American scientists have developed a method to study changes in the structure of polycrystalline films of transition metal disulfides under the action of electric current using transmission electron microscopy. For example, molybdenum disulfide, the authors found that the most important role in the destruction of the film played by voids at grain boundaries, which grow due to the migration of atoms of molybdenum and sulfur. The results of a study published in the journal ACS Nano.
Two-dimensional semiconductors such as graphene and boron nitride, have a great potential for application in electronic devices of new generation. In recent years, to create a more stable semiconductor materials with the desired electrical, optical and catalytic properties of the synthesized layered structures of the dichalcogenides
transition metals with specified defects. For example, the electrical properties of grain boundaries dichalcogenides, obtained in the gas phase, different from the rest of the framework and depend on the angle of the grain boundaries. Recent studies have shown that these boundaries are in the process of operation of the device is stronger than heat up and oxidize, which reduces the service life of the material. Similar phenomena explain the presence of nanopores and vacancies of s atoms in the film.
To explore dependency properties from dynamic changes in the structure of the layers through the material flow the electric current with the help of transmission electron microscope to monitor the change in the electrical response of the material depending on Nanophysics phenomena in the structure of the material. Such experiments are technically difficult to implement, therefore, studies of single-layer structures of transition metal dichalcogenides using this method not so much.
Akshay Murthy (Murthy Akshay A.) with colleagues from northwestern University have developed a technique of synthesis and examination of changes in the structure of polycrystalline films single layer of molybdenum disulfide under the influence of the bias current by transmission electron microscopy. Scientists put silicon on quartz microscope grid electrodes made of gold at a distance of one micron from each other and moved them polycrystalline single-layer film of molybdenum disulphide between pairs of electrodes, which then connected the wires.