High-quality two-dimensional tellurium nanoflakes: synthesis and characterization

Abstract

Two-dimensional (2D) tellurium nanoflakes have attracted extensive attention due to their unique properties, yet controlling their highly anisotropic growth remains a significant challenge. In this study, we successfully synthesized highquality 2D tellurium nanoflakes via precise regulation of source zone temperature, substrate zone temperature and growth time. The results reveal that the source zone temperature primarily dominate the precursor vapor pressure; increasing it from 550 °C to 700 °C drives the evolution from discrete nuclei to well-defined 2D polygonal nanoflakes, enlarging the lateral dimensions up to ~50 μm. Conversely, the substrate zone temperature governs surface atomic diffusion and migration kinetics. Raising the substrate zone temperature from 400 °C to 600 °C triggers a distinct morphological transition from equiaxed polygonal nanoflakes to high-aspect-ratio one-dimensional (1D) nanoribbons (reaching ~120 μm in length). This behavior is ascribed to enhanced preferential longitudinal growth coupled with the evaporation-induced lateral contraction of basal-plane atoms. Time-dependent studies identify 1200 s as the optimal growth time. Prolonged durations exacerbate thermal decomposition due to the large specific surface area of the nanoflakes, leading to a sharp reduction in flake size and a shift toward nucleation competition. The high-quality Te nanoflakes developed in this work establish a critical material basis for the rational design and engineering of advanced Te-based electronic and optoelectronic devices.