Pulsed thermal deposition of transition metal dichalcogenides
Final Report Abstract
Transition metal dichalcogenides (TMDCs) continue to attract considerable attention as a material platform to study fundamental physical properties of two-dimensional (2D) van der Waals materials and, in view of applications, as extremely thin opto-electronic devices either in the monolayer (ML) limit, or multilayer structure with precisely controlled layer design. In addition to the intriguing properties of the individual layers, the interest in 2D materials is motivated by the fact that they can be combined freely via layer transfer to create new artificial materials. Targeting these exciting fields in the direction of practical applications, however, indispensably requires single crystalline wafer-scale films with tunable material composition, layer thickness, and crystalline perfection comparable to, or even exceeding that of currently available bulk crystals. The synthesis of films satisfying these requirements continues to be very challenging and their exploitation in industrial-scale applications remains unresolved. In this project, a systematic study of transition metal disulfides growth by molecular beam epitaxy using a pulsed thermal deposition technique has been conducted. The growth was performed in a wide range of growth conditions on different single crystalline wafers. A layer-bylayer growth mode, required for the fabrication of continues TMDC monolayers was established on sapphire and Y-stabilized ZrO2. The as grown layers are found to be composed of several-tens nm epitaxial crystallites with in-plane rotational domains due to the difference in the crystal symmetry and large lattice mismatch with the wafer. The fine crystalline structure of the films, appearing as a result of a strong interaction with the substrate, negatively affects optical and electrical properties of the layers. The subsequent annealing of the samples in a sulfur environment leads to the layer recrystallization significantly increasing the size of the domains, accompanied by the disappearance of the defect-related peaks in Raman spectra, sharpening the excitonic signatures in absorption and strong enhancement of the photoluminescence yield for semiconducting materials. While the structural perfection of the materials has to be still improved, the developed procedure already allows to fabricate metal-semiconductor vertical heterostructures exhibiting smooth surface morphology and absence of intermixing according to the optical and X-ray diffraction measurements. The results provide a solid foundation for fabricating of wafer-scale epitaxial transition metal dichalcogenide complex multilayer structures on non-van der Waals substrates.
Publications
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Recrystallization of MBE‐Grown MoS2 Monolayers Induced by Annealing in a Chemical Vapor Deposition Furnace. physica status solidi (RRL) – Rapid Research Letters, 17(5).
Wang, Rongbin; Koch, Norbert; Martin, Jens & Sadofev, Sergey
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Strong coupling of monolayer Strong coupling of monolayer WS2 excitons and surface plasmon polaritons in a planar Ag/WS2 hybrid structure. Physical Review B, 108(16).
Zorn, Morales Nicolas; Rühl, Daniel Steffen; Sadofev, Sergey; Ligorio, Giovanni; List-Kratochvil, Emil; Kewes, Günter & Blumstengel, Sylke
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Y‐Stabilized ZrO2 as a Promising Wafer Material for the Epitaxial Growth of Transition Metal Dichalcogenides. physica status solidi (RRL) – Rapid Research Letters, 18(1).
Wang, Rongbin; Schmidbauer, Martin; Koch, Norbert; Martin, Jens & Sadofev, Sergey
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“Recrystallization of epitaxial MBE- grown MoS2 monolayers induced by annealing in a CVD furnace”, 2D Transition Metal Dichalcogenides, Cambridge, United Kingdom, June 26-29, 2023
S. Sadofev; Rongbin Wang; N. Koch; M. Schmidbauer & J. Martin
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“Recrystallization of epitaxial MBE-grown MoS2 monolayers induced by annealing in a CVD furnace”, chem2Dmat European conference on chemistry of two-dimensional materials Bologna, Italy, May 15-18, 2023
S. Sadofev; Rongbin Wang; N. Koch & J. Martin
