Laser Thinning of Silica Nano Composite Coated 2H MoTe2

Abstract

Transition metal chalcogenide (TMD) is a material that can change band gap characteristics and size according to thickness adjustment [1-5]. To take advantage of these properties, various research methods have been developed to obtain atomically thin layers of TMD material [6-8]. In particular, research on the structural change and phase transition of TMD by laser irradiation is drawing attention [9-13]. However, structural manipulation using laser irradiation in transition metal chalcogenide compounds can cause problems such as sample defects and oxide formation. In this study, a silica nanocomposite material (SNC) coating with excellent heat resistance and oxidation resistance was used to address this issue. Furthermore, experiments were conducted to determine whether the SNC coating could play a role in protecting the surface of the TMD. SNC coating was applied to 2H-MoTe2 flakes deposited on SiO2/Si substrates. At the same time, by optimizing the SNC coating conditions and understanding their role, we propose the possibility of using SNC coating as a capping material through a laser irradiation method using SNC coating. Currently, transition metal dichalcogenide (TMD) is receiving a lot of attention as a next-generation semiconductor device. In particular, laser thinning of two-dimensional TMDs has been regarded as an effective way to precisely control thickness to modify the bandgap of TMDs. However, laser thinning has caused difficulties in the study of nanoscale TMD materials due to structural changes and changes in physical and chemical properties due to high thermal energy. In this study, laser thinning was performed by coating 2H MoTe2 with a film having heat resistance and oxidation resistance. Although an unexpected 1T' phase transition occurred during the previous laser thinning process, it was confirmed that MoTe2 coated with silica-nanocomposite still maintains a 2H structure within the crystal. This confirmed that the laser thinning method through silica nanocomposite coating has different properties from the conventional thinning process. This study suggests the possibility that the laser thinning method using silica nanocomposite coating can be utilized to produce TMD materials with fewer layers while preserving the original crystal structure.;2차원 층상 물질인 전이금속 디칼코제나이드 (TMDs)는 두께 조절에 따라 밴드갭 특성과 크기를 변경할 수 있다. 이에, 이러한 특성을 활용하기 위해 원자적으로 얇은 층상 TMD 물질을 얻기 위한 다양한 방법들이 연구되어 왔다. 특히 레이저 조사에 의한 TMD의 박형화와 상전이에 대한 연구가 활발히 연구되고 있다. 그러나, 전이금속 디칼코제나이드 화합물의 박형화를 위한 레이저 조사는 시료의 결함, 산화물 형성 등의 문제가 발생할 수 있다. 본 연구에서는 레이저 노출시 텔루륨 공실이 예기치 않게 형성되는 것을 방지하기 위해 내열성과 내 산화성이 우수한 Silica-Nanocomposite을 코팅 소재로 사용하였다. 이는 레이저 출력과 레이저 노출 시간을 효율적으로 끌어 올리고, 시료의 손상을 막았다. 동시에 1T’상이 남는 기존의 솎아내기 방법과는 달리 박형화의 마무리에서 2H상만 남는 것을 확인했다. 우리는 내열성과 내산화성을 가진 실리카 나노 복합 코팅을 사용한 레이저 박형법을 적용하여, 원래의 결정구조를 보존하고, 원자 수준 두께의 TMD 재료의 생산에 활용할 수 있음을 보이는 연구를 수행하였다.