St. Petersburg State University
The mechanics of thin film materials.
Thin film materials range from hundreds of nanometers down to only a few nanometers in thickness. To put this size-scale in perspective, a bacterial cell is about 500 nanometers thick. Recently attention has been focused on the development and investigation of thin film materials because they are able to provide performance improvements in the properties of mechanical, thermal, optical, electrical, magnetic, chemical and even biological products. Some applications include ultrahigh-density data storage, high-frequency components for wireless communications, and sensors for medical diagnostics. In fact, thin films represent major components in such advance areas like electronics, computers, optics, chemical and biological systems.
However, these benefits can only be achieved if defects in the thin film are kept to a minimum. Analyzing patterns in thin films, it was found that even slight variations in the surface consistency could lead to cracks and splitting of the film layers. Interestingly, neither is the goal to obtain absolute uniformity, as limited variations in the surface impart benefits to the material. Therefore, accurate control of thin film surface character is needed to improve manufacturing techniques. To obtain such a level of control we need to simulate this process computationally to gain a better theoretical understanding.
How to do this? Should we take into account the atomic structure of the film or instead consider the average properties of material? While atomistic simulations provide more proper description of behavior, there is an important limitation related to computational power. Even super-computers are not up to the task. At the opposite extreme crude models based on the average properties of the bulk material do not predict behavior at the nanometer scale accurately. Thus, a main current challenge in thin film science is the development of more efficient simulations that take advantage of both bulk- and atom-level calculations to provide a better understanding of thin film production and ease the development of cutting edge materials.