Integration of two-dimensional materials with self-assembled structure arrays for modifying electrical/optical properties

Abstract

Recent studies on two-dimensional (2D) materials have shown great promise in the areas of both fundamental physics and potential applications. Among these studies, some have targeted the possibility of potentially replacing Si with 2D semiconducting materials due to their inherent flexibility, high transparency, and excellent carrier transport properties. Although the materials have many benefits that bulk cannot do, several issues are remained, especially its property modification that is important for various application field. In Chapter 2, I will describe a reliable and universal doping route for few-layer TMDs by employing surface-shielding nanostructures during a plasma-doping process. By locally blocking strategy, I could obtain electrical property modification applied to n- or p-type using various plasma source. Here, I achieved controlling of the n-doping level of few-layer MoS2 via the local generation of extra sulfur vacancies without compromising the carrier mobility. In Chapter 3, I will describe a new strategy based on the insertion of high-density topographic nanopatterns as a high-frequency supporter between 2D materials and substrate to minimize their contact and to block the substrate-induced undesirable effects. To engineer the substrate geometry, the most prominent factor is naturally optimized using self-assembled nanostructures based on competition of (i) strain energy of film and (ii) sum of attractive energies. By utilizing ultimately short period of nano-supporter, stably suspended architecture accompany with performance enhancement was achieved. In Chapter 4, I will describe a highly effective spacer material for atomically thin materials. I integrated plasmonic structures, 2D materials, and self-assembled gap spacer to achieve minimized field decay that is reaching 2D materials, I utilized NHS structures as an expanded manners for low n and ε spacer. Based on the integrated hybrid structures with monolayer MoS2 on NHS and ARA, PL intensity of MoS2 is drastically enhanced for ~ 6.3 times with elimination of charge transfer between both materials. By employment of self-assembled block copolymer patterns, and integration with two-dimensional materials, it is promising era based on its simplicity of processing and effectiveness on performance enhancement. Therefore, usage of BCP would be expandable for various low-dimensional applications fields.