Using a "photo-doping" process, Michigan State University scientists changed the electronic properties of materials in a way that more easily allows an electrical current to pass through. By shooting an ultrafast laser pulse into the material, the properties change and appear chemically “doped.” The method has potential applications that could lead to the development of next-generation electronic materials, as well as optically controlled switching devices.

The unconventional semiconductor material is made of alternating atomically thin layers of metals and insulators. The combination allows unusual properties, including highly resistive and superconducting behaviors, to emerge.

The ultrafast electron-based imaging technique developed by associate professor Chong-Yu Ruan and his MSU engineers enabled the group to observe the changes in the materials. By varying the wavelengths and intensities of the laser pulses, the researchers observed phases with different properties, captured on the femtosecond timescale.

The laser pulses act like dopants that temporarily weaken the glue that binds charges and ions together in the materials. Electronic phases spontaneously form to engineer new properties in the materials.