Thin film growth of 2D materials and microscopic investigation of thermoelectric and heusler compound

Abstract

Two-dimensional van der Waals (vdW) materials are a new class of material with immense possibility in the field of ultra-thin transistor, optoelectronic devices and various energy conversion related application [1-4]. Atomically thick 2D layered materials generated immense research interest since the discovery of graphene [3-4]. Due to zero band gap in Graphene the attention shifted towards MoS2, WS2, ReS2 belonging to the family known as layered transition metal dichalcogenides (TMDs) [3-6]. On the other hand, vdW heterostructures emerge as new class of advanced materials by stacking various combination of 2D materials either on top of each other (vertical heterostructure) or zipping at the edges (in-plane heterostructure) [7-8]. This provides an opportunity to tailor the property of such 2D materials beyond the expected opportunities. Coupled quantum wells (CQW) which is supposed to host indirect excitons may also be realized based on such heterostructure system [8]. However, most of the fundamental properties based on 2D-TMDs have been investigated based on mechanically exfoliated and chemically synthesized materials, where dimensions of materials are small and not suitable for the large area practical device fabrication. Therefore, many attempts have been made with various physical crystal growth techniques to grow such vdW materials epitaxially over large area [9-13]. In chapter 2 and 3 we describe the use of PLD growth technique to grow such 2D TMDs and their heterostructure over large area (55 mm2).