Universal tellurization-mediated buffer layer strategy derived from substrate-induced decomposition for large-area...

Atomically thin two-dimensional (2D) materials possess a wide range of remarkable properties, making them promising candidates for the development of next-generation electronic and optoelectronic devices. Among the 2D materials, bulk PbTe exhibited topological properties, which show its potential in developing topological quantum computing devices, but its size drowned out its hidden excellent properties. Here, we demonstrated a tellurization-mediated buffer layer strategy for fabricating large-area PbTe monolayers on Ag(111), Cu(111), and Au(111) substrates, involving sequential decomposition, tellurization, and epitaxy steps. Substrates catalyze PbTe molecular dissociation into Pb and Te atoms; Te atoms then react with substrates to form AgTe, CuTe, or Au-Te buffer layers, which suppress further PbTe decomposition and enable epitaxial growth of high-quality PbTe monolayers with well-defined tetragonal lattices. Scanning tunneling microscopy measurements have revealed that the buffer layer-supported PbTe monolayers exhibit an apparent height of 2 Å and a lattice constant of 0.8 nm. Notably, PbTe monolayers exhibit moiré superstructures with distinct periodicities on AgTe and CuTe buffer layers, due to differences in buffer layer symmetry and lattice parameters. Scanning tunneling spectroscopy measurements further demonstrate that the PbTe monolayer on the AgTe buffer layer possesses a bandgap of 2.3 eV, which is significantly larger than that of bulk PbTe. Our study provides critical strategies for the controlled synthesis of PbTe monolayers, laying a foundation for their atomic-scale applications.