Russia confirms diamond shows presence of NaCl film as gate insulating layer for field effect transistors

According to foreign media reports, Russia’s Skolkovo Institute of Science and Technology (Skoltech) and Moscow Institute of Physics and Technology (MIPT) first predicted, and then tested, confirmed the existence of a strange NaCl film on the surface of diamond. Can be used as a gate insulating layer for field effect transistors in electric vehicles and telecommunication equipment.

(Image credit: Skoltech)

Skoltech doctoral students Kseniya Tikhomirova, Dr. Alexander Kvashnin, and Skoltech and MIPT professor Artem R. Oganov, in collaboration with colleagues, based on earlier studies of NaCl films, hypothesized that an unusual, nanometer-thick NaCl film also exists on the surface of diamond.

Kseniya Tikhomirova said: “In the beginning, we decided to only perform computational studies on the formation of novel 2D structures on different substrates, assuming that if the substrate interacts strongly with the NaCl film, major changes in the structure of the film can be predicted. Facts We got very interesting results and predicted the formation of hexagonal NaCl films on diamond substrates, and then decided to conduct experiments. After experiments, hexagonal NaCl films were synthesized, which confirmed our theory.”

The researchers first employed the evolutionary algorithm USPEX, developed by Oganov and his students, to predict the lowest-energy structure based on the chemical elements involved. Experimental synthesis and characterization using XRD (X-ray Diffraction) and SAED (Selected Area Electron Diffraction) measurements confirmed the existence of NaCl films. The average thickness of the film is about 6 nanometers, and thicker films turn the hexagonal structure into a cubic structure, the familiar typical structure of table salt.

Scientists believe that the hexagonal NaCl film is very suitable for use as a gate insulating layer in diamond field-effect transistors due to its strong adhesion to the diamond substrate and wide energy bandgap. potential in telecommunications equipment. Today, hexagonal boron nitride is commonly used in such field-effect transistors, which has a similar bandgap width to the film, but has weaker adhesion to the substrate.

The research provides a better understanding of how to control the appearance and properties of 2D materials that use substrates, and opens the door to more 2D materials with potential applications in electronics and other fields.

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