Studies of Novel 2D Materials Based Devices and their Encapsulation

Abstract

Two dimensional (2D) materials, such as graphene and transition metal dichalcogenides (TMDs), are at the forefront of next generation electronic and optoelectronic technologies due to their atomic scale thickness, exceptional carrier mobility, and tuneable physical properties. Their applicability in flexible electronics, high speed transistors, sensors, and quantum devices is well established. However, their monolayer structure makes them highly sensitive to environmental interactions, including substrate effects and atmospheric doping, which can degrade device performance by introducing charge inhomogeneities and mechanical strain. To address these challenges, this thesis investigates soy wax as a non-invasive encapsulation. Raman spectroscopy demonstrates that soy wax encapsulation significantly enhances the structural uniformity of graphene, narrowing and centring the distributions strain and doping. Strain levels stabilize around 0.5%, while doping concentrations converge near 0.20 × 10¹³ cm⁻². These findings indicate a reduced charge inhomogeneity and mechanical distortion, contributing to improved carrier mobility and a more stable electronic environment. In parallel, this thesis explores the structural characteristics of emerging 2D TMDs such as ReS₂, WTe₂, and In₂Se₃ which hold significant potential for nanoelectronics and optoelectronic applications. ReS₂ exhibits in-plane anisotropy, WTe₂ shows topological and magneto-resistive behaviour, and In₂Se₃ possesses intrinsic ferroelectricity. Raman spectroscopy enabled precise estimation of the number layers through characteristic vibrational modes, while atomic force microscopy (AFM) provided detailed measurements of surface roughness and step heights, confirming thickness and uniformity. Together, these complementary techniques enabled a thorough assessment of material quality, which is crucial for reliable device integration. Overall, the findings underscore the importance of encapsulation strategies and high resolution structural characterization in enhancing the performance and scalability of graphene and other 2D materials for advanced electronic applications