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.