Two-dimensional (2D) transition metal dichalcogenides (TMDs) have emerged as a versatile class of materials with tunable optical, electronic, and mechanical properties, enabling a wide range of optoelectronic and quantum device applications. Many TMDs exhibit multiple structural phases, each with distinct properties. Among them, MoTe₂ is particularly attractive due to its stable semiconducting 2H phase (hexagonal lattice) and metallic 1T′ phase (orthorhombic lattice), and the ability to transition between these phases reversibly. Traditional phase-transition techniques—such as thermal annealing, chemical doping, strain engineering, or laser ablation—often lack spatial precision and risk damaging the material.

In this work, we demonstrate a highly controlled method for inducing localized phase transitions using the NanoFrazor's laser-patterning capabilities, a commercial thermal scanning probe lithography instrument. We patterned 4 × 4 µm² regions using a 405 nm laser and observed a clear 2H-to-1T′ transition at a power of 53 mW with exposure times between 240 and 540 µs per pixel. Importantly, we differentiate true phase transitions from previously misinterpreted tellurium clustering and ablation events by combining Raman spectroscopy with nano-Auger electron spectroscopy. Our results show that excessive laser power or longer exposure times lead to significant Raman peak shifts associated with Te clustering, as confirmed by elemental mapping.

The NanoFrazor’s ability to deliver precise, customizable thermal energy enables deterministic nanoscale phase engineering with minimal material damage. This approach paves the way for creating coexisting hetero-phase junctions within a single 2D crystal, offering new possibilities for reconfigurable quantum, optoelectronic, and nanoscale device architectures.

Biography

Amirhossein Hasani is a scientist and process engineer with extensive expertise in semiconductor fabrication, nanofabrication, and advanced materials characterization. He earned his Ph.D. in Chemical Engineering and Materials Science in South Korea. At the MonArk NSF Quantum Foundry, he spearheads the development of quantum device pipelines, optimizing processes such as lithography and nanofabrication. His work integrates material synthesis with device fabrication to enhance performance and yield. With experience collaborating with foundries, mentoring researchers, and establishing infrastructure, Dr. Hasani bridges academic research and industry needs, driving innovation in advanced semiconductor technologies and next-generation quantum materials.