Researchers develop world's first functional graphene semiconductor

This means that after 10 years of research, researchers say they have finally created the world's first functional semiconductor based on graphene. This will prove to help both quantum and conventional computing and keep Moore's Law alive.

According to Walt de Heer, a professor in the Department of Physics at Georgia Institute of Technology, electrons move 10 times faster than traditional silicon transistors. This exponential improvement means that it is possible for chips using graphene to reach cycles in the terahertz range.

The process for producing graphene is half a century old. First, two silicon carbide chips are stacked in a graphite crucible and then placed into an argon quartz tube wrapped with a copper tube. A high-frequency current is passed through the copper coil and the graphite crucible is heated to 1000°C through induction for about one hour.

After the silicon on the surface of the silicon carbide chip evaporates, it is replaced by carbon, forming a two-dimensional (single-atom) graphene layer. The produced wafers are charge-neutral, so they are immediately doped with oxygen when removed from the tube. They then produced epigraphene on a silicon carbide substrate by heating the graphene to 200°C in a vacuum to release the oxygen doping. According to deHeer, the cost of this process is relatively low.

"The (silicon carbide) chip we use costs about $10, the crucible costs about $1, and the quartz tube costs about $10," the professor explained to IEEESpectrum.

Since 2008, scientists have produced semiconductor graphene by heating silicon carbide in a vacuum. However, it lacks a measurable bandgap, so the transistor cannot turn on and off. DeHeer and his team's modified method eliminates this problem.

Previous methods of creating band gaps have been to modify substrates with graphene nanoribbons or nanotubes. None of these methods have been successful because they require high precision in depositing graphene nanoribbons on a substrate.

"There have been some successes with graphene nanoribbons, but in principle this technology is very similar to semiconducting carbon nanotube technology, which has yet to succeed after 30 years of nanotube research," deHeer said.

Researchers have had some success creating band gaps by deforming (wrinkling) graphene. However, this method produces a band gap of only 0.2 electron volts, which deHeer believes is too small to be practical. In comparison, silicon has a band gap of 1.12 electron volts. Georgia Tech's method produces a band gap of 0.6 electron volts, enough to enable logic switching at lower temperatures.