Professor Young-Dahl Jho's research team identifies elastic and thermal properties of free-standing molybdenum disulfide membranes
□ A research team led by Professor Youn-Dahl Jho of the School of Electrical Engineering and Computer Science at the Gwangju Institute of Science and Technology (GIST, President Seung Hyeon Moon) has experimentally investigated the heat transfer characteristics in two-dimensional molybdenum disulfide membranes (molybdenum disulfide, MoS2 *).
* Two-dimensional molybdenum disulphide (MoS2): An inorganic compound consisting of molybdenum, which is a member of transition-metal dichalcogenide family on the periodic table. Recently, research has focused on its unique electronic and thermoelectric properties.
□ Molybdenum disulfide, a transition metal, has high electron mobility and thermoelectric properties that can improve heat dissipation and transfer characteristics of existing electronic and thermoelectric devices, thereby prolonging the life of the device while improving efficiency.
∘ In order to utilize new two-dimensional materials such as molybdenum disulfide for electronic devices, it is necessary to study its thermal properties, such as the speed of acoustic phonon, which plays an important role in thermal conductivity and heat transfer in a thin-film structure. However, measuring the acoustic phonon velocity has never been done before this research. Therefore, this research will play an important role in experimentally understanding the theoretical speed and heat transfer characteristics of in-plane acoustic phonons.
□ According to the researchers, ultrafast transient grating spectroscopy *, which uses a laser interferometer to create a thermal grating in which the amount of heat is periodically controlled, was first introduced into the two-dimensional nanomaterials.
* Ultrafast transient grating spectroscopy: A spectroscopic method to measure the transfer characteristics of quasiparticles generated in a solid by using the interference of two laser beams.
∘ Ultra-fast grating diffraction spectroscopy is expected to be applied to various 2D nanomaterials as an ultra-fast way to observe the generation and transmission of heat in nanomaterials while avoiding electrical or thermal contact.
∘ Since heat is mainly transmitted in the form of atomic vibrations *, the heat removal efficiency can be improved by understanding the characteristics of atomic vibrations involved. Professor Young-Dahl Jho's research team experimentally observed the atomic oscillation propagation velocity in view of the fact that the atomic oscillation frequency and the size of the lattice occur before the thermal grating disappears, which is proportional to the atomic oscillation velocity.
* Atomic vibrations: quantized oscillations in which the interatomic distance in the crystal structure varies with time. Acoustic phonons play an important role in the thermal conductivity of solids.
□ Professor Young-Dahl Jho said, "Through this research, we will understand the characteristics of heat in two-dimensional nanomaterials and utilize it to remove heat from electronic devices."
