Scientists at the Lawrence Livermore National Laboratory in the US published a study in Applied Physics Letters where they present the idea of using diamonds as ultra-wide bandgap semiconductors to more effectively power the electrical grid, locomotives and even electric cars.
In their paper, the researchers said that diamonds have been shown to have superior carrier mobility, breakdown electric field and thermal conductivity, the most important properties to power electronic devices. The gems also became especially desirable after the development of a chemical vapor deposition process for the growth of high-quality single crystals.
Based on this previous knowledge, the team at the LLNL explored properties of synthetically made diamonds that are of higher quality than naturally occurring ones.
“We said to ourselves ‘let’s take this pure high-quality CVD diamond and irradiate it to see if we can tailor the carrier lifetime,’” Paulius Grivickas, lead author of a paper, said in a media statement.
Grivickas explained that in photoconductive devices, the best combination of conductivity and frequency response is achieved by introducing impurities, which control carrier recombination lifetimes. In diamonds, a cheap and easy alternative to this approach is electron irradiation where recombination defects are created by knocking the lattice atoms out of place.
“Eventually, we nailed down the understanding of which irradiation defect is responsible for carrier lifetimes and how does the defect behave under annealing at technologically relevant temperatures,” the researcher said.
Photoconductive diamond switches produced this way can be used, for example, in the power grid to control current and voltage surges, which can fry out equipment. “Current silicon switches are big and bulky, but the diamond-based ones can accomplish the same thing with a device that could fit on the tip of a finger,” Grivickas said.
The scientist pointed out that his findings also have applications in energy delivery systems where there is a possibility of a megawatt-class radio frequency power generation, which requires optimization of diamonds’ high-frequency response.