New diamond-boron nitride crystal layer can be used for high-power devices

Materials researchers at North Carolina State University have developed a new technology that combines diamond deposition on a cubic boron nitride surface (c-BN) into a new single-crystal structure. "This material can be used to make high-power equipment such as solid state transformers needed to create the next generation of smart grids," said Jay Narayan, principal chair of materials science and engineering at North Carolina State University and lead author of the paper. "It can also be used to make knives, high-speed cutting and deep-sea drilling equipment," Narayan said. "Diamond is hard but easily oxidized to soft graphite. The c-BN coating prevents oxidation. Diamond also interacts with iron, making it harder for steel tools." Again, c-BN will solve the problem. " c-BN is a cubic boron nitride (BN) with a cubic crystal structure. It has similar properties to diamond but has several advantages: c-BN has a high bandgap which makes it attractive for high-power devices; c-BN can be "doped" to have positive, Negative charge layer, which means that it can be used to make transistors; When exposed to oxygen, its surface forms a stable oxide layer, making it stable under high temperature conditions. Earlier this year, Narayan announced a faster, cheaper manufacturing of c-BN technology. The researchers first created the c-BN matrix to create epitaxial, or single-crystal diamond / c-BN structures. This uses the new technology Narayan released earlier this year. Diamond was then deposited on the c-BN surface using pulsed laser deposition at 500 ° C and optimized atmospheric pressure. The use of pulsed laser technology can control the thickness of the diamond layer. "It's all done in a single chamber and the process is more energy-efficient and time-sensitive," Narayan said. "Just use solid carbon and boron nitride, which is more environmentally friendly than traditional technology." Researchers were also able to deposit diamond on the c-BN surface using conventional CVD techniques, but this required the use of methane gas, hydrogen and a 900 ° C tungsten filament. "The chemical vapor deposition method can accomplish these tasks, but our pulsed laser deposition method works better, does not involve toxic gases and can be done at lower temperatures," Narayan said. Narayan has co-founded a company, q-carbon LLC. The company owns the technology and is committed to commercializing the technology in multiple applications.