Stretching diamonds shows promise for next-gen electronics

January 05, 2021 //By Nick Flaherty
Stretching diamonds shows promise for next-gen electronics
A team at City University of Hong Kong have reduced the bandgap of diamond to make it emit photons using strain for new photonic and quantum devices.

A joint research team led by City University of Hong Kong (CityU) has demonstrated for the first time the large, uniform tensile elastic straining of microfabricated diamond arrays through a nanomechanical approach. This stretching of the diamond lattice changes the bandgap, allowing photon emission to open up the potential of strained diamond in photonics, and quantum information technologies.

The research was co-led by Dr Lu Yang, Associate Professor in the Department of Mechanical Engineering (MNE) at CityU and researchers from Massachusetts Institute of Technology (MIT) and Harbin Institute of Technology (HIT).

"This is the first time showing the extremely large, uniform elasticity of diamond by tensile experiments. Our findings demonstrate the possibility of developing electronic devices through 'deep elastic strain engineering' of microfabricated diamond structures," said Lu.

However nanoscale diamond can be elastically bent with large local strain, and the latest study showed how this phenomenon can be used for developing functional diamond devices.

"I believe a new era for diamond is ahead of us," he said.

Diamond is well established as a high-performance electronic and photonic material due to its ultra-high thermal conductivity, exceptional electric charge carrier mobility, high breakdown strength and ultra-wide bandgap for high-power or high-frequency devices. "That's why diamond can be considered as 'Mount Everest' of electronic materials, possessing all these excellent properties," Dr Lu said.

The large bandgap and tight crystal structure of diamond make it difficult to dope to create a semiconductor. One potential alternative is strain engineering, using a very large lattice strain to modify the electronic band structure and associated functional properties, but this has been challenging as a result of the strength of the diamond lattice.

The team firstly microfabricated single-crystalline diamond samples from a solid diamond single crystals. The samples were in bridge-like shape - about one micrometre long and 300 nanometres wide, with both ends wider for gripping.  

The diamond bridges were then uniaxially stretched in a well-controlled manner within an

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