Tellurium-Assisted Recrystallization of MoTe₂ for Improved Electronic and Optoelectronic Properties

Molybdenum ditelluride (MoTe₂) single crystals often exhibit poor phase control, high defect density, and unintended contamination during synthesis, significantly influencing their potential in applications and fundamental studies. Therefore, the high-quality growth of MoTe₂ crystals is crucial to understanding their inherent properties and using them for suitable applications. This study employs the self-flux technique to demonstrate a tellurium (Te)-driven two-step approach for synthesizing high-quality bulk MoTe₂ single crystals. High-quality MoTe₂-grown single crystals, obtained by using the self-flux method, exhibited unipolar n-type behavior with a controlled charge density achieved by adjusting the Te molar concentration during the two-step recrystallization growth process. These results are substantiated by detailed electrical charge transport measurements of MoTe₂-based field-effect transistors (FETs), showing the highest mobility of approximately 63.37 cm²/(V s) and an on/off ratio of 10⁵ compared to nonrecrystallized samples with a mobility of 32.85 cm²/(V s), representing a 92.91% improvement at room temperature. Additionally, high-quality MoTe₂ FETs demonstrated a remarkable photoresponse across the ultraviolet to near-infrared wavelength regions, confirming their utility for broadband optical communication. Our demonstration of the high-quality growth of MoTe₂ crystals highlights the importance of a two-step approach to recrystallization synthesis and its appropriate potential applications in electronics and optoelectronics for future integrated devices.