The material, technically known as hexagonal boron nitride, features better transparency than its sister, graphene, is chemically inert, or non-reactive, and atomically smooth. It also features high mechanical strength and thermal conductivity. Unlike graphene, however, it is an insulator instead of a conductor of electricity, making it useful as a substrate and the foundation for the electronics in cell phones, laptops, tablets and many other devices.
Growth and transfer of 2-D material such as hexagonal boron nitride and graphene was performed by a team that included Yijing Stehle of Oak Ridge National Laboratory. Credit: ORNL
“Imagine batteries, capacitors, solar cells, video screens and fuel cells as thin as a piece of paper,” said ORNL’s Yijing Stehle. She and colleagues are also working on a graphene hexagonal boron 2D capacitor and fuel cell prototype that are not only “super thin” but also transparent. With their recipe for white graphene, ORNL researchers hope to unleash the full potential of graphene, which has not delivered performance consistent with its theoretical value. With white graphene as a substrate, researchers believe they can help solve the problem while further reducing the thickness and increasing the flexibility of electronic devices.
While graphene, which is stronger and stiffer than carbon fiber, is a promising material for data transfer devices, graphene on a white graphene substrate features several 1000X’s higher electron mobility than graphene on other substrates. That feature could enable data transfers that are much faster than what is available today. “Imagine your message being sent thousands of times faster,” Stehle said.
Stehle noted that this work is especially significant because it takes the material beyond theory. A recent theoretical study led by Rice University, for instance, proposed the use of white graphene to cool electronics. Stehle and colleagues have made high-quality layers of hexagonal boron nitride they believe can be cost-effectively scaled up to large production volumes. That process consists of standard atmospheric pressure chemical vapor deposition with a similar furnace, temperature and time, but there’s a twist… “a more gentle, controllable way to release the reactant into the furnace and figuring out how to take advantage of inner furnace conditions. These two factors are almost always neglected.”
https://www.ornl.gov/news/ornl-process-could-be-white-lightning-electronics-industry
Here we investigate the growth stages of the hBN single crystals and show that hBN crystals change their shape from triangular to truncated triangular and further to hexagonal depending on copper substrate distance from the precursor. We suggest that the observed hBN crystal shape variation is affected by the ratio of boron to nitrogen active species concentrations on the copper surface inside the CVD reactor. Strong temperature dependence reveals the activation energies for the hBN nucleation process of ∼5 eV and crystal growth of ∼3.5 eV. We also show that the resulting h-BN film morphology is strongly affected by the heating method of borazane precursor and the buffer gas.
Recent Comments