Researchers quantify factors for reducing power semiconductor resistance by two-thirds

December 5, 2017, University of Tokyo
Electron scattering under the silicon carbide (SiC) interface is limited by three factors: roughness of the SiC interface, charges under the SiC interface and atomic vibration. Credit: 2017 Mitsubishi Electric Corporation.

A research group in Japan announced that it has quantified for the first time the impacts of three electron-scattering mechanisms for determining the resistance of silicon carbide (SiC) power semiconductor devices in power semiconductor modules. The university-industry team has found that resistance under the SiC interface can be reduced by two-thirds by suppressing electron scattering by the charges, a discovery that is expected to reduce energy consumption in electric power equipment by lowering the resistance of SiC power semiconductors.

Electric power equipment used in home electronics, industrial machinery, trains and other apparatuses requires a combination of maximized efficiency and minimized size. Mitsubishi Electric is accelerating use of SiC devices for power semiconductor modules, which are key components in electric power equipment. SiC power devices offer lower resistance than conventional silicon power devices, so to further lower their resistance it is important to understand correctly the characteristics of the resistance under the SiC .

"Until now, however, it had been difficult to measure separately resistance-limiting factors that determine electron scattering," says Satoshi Yamakawa, senior manager of the SiC Device Development Center at Mitsubishi Electric's Advanced Technology R&D Center.

Electron scattering focusing on atomic vibration was measured using technology from the University of Tokyo. The impact that charges and atomic vibration have on electron scattering under the SiC interface was revealed to be dominant in Mitsubishi Electric's analyses of fabricated devices. Although it has been recognized that electron scattering under the SiC interface is limited by three factors: the roughness of the SiC interface, the charges under the SiC interface and the atomic vibration, the contribution of each factor had been unclear. To confirm the impact of the charges, the researchers fabricated a planar-type SiC metal-oxide-semiconductor field-effect transistor (SiC-MOSFET), in which electrons conduct away from the SiC interface to around several nanometers.

The research results show that the roughness of the SiC interface has little effect in limiting resistance, while charges under the SiC interface and atomic vibration are dominant factors. Credit: 2017 Mitsubishi Electric Corporation.

"We were able to confirm at an unprecedented level that the roughness of the SiC interface has little effect while charges under the SiC interface and atomic vibration are dominant factors," says Koji Kita, an associate professor at the University of Tokyo's Graduate School of Engineering and one of scientists leading the research.

Using an earlier planar-type SiC-MOSFET device for comparison, resistance was reduced by two-thirds owing to suppression of electron scattering, which was achieved by making the electrons conduct away from the charges under the SiC interface. The previous planar-type has the same interface structure as that of the SiC-MOSFET fabricated by the electronics maker.

For the test, Mitsubishi Electric handled the design, fabrication and analysis of the resistance-limiting factors and the University of Tokyo handled the measurement of electron-scattering factors.

"Going forward, we will continue refining the design and specifications of our SiC MOSFET to further lower the of SiC devices," says Mitsubishi Electric's Yamakawa.

Explore further: Reusing waste energy with 2-D electron gas

Related Stories

Reusing waste energy with 2-D electron gas

November 20, 2017

More than 60 percent of the energy produced by fossil fuels is lost as heat. Thermoelectric energy conversion has attracted much attention as a way to convert waste heat from power plants, factories and cars into electricity. ...

Low-resistance contacts move germanium electronics forward

November 11, 2016

Researchers at the University of Tokyo demonstrate that using germanides of metals at the metal-germanium interface with suitable surface crystal planes, greatly improves the contact resistance and device performance germanium ...

Deep-depletion: A new concept for MOSFETs

October 26, 2017

Silicon has provided enormous benefits to the power electronics industry. But performance of silicon-based power electronics is nearing maximum capacity.

How well electron transport works in furfural biogas

September 13, 2017

Furfural is a promising candidate in the quest for alternative biofuels. The combustion industries are very interested in what could become a potential new type of fuel derived from atmospheric-plasma treatment of biomass. ...

Recommended for you

How community structure affects the resilience of a network

June 22, 2018

Network theory is a method for analyzing the connections between nodes in a system. One of the most compelling aspects of network theory is that discoveries related to one field, such as cellular biology, can be abstracted ...

The pho­to­elec­tric ef­fect in stereo

June 22, 2018

In the photoelectric effect, a photon ejects an electron from a material. Researchers at ETH have now used attosecond laser pulses to measure the time evolution of this effect in molecules. From their results they can deduce ...

Water can be very dead, electrically speaking

June 21, 2018

In a study published in Science this week, the researchers describe the dielectric properties of water that is only a few molecules thick. Such water was previously predicted to exhibit a reduced electric response but it ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.