Stepping closer to transparent, flexible electronics with new calculation methods

Electronics that are transparent and flexible can be made using thin films of ferromagnetic materials, but creating thin films requires precise control over the number of layers during fabrication. Yonemori et al. developed a numerical method to predict how the Raman-spectroscopy signature of a ferromagnetic material changes with its layer thickness and structure.

The authors theoretically studied the electronic states and phonon modes of few-layer tin sulfide thin films, which have recently shown strong layer-number dependence on ferroelectricity. They found the out-of-plane vibration modes in the frequency range of 265 to 290 inverse centimeters yield different sets of characteristic Raman frequencies for the surface and bulk layers of the materials as the number of layers increase and the stacking between the layers changes.

Though the study focused on theoretical approaches, the team’s results may be useful in studying experimentally synthesized tin-sulfide thin films.

“The systematic studies of thickness dependence of Raman active mode for tin sulfide thin films are not provided so far from a theoretical point of view, which are needed for materials characterization,” co-author Katsunori Wakabayashi said.

The team used first-principles computations based on density functional theory to identify the properties of the tin sulfide thin films. This approach allowed the authors to remove any unwanted bias that could come from the environment in an experimental setting.

Wakabayashi said future work should focus on further understanding the electronic and optical properties of tin sulfide, and on synthesizing larger thin films, so they can be realistically used in future electronics.

Source: “Thickness-dependent Raman active modes of SnS thin films,” by Itsuki Yonemori, Sudipta Dutta, Kosuke Nagashio, and Katsunori Wakabayashi, AIP Advances (2021). The article can be accessed at https://doi.org/10.1063/5.0062857 .