Direct Selective Epitaxy of 2D Sb 2 Te 3 onto Monolayer WS 2 for Vertical p-n Heterojunction Photodetectors.

Two-dimensional transition metal dichalcogenides (2D-TMDs) possess appropriate bandgaps and interact via van der Waals (vdW) forces between layers, effectively overcoming lattice compatibility challenges inherent in traditional heterojunctions. This property facilitates the creation of heterojunctions with customizable bandgap alignments. However, the prevailing method for creating heterojunctions with 2D-TMDs relies on the low-efficiency technique of mechanical exfoliation. Sb 2 Te 3 , recognized as a notable p-type semiconductor, emerges as a versatile component for constructing diverse vertical p-n heterostructures with 2D-TMDs. This study presents the successful large-scale deposition of 2D Sb 2 Te 3 onto inert mica substrates, providing valuable insights into the integration of Sb 2 Te 3 with 2D-TMDs to form heterostructures. Building upon this initial advancement, a precise epitaxial growth method for Sb 2 Te 3 on pre-existing WS 2 surfaces on SiO 2 /Si substrates is achieved through a two-step chemical vapor deposition process, resulting in the formation of Sb 2 Te 3 /WS 2 heterojunctions. Finally, the development of 2D Sb 2 Te 3 /WS 2 optoelectronic devices is accomplished, showing rapid response times, with a rise/decay time of 305 μs/503 μs, respectively.