the manufacturing and design challenges of this WBG.
R&D Explores How Far SiC Can Go
From the world of academia, a notable SiC headline of 2021 has come from the Nagoya Institute of Technology’s latest research.
The group of researchers has presented a way to non-destructively measure carrier lifetimes in silicon-carbide devices. This is an important achievement since many researchers have been trying to balance SiC carrier lifetimes—looking for the sweet spot between enough conductivity modulation (which requires long carrier lifetimes) and switching losses (which require shorter carrier lifetimes).
In the past, this endeavor has only been measurable through invasive techniques, requiring researchers to literally cut open and analyze the semiconductor.
Proposed non-invasive carrier lifetime measuring technique. Image used courtesy of Nagoya Institute of Technology
In their proposed method, the researchers have used an excitation laser to create carriers and a probe laser with a detector to measure the excited carrier’s lifetimes. With a technique that allows for easier, non-invasive analysis, engineers can finally begin to fine-tune carrier lifetimes to achieve that perfect balance of conduction modulation and low switching losses. This may, in the future, lead to a generation of newer, higher-performing SiC devices.
Another SiC advancement comes from the researchers at Fraunhofer Institute for Solar Energy Systems (ISE), who recently discovered a new type of SiC transistor that can connect directly to the medium-voltage grid because of its high blocking voltages. These new devices are in contrast to most inverters that feed into the low-voltage grid but can couple to the medium-voltage grid using 50 Hz transformers.
The Fraunhofer ISE team created this 250-kVA inverter stack, which included 3.3-kV-SiC-transistors. Image used courtesy of Fraunhofer ISE
Vishay and Cree Look to SiC for Design Simplicity
While academic researchers are making strides in SiC adoption on the R&D front, industry suppliers are also putting more useful SiC-based devices in the hands of practicing engineers.
For example, Vishay recently released new high-efficiency SiC Schottky diodes. The company released 10 brand new SiC diodes, all of which accept a VRRM of 650 V and take forward currents from 4 A to 40 A. The new diodes are rated to withstand a maximum junction temperature of 175°C, allowing for operation in very high-temperature environments—which could be crucial for designers working in certain areas of power electronics.
Specifications of the new SiC Schottky diode family. Image used courtesy of Vishay
The second bit of industry news comes from Cree with the announcement of its Wolfspeed WolfPACK power modules. This new power module was built using Wolfspeed SiC MOSFETs and was specially designed for engineers working in the mid-power range.
According to the company, the goal of the product is to maximize power density while minimizing design complexity. Meant for applications such as EV fast charging and solar, the family is said to offer 1200 V operation with up to 105 A of forward current and an RDS(on) of 11 milliohms at 25°C.
This could greatly benefit designers who are struggling to integrate the right SiC solution because of the pitfalls of design complexity.
A Strong Start for SiC
From academic breakthroughs to new products being brought to market, SiC technology looks poised for rapid growth in the coming years. In fact, some industry analysts predict that the worldwide SiC market will boom from its 2020 status of USD 749 million to USD 1,812 million by 2025.
What experience do you have with SiC power devices—either in a research environment or in hands-on design scenarios? What challenges of this WBG do you hope to see resolved in the next few years? Share your thoughts in the comments below.
