Synthesis of Ultrathin Composition Graded Doped Lateral WSe₂/WS₂ Heterostructures

Abstract

Lateral transition-metal dichalcogenide and their heterostructures have attracted substantial attention, but there lacks a simple approach to produce large-scaled optoelectronic devices with graded composition. In particular, the incorporation of substitution and doping into heterostructure formation is rarely reported. Here, we demonstrate growth of a composition graded doped lateral WSe/WS heterostructure by ambient pressure chemical vapor deposition in a single heat cycle. Through Raman and photoluminescence spectroscopy, we demonstrate that the monolayer heterostructure exhibits a clear interface between two domains and a graded composition distribution in each domain. The coexistence of two distinct doping modes, i.e., interstitial and substitutional doping, was verified experimentally. A distinct three-stage growth mechanism consisting of nucleation, epitaxial growth, and substitution was proposed. Electrical transport measurements reveal that this lateral heterostructure has representative characteristics of a photodiodes. The optoelectronic device based on the lateral WSe/WS heterostructure shows improved photodetection performance in terms of a reasonable responsivity and a large photoactive area.

Recent Advances in 2D Lateral Heterostructures

“…Reprinted with permission from Ref. [130] of this heterostructure can also reach up to 15.2%. Above results confirm that WSe 2 -WS 2 heterostructures are proper elements for high-performance optoelectronic devices.…”

“…The rectification behaviors are influenced mainly by the side connection length between aGNR and zGNR. The different interface defects cause the asymmetrical transmission of electrons and holes, which S/S type II [130] induces the rectification [42]. In brief, the different edge connections can induce a different interface, which exhibits the powerful tunability of the electronic properties.…”

“…The optoelectronic properties of lateral heterostructure devices have been investigated intensively. Some optoelectronic devices exhibit superior optical performance [127][128][129][130]. In lateral graphene-TMDC heterostructures, photons excite electron-hole pairs from the TMDC and rapidly transfer the electrons to the graphene in the Schottky junction, which provides a good photoresponse property.…”

“…The time and temperature are the main factors to control the process. The established TTA framework generalizes the one-step CVD process and complemented the works mainly [21,22,130] on vertical heterostructures and alloys, also concerned with LHS synthesis. This diagram may promote applications of the synthesis technique.…”

“…This diagram may promote applications of the synthesis technique. Graded doped lateral WSe 2 -WS 2 heterostructure has been fabricated using the one-step growth technique in ambient pressure [130]. The one-step CVD method only has one heating cycle, showing merits of simplicity and cheapness.…”