Diamond wafers to make meaner, greener electronics

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London, Apr 8 (ANI): Japanese scientists have said that diamond chips could pave the way for a new generation of greener, more powerful electronics.

Pure diamond is a super-tough electrical insulator, but given the right impurities it becomes a semiconductor. Crucially, it is also the best thermal conductor on Earth.

All the above properties mean synthetic diamond could be used to make microchips that handle high-power signals but do not require power-hungry cooling systems.

"Diamond-based control modules in electric cars and industrial machinery could lead to considerable energy savings," New Scientist quoted Hideaki Yamada of National Institute of Advanced Industrial Science and Technology (AIST) in Tsukuba, Japan, as saying.

However, making diamond wafers big enough for economic mass production has been a stumbling block.

Synthetic diamond is made using a process called chemical vapour deposition (CVD), in which a plasma of methane or other hydrocarbon gas deposits carbon onto a surface "seeded" with diamond particles. When the wafer has been grown, it is etched off the seed layer.

But until now, the largest diamond wafers made like this have been around a centimetre square and a couple of millimetres thick.

To grow them further, the researchers first tried using CVD to bond several smaller wafers together.

The technique worked - but it created a patchwork of misaligned crystal lattices unsuited to making transistors.

And thus, Yamada and his colleague Akiyoshi Chayahara used the same seed diamonds to make a series of small wafers, with the result that the wafers were "clones", all with the same crystal lattice.

Then the researchers could use CVD to join them up seamlessly.

Using that method the team made 25-millimetre-square wafers from six smaller "cloned" wafers.

"It certainly has sufficient potential for fabricating electronic devices. Better still, our method does not limit the area of the wafer," said Yamada.

In the next year his group is aiming to produce 50-by-50 millimetre and 75-by-75 millimetre wafers.

A paper on the new diamond wafers was presented at a meeting of the Japan Society of Applied Physics at Tokai University. (ANI)

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