Scientists from Tomsk Polytechnic University and their colleagues from Germany have demonstrated the behavior of areas of 2D materials which are applied in advanced electronics. Their findings could be used for the creation of flexible displays for smartphones, smart devices, flexible optical and computing schemes, flexible solar cells, and more.
According to the study authors, these experiments have not been conducted before. The scientists are working on a technology that allows users to see how materials interact at the nanoscale level to determine local strain occurring at their interaction and even to see defects in the materials at the nanoscale that will make it possible to improve nanoelectronic components.
A schematic of the experiment.(Source: Tomsk Polytechnic University)
“Now in the field of electronics and digital technology, there is a trend to miniaturize the devices. This trend is most relevant for transistors,” says Prof. Raul Rodrigez from the Department of Lasers and Lighting Technology. “Nowadays there are modern technologies which enable the creation of transistors with a channel width of 12 to 14 nanometers, thus placing more transistors in the processor, increasing the productivity of smartphones and other miniature electronic devices. To further improve these technologies and create transistors of even smaller sizes, we should understand how the semiconductor material behaves when interacting with metals and how its properties change at the nanoscale.”
Earlier electronic component materials were studied only at the macro- and microscale, but data obtained was not always sufficient to understand the interaction of materials with each other. The scientists from TPU and Chemnitz Technological University, along with the University of Regensburg (Germany), demonstrated for the first time how component materials of advanced nanoelectronics behave at the nanoscale.
“For the creation of the complete line of different devices used in nanoelectronics, in particular, flexible ones, various classes of two-dimensional materials are required, including semiconductors. Molybdenum disulfide is one of the most famous semiconductors. Our goal was to study strain occurring in this material at the nanoscale, as well as the processes of its stretching or compressing in different structures and fields,” said the authors of this research.
The scientists used gold nanoparticles. Two monolayers of molybdenum disulphide were placed on top of the particles, which was transformed due to the convex shape of nanotriangles that caused a biaxial strain of 1.4%.
“The strain is more than we initially expected to see. In general, we had no goal to create the highest possible strain, but it's interesting that by simply putting thin layers of molybdenum disulfide on metal we may obtain such significant deformations. This is very important to understand what happens when a semiconductor (molybdenum disulfide) contacts a conductor (gold) if we want to create a nanodevice,'” said, Prof. Rodrigez. “In our work, we showed that we can't neglect the interaction between a thin film and a substrate in electron nanodevices. When these materials are studied, all their properties are investigated on a flat substrate. However, a metal used in electrodes may change the properties of the material. This is inevitable, but perhaps it can be used in a way,”
Rodrigez specifies that the published article was the first to describe local measurements of strain.
The experiment was a success due to a unique technology called Tip-Enhanced Raman Spectroscopy (TERS), combining methods of optical spectroscopy and atomic force microscopy. The main element of the technology is a gold nano-antenna embedded in an atomic-force microscope. The size varies from microns at the base to nanometers at the tip. A nanoparticle is placed on the tip of the antenna, and scientists study only signals received from this nanoparticle.
The scientists emphasize that the TERS method is applicable for studying local strain and interaction processes in a particle and detecting defects in certain materials at the nanoscale.
The paper on this research was published in NanoLetters.
