Light beams tune graphene transistors

A novel way has been found to tune graphene and other 2D material devices, by employing chiral light beams. A light beam induces strain on the layer of graphene, causing local mechanical deformation which in turn locally changes electrical properties of the device. Researchers have demonstrated control over the conductivity of graphene transistors, showcasing the potential for optical manipulation of future electronic devices.

A research article, published in the journal ACS Nano, makes use of Graphenea’s graphene field effect transistors (GFETs) and the Graphenea card, which enable facile use of graphene devices. The electrical properties of graphene are known to be highly dependent on strain induced by out-of-plane deformations, and conductivity measurements provide a direct measurement of the influence of strain, with wrinkles and rumples reducing the conductance. Illumination by laser light caused a decrease in conductance, but the decrease was much more significant when the light was structured to carry orbital angular momentum, which causes sheer strain on the graphene surface.

Image: Light beams cause strain in graphene. From ACS Nano 2024, 18, 31, 20401-20411, under CC BY 4.0.

Light-induced strain was also observed on monolayer WS2 (tungsten diselenide), a 2D semiconductor. The researchers monitored light-induced strain with optical methods in the case of WS2.

The research introduces optical strain engineering in 2D materials, as a novel method for manipulating electrical and optical properties of 2D devices. Potential applications include optical switching of electronic transistors, rotation of individual layers in 2D material heterostructures or bilayers, and optically writing and erasing electronic properties of 2D materials, for next-generation optoelectronic technologies.