Multilayer Band Gap Discovered by DGIST Team Using Own Tech

Dr. Hyunmin Kim’s team in the Companion Diagnostics and Medical Technology Research Group and Professor Jae-dong Lee’s team in the department of Emerging Materials Science at DGIST proved the presence of upper band gap of atomic rhenium disulfide (ReS2) layers in the conductive atomic structure of ionization energy, through a collaborative research with Professor Jong-hyun Ahn’s research team at Yonsei University.

A recent work by Dr. Hyunmin Kim (Left) and Professor Jaedong Lee (Right) at DGIST unveiled the existence of the second band gap in a 2D structure. (Image credit: DGIST)

Even the scientific community has only theoretically predicted the ionization energy area of 2D atomic structures and has had problems in establishing the actual existence of structure. However, Professor Hyunmin Kim’s research team at DGIST could see the actual structure using “time-resolved second harmonic generation (TSHG) imaging system” it created, establishing the existence of disulfide band gap layers.

The “time-resolved second harmonic generation imaging system” can produce the images of the sounds of atomic-layered structure in 300 nm of high-resolution, playing a vital role in making the study successful. This system boosted the sensitivity of measuring the dispersion effects of layer noise and witnessed electron movements inside transition bands, which are visible rays and near-ultraviolet rays using the probing energy of infrared bandwidth.

Through this research, we will be able to clarify the structure of multilayer band gaps existing in various atopic structures besides the rhenium disulfide that was observed this time. It provided important elements to analyze the unidentified causes of electronic activities which contribute to driving the optical sensors and photocatalysts of various 2D structures. In the future, I hope to develop a device that operates both optically and electrically by a new band gap.

Dr. Hyunmin Kim, Senior Researcher, Companion Diagnostics and Medical Technology Research Group, DGIST

Furthermore, Professor Lee, who calculated the theories of research, said: “We could observe multi-layer bandgaps in this research, which will greatly help with related researches such as observing band gaps of junction structures and improving device agglomeration in the future.”

This research has been published online on Light: Science and Application, on November 28, 2018, a sister magazine in optical science of well-known academic journal Nature.

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