Besides being famous for making beautiful jewellery and for industrial use (extremely effective at polishing, cutting, and drilling) researchers have identified diamonds as advanced functional devices in microelectronics, photonics, and quantum information technologies as well as an ultra-wide bandgap semiconductor to more effectively power the electrical grid, locomotives and even electric cars.
Rudairo Dickson Mapuranga
United States’ Lawrence Livermore National Laboratory Scientists published a study in Applied Physics Letters showing that diamonds have superior carrier mobility, breakdown electric field and thermal conductivity, which are significant properties to power electronic devices.
Following this study, an international team of researchers have certified the importance of diamonds in the tech industry by conducting a study proving that strained diamonds may take a lead in photonics, microelectronics and quantum information technologies.
This means that the use of diamonds can now be shifted to electricity generation and thereby promoting the rise of diamond prices and markets.
Dr. Lu Yang, an Associate Professor in the Department of Mechanical Engineering (MNE) at City University of Hong Kong (CityU) who was one of the heads of the study told the media that a new era for diamonds was approaching the global trend.
“I believe a new era for diamonds is ahead of us,” Dr. Lu Yang said.
In semiconductors, the bandgap is known to be a crucial property and a broad bandgap facilitates the operation of high-frequency or high-power devices.
The big bandgap and tight crystal structure of diamonds creates a problem to “dope,” an easy or common way to control semiconductors’ electronic properties during production. This makes it difficult for diamonds to be used as industrial applications in electronic and optoelectronic devices.
Dr. Lu and his colleagues, however, discovered that nanoscale diamonds can be elastically twisted using an unexpected large local strain. They demonstrated that elastic strain engineering could be used to change the physical characteristics of diamonds thereby becoming essential in microelectronics, photonics, and quantum information technologies.
The team firstly microfabricated single-crystalline diamond samples from solid diamond single crystals. The samples were in a bridge shape about one micrometre long and 300 nanometres wide, with both ends wider for gripping.
The diamond bridges were then uniaxially expanded in a well-controlled way under an electron microscope. Under controllable and continuous loading-unloading cycles of quantitative tensile tests, the diamond bridges exhibited a large and highly uniform elastic deformation of around 7.5 percent strain across the entire gauge section of the sample, instead of deforming at a localized region in bending. And they recovered their original shape after unloading.
Demonstrating the effect of elastic straining between 0 and 12 percent on the electronic properties of diamond, the researchers carried out density functional theory (DFT) with its simulation results indicating that the bandgap of diamonds generally decreased as the tensile strain increased, while the largest bandgap reduction rate decreased from around 5 eV to 3 eV at about 9 percent strain along with a certain crystalline orientation.
The team’s findings represent an early step in realizing deep elastic strain engineering of microfabricated diamonds. The research effectively proved that it is possible to change the band structure of a diamond, and more significantly, such changes can be reversible and continuous, enabling a range of applications, such as strain-engineered transistors, micro/nanoelectromechanical systems
As indicated by Dr. Lu, these findings are an early step in achieving deep elastic strain engineering of microfabricated diamonds proving that indeed a new era for diamonds lies ahead.
This issue first appeared in the January 2021 issue of Mining Zimbabwe Magazine