Cubic boron arsenide offers higher thermal conductivity over Silicon. (Image: Christine Daniloff, MIT)

Silicon is one of the most abundant elements on Earth, and in its pure form the material has become the foundation of much of modern technology, from solar cells to computer chips. But silicon’s properties as a semiconductor are far from ideal.

Now, a team of researchers at MIT, the University of Houston, and other institutions has carried out experiments showing that a material known as cubic boron arsenide has two major advantages over silicon. It provides high mobility to both electrons and holes, and it has excellent thermal conductivity. It is, according to the researchers, the best semiconductor material ever found.

So far, cubic boron arsenide has only been made and tested in small, lab-scale batches that are not uniform. The researchers had to use special methods, originally developed by former MIT postdoc Bai Song to test small regions within the material.

More work will be needed to determine whether cubic boron arsenide can be made in a practical, economical form, much less replace the ubiquitous silicon. But even in the near future, the material could find some uses where its unique properties would make a significant difference, the researchers said.

Earlier research had theoretically predicted that the material would have high thermal conductivity; subsequent work proved that prediction experimentally. This latest work completes the analysis by confirming experimentally.

The earlier experiments showed that the thermal conductivity of cubic boron arsenide is almost 10 times greater than that of silicon. They also showed that the material has a very good bandgap, a property that gives it great potential as a semiconductor material.

Now, the new work fills in the picture, showing that, with its high mobility for both electrons and holes, boron arsenide has all the main qualities needed for an ideal semiconductor.

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