Dilute Rhenium Doping and its Impact on Defects in MoS₂

Abstract

Substitutionally doped 2D transition metal dichalcogenides are primed for next-generation device applications such as field effect transistors (FET), sensors, and optoelectronic circuits. In this work, we demonstrate substitutional rhenium (Re) doping of MoS 2 monolayers with controllable concentrations down to 500 ppm by metal− organic chemical vapor deposition (MOCVD). Surprisingly, we discover that even trace amounts of Re lead to a reduction in sulfur site defect density by 5−10×. Ab initio models indicate the origin of the reduction is an increase in the free-energy of sulfur-vacancy formation at the MoS 2 growth-front when Re is introduced. Defect photoluminescence (PL) commonly seen in undoped MOCVD MoS 2 is suppressed by 6× at 0.05 atomic percent (at. %) Re and completely quenched with 1 at. % Re. Furthermore, we find that Re-MoS 2 transistors exhibit a 2× increase in drain current and carrier mobility compared to undoped MoS 2 , indicating that sulfur vacancy reduction improves carrier transport in the Re-MoS 2 . This work provides important insights on how dopants affect 2D semiconductor growth dynamics, which can lead to improved crystal quality and device performance.

Air-Stable, Large-Area 2D Metals and Semiconductors

“…STEM analysis performed on 5000 Se sites in the STEM images of MoSe 2 and W 0.18 Mo 0.82 Se 2 shows that the percentage of Se vacancies was reduced from (4 ± 0.06)% to (2 ± 0.08)% . This phenomenon was attributed to a stronger bonding strength and higher formation energy of Se vacancy in the presence of W in MoSe 2 . However, it was not rigorously verified.…”

“…Inspired by the hydrogen intercalation at EG/SiC interface, many efforts have been made to intercalate metal atoms into the EG/SiC interface to form confined 2D metals. Most of the confined growths of 2D metals are achieved by intercalation under ultrahigh vacuum (UHV). − First, metal atoms are deposited on the buffer or EG surface via thermal or E-beam evaporation, sputtering, or MBE. Then metal/EG/SiC is annealed under vacuum and metal atoms will enter EG/SiC interface.…”

“…The corresponding energy values as a function of the Re position are listed. (c–g) Adapted with permission from ref . Copyright 2023 American Chemical Society.…”

“…(a) Transfer characteristics for undoped, H 2 S annealed, and 0.1 atom % Re-MoS 2 FETs measured in ambient conditions and their (b) statistical analysis of V TH at V DS = 1 V The red horizontal line in each graph marks I DS at 10 –5 A/mm. (a, b) Adapted and modified with permission from ref . Copyright 2023 American Chemical Society.…”

A Molecular Coordination Strategy for Regulating the Interface of MoS2 Field Effect Transistors

“…In general, the modification of TMDs can be conducted at both the atomic and molecular levels. Atomically modifying TMDs mainly adopts the substitutional element doping strategy, in which foreign atoms are injected into TMDs through chemical vapor deposition, − homogeneous etching, − and other methods . However, substitutional element doping often causes damage to the surface of TMDs and introduces defects in the lattices, resulting in a large number of carriers scattering and capture centers, thereby reducing the interface charge transport efficiency. , Molecular modification methods for TMDs consist of thermal evaporation, ,,, solution spin coating, , and solution drop casting and soaking. ,− Among these methods, the target small molecules or polymers are typically immobilized on the surfaces of TMDs through physisorption.…”