1. 연수기간 : 2021. 12. 06 ~ 2021. 12. 10 (총 4박 5일)
2. 연수국가 : Jeju, Korea
3. 연수기관명 : KPS (The Korean Physical Society)
4. 연수자 : 신진인력 연구교원
5. 연수주제 :
Controllable Surface Oxidation and Doping Effect of InSe Using Polymer Passivation
InSe, one of the van der Wald crystal structures, is a metal chalcogenide III-VI compound that can be exfoliated and has stable semiconductor properties. It has attracted considerable attention due to its low effective electron mass (0.14M), direct bandgap in bulk form (1.26 eV), and high charge mobility (300cm2/Vs). However, unlike TMDC, it is susceptible to moisture, so when exposed to air, it gradually oxidizes and degrades the device's performance. In an effort to overcome this, passivation is attempted using PMMA or h-BN, but the oxidation that occurs on the InSe surface itself is still unresolved. In this study, we tried two different types of polymer doping to control the surface oxidation of InSe and improve the device's performance. First, Benzyl Viologen (BV) as an n-type dopant injects electrons into the InSe layer to improve charge mobility. A CYTOP used as a p-type dopant injects holes, resulting in a p-doping effect. To confirm that these two types of polymers act as a passivation to prevent oxidation of the InSe surface, the polymers were covered the surface of the InSe FET. Then, the electrical characteristics of the InSe according to the concentration of the polymer were measured. This study makes the development of high-performance InSe devices useful by controlling InSe surface oxidation with polymers.
Controllable synthesis of topological semimetal PtTe2 and MoTe2 using laser and sputter for optoelectronic device
Topological semimetals, new topological materials, are being actively studied due to their unique electronic states. The opological semimetals have band touching points or lines on the Fermi energy, and their electronic states show stable surface states and interesting bulk phase responses. Although new topological semimetals have recently been theoretically predicted and confirmed experimentally, their direct synthesis has rarely been studied. In this study, a topological semimetal was directly synthesized using a laser, and an optoelectronic device with an ideal junction was fabricated. First, a large-area Te and Pt (Mo) thin film were deposited by a sputtering method. Then the phase transition to PtTe2 (MoTe2) from Te depending on the laser irradiation time was confirmed using Raman scattering measurement. The properties of PtTe2/PtTe2 devices synthesized directly with a laser were measured and compared with those made by exfoliation. This study presents a novel strategy for directly synthesizing optoelectronic devices based on various topological metalloid compounds.