Laser-Based Synthesis of Low-Dimensional Materials

Abstract

Materials are critical for the advancement of modern technology, as the performance, reliability, and functionality, especially of electrical systems and devices, are greatly governed by the properties of materials. Continuous advancement in materials such as conductors and semiconductors have enabled the development of fast, miniature, energy-efficient, and high-performance technologies. In recent years, there has been a growing demand for low-dimensional and functional materials to power the next generation of electronic, photonic, quantum, and sensor technologies. Low-dimensional materials (LDMs) are materials in which at least one dimension is confined to the nanoscale, and the properties of these materials are strongly influenced by their size and shape, giving rise to physical properties distinct from those of their bulk counterparts. Engineering materials at the nanoscale, and thereby obtaining materials with a high specific surface area and enhanced mechanical, electrical, and optical properties, has opened new and promising avenues for research. Among low-dimensional materials, two-dimensional (2D) transition metal dichalcogenides (TMDCs) have emerged as promising building blocks for next-generation electronic, photonic, and quantum devices. Despite their significant potential, conventional methods for synthesizing these materials often rely on multiple precursors, complex chemistry, high-temperature processing, and toxic environments, limiting the growth of stoichiometric crystals, wafer-scale uniformity, and substrate compatibility. To address these challenges, this dissertation presents laser-based materials processing as a unified platform for scalable materials synthesis, interface engineering, device integration, and additive nanomanufacturing. At the core of this unified platform is a laser-based growth approach based on the pulsed laser deposition (PLD) process for the wafer-scale growth of two-dimensional (2D) materials. Conventional PLD techniques for synthesizing two-dimensional materials often encounter significant challenges arising from the high volatility and low vaporization temperatures of chalcogen atoms. To address these limitations, this research employed a novel amorphous phase-mediated crystallization (APMC) strategy for the wafer-scale synthesis of 2D materials. The approach involves room-temperature PLD to deposit amorphous precursor layers with precisely controlled thickness, followed by a post-deposition annealing step that transforms the amorphous films into crystalline structures, thereby preserving the material stoichiometry. The laser-synthesized 2D materials were subsequently integrated into wafer-scale devices using conventional photolithography, demonstrating compatibility with established semiconductor fabrication processes. The laser-based platform was further extended to interface engineering through the synthesis and substrate-dependent optical analysis of single-crystalline monolayer 2D materials. A laser-assisted synthesis technique was employed to synthesize high-quality single-crystalline monolayer 2D materials from stoichiometric precursors. The synthesized films were subsequently transferred onto interdigitated Si–Si/SiO2 platforms to examine the influence of bare Si and Si/SiO2 surfaces on these 2D TMDC materials. Strong evidence of Raman and photoluminescence (PL) quenching due to the optical interference, charge transfer, dielectric screening, and surface interactions between the 2D thin film and the substrate was observed. Our findings highlight the potential of substrate engineering to tune the optoelectronic performance of 2D materials for advanced device applications, thereby opening new perspectives in microelectronics. Building on the preceding studies of laser-based TMDC synthesis and processing, this work extended the laser-based platform to dry additive nanomanufacturing through the direct printing of two-dimensional transition-metal dichalcogenides on rigid and flexible substrates. The same approach was subsequently used to fabricate interdigitated silver electrodes on biodegradable paper substrates for capacitance-based humidity and resistance-based temperature sensors. The fabricated devices operated reliably across 20–90% relative humidity and 25–50 °C, demonstrating the compatibility of laser-enabled dry printing with flexible, low-cost, and environmentally sustainable paper-based electronics. In summary, this dissertation establishes laser-based materials processing as an integrated pathway from material synthesis and structural control to interface engineering, device integration, and additive nanomanufacturing. Together, the APMC growth, wafer-scale fabrication, substrate engineering, and dry printing studies form a unified framework for scalable microelectronics, optoelectronics, and sustainable sensing technologies.