Growth Order-Dependent Strain Variations of Lateral Transition Metal Dichalcogenide Heterostructures

Abstract

Understanding the heterojunction of a lateral heterostructured transition metal dichalcogenide (hTMD) is important in order to take advantage of the combined optoelectronic properties of individual TMDs for various applications but, however, is hampered by mingled effects from lattice mismatch and substrate interaction. Here, we systematically investigated the strain occurring at lateral hTMDs consisting of molybdenum disulfide (MoS2) and molybdenum diselenide (MoSe2) prepared by chemical vapor deposition. Comparison of homologous TMDs and hTMDs from controlled growth order revealed systematic change in photoluminescence behavior depending on substrate interaction and relative lattice mismatch. Near the heterojunction, a TMD with a larger lattice constant (a) exhibits photoluminescence (PL) red-shift, whereas a TMD with smaller a shows an opposite trend owing to lattice-induced strain. These effects are augmented in a subtractive or additive manner by tensile strain from the substrate interaction. Moreover, comparison of PLs revealed that the shell region grown from the core edges exhibits weak substrate interaction contrasted by that of a shell region independently grown on a shell. This study provides detailed understandings of the heterojunction at a lateral hTMD for various applications.

Long-Term Exposure of MoS2 to Oxygen and Water Promoted Armchair-to-Zigzag-Directional Line Unzippings

“…CVD-grown triangular MoS 2 crystals were single crystals terminated with zz edges [ 37 ] and were used to probe the effects of oxidation reactions on the morphological and optoelectronic properties. The MoS 2 crystals were grown by CVD, using the procedure developed in our previous investigation [ 27 ], starting with MoO 3 and sublimed sulfur (see Materials and Methods section). First, a well-dispersed aqueous MoO 3 dispersion containing 1 wt.…”

“…Sulfur was further recrystallized using vacuum sublimation at ca. 10 −3 torr, as described previously [ 27 ]. Sodium cholate (SC), with a purity of over 98%, was purchased from TCI (Tokyo, Japan) and used as a surfactant and an adhesion promoter to a silicon substrate.…”

“…MoS 2 was prepared by using a hot-wall CVD apparatus [ 29 ] operating at atmospheric pressure, with the aforementioned spin-coated MoO 3 and the sublimed sulfur powder as precursors, modified from the previous study [ 27 ]. Prior to the MoS 2 growth, a quartz tube in a tube furnace was pre-annealed for 30 min at 1000 °C with a 20 standard cubic centimeter per min (sccm) Ar flow to remove any physisorbed water, in a CVD chamber.…”

“…The samples were loaded into an environmental chamber (TS1000V-17/3 with T96-S, Linkam Scientific Instruments Ltd., Redhill, UK) which allowed observation of the sample through a coverslip while measurements were made. Raman and PL spectra were obtained using a micro-Raman spectroscopy setup with a backscattering geometry, as described in the literature [ 27 , 29 , 31 ]. Briefly, a spectrometer (Triax 320 with 1800 gr/mm) and coverslip-tolerant 40× objective (UPlanSApo, N.A.…”

Strain‐Dependent Band Structures and Electronic Properties in Sb/Bi Lateral Heterostructures Calculated by First Principles

“…[24][25][26] Transitionmetal dichalcogenide LHSs, such as hexagonal boron nitrides and other materials, have been implemented. [27][28][29][30][31][32][33] Recently, group V materials were used in 2D structures because they feature various adjustable bandgaps that can meet semiconductor device requirements. Specifically, antimony (Sb) and bismuth (Bi) have been examined recently in theoretical calculations and experimental studies.…”