"Graphene is conductive, but is not a semiconductor; graphene oxide has a bandgap like a semiconductor, but does not conduct well at all – so we created rGO," says Professor Jay Narayan. "But rGO is p-type, and we needed to find a way to make n-type rGO. And now we have it for next-generation, 2D electronic devices."
According to the scientists, they could integrate rGO onto sapphire and silicon wafers.
The researchers used high-powered laser pulses to disrupt chemical groups at regular intervals across the wafer. This disruption moved electrons from one group to another, converting p-type rGO to n-type rGO.
The entire process is said to have taken place at room temperature and pressure, using high power nanosecond laser pulses, and was completed in less than one-fifth of a microsecond. The laser radiation annealing provides a high degree of spatial and depth control for creating the n-type regions needed to create p-n junction-based 2D electronic devices.
The end result is a wafer with a layer of n-type rGO on the surface and a layer of p-type rGO underneath. This is said to be critical because the p-n junction is what makes the material useful for transistor applications.