The researchers grew the nanomaterial in layers. By varying the thickness of each layer, said assistant professor Davood Shahrjerdi, the size and type of energy band structure could be tuned, in turn affecting the properties of the material.
“At monolayer thickness, this material has the optical properties of a semiconductor that emits light, but at multilayer, the properties change, and the material no longer emits light. This property is unique to this material.” By tuning the material growth process, the resulting thin film is speckled with randomly occurring regions that alternately emit or do not emit light. When exposed to light, this pattern translates into a one-of-a-kind authentication key that could secure hardware components at minimal cost.
The work represents the first physically unclonable security primitive created using MoS2. The team believes similar nanomaterial-based security primitives could be produced inexpensively at scale and applied to a chip or other hardware component. “No metal contacts are required and production could take place independently of the chip fabrication process,” Shahrjerdi said. “It’s maximum security with minimal investment.”