研究目的
To investigate the direct successive MOVPE of MoS2/WS2 and WS2/MoS2 heterostructures on sapphire substrates and the deposition of large-scale MoS2/graphene and WS2/graphene heterostructures using only MOVPE, analyzing the influence of growth time on nucleation of WS2 on graphene.
研究成果
Large-scale MoS2/WS2 and WS2/MoS2 heterostructures were successfully deposited using MOVPE, with good homogeneity and quality. The first large-scale WS2/graphene and MoS2/graphene heterostructures using only CVD processes were demonstrated. The study highlights the importance of efficient control of nucleation for 2D-on-2D deposition.
研究不足
The coverage of WS2 on graphene is limited by preferential nucleation at graphene grain boundaries and multilayer growth at the same nucleation sites. The growth behavior of WS2 on MoS2 is difficult to compare due to inhomogeneous MoS2 layers.
1：Experimental Design and Method Selection:
The study employs MOVPE for the deposition of 2D-2D heterostructures on sapphire substrates, focusing on MoS2/WS2, WS2/MoS2, WS2/graphene, and MoS2/graphene combinations. The methodology includes the use of molybdenum hexacarbonyl and tungsten hexacarbonyl as metal sources and di-tert-butyl sulfide as the sulfur source.
2：Sample Selection and Data Sources:
Sapphire (0001) substrates with a nominal offcut of 0.2° towards m-plane are used. Graphene films are deposited on sapphire substrates in an AIXTRON CCS 2D system.
3：2° towards m-plane are used. Graphene films are deposited on sapphire substrates in an AIXTRON CCS 2D system.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: AIXTRON planetary hot-wall reactor, AIXTRON CCS 2D system, Renishaw inVia Raman spectrometer, SEM for morphology analysis.
4：Experimental Procedures and Operational Workflow:
The deposition processes involve a one-step growth process in N2 atmosphere, with specific temperatures and pressures for each material combination. The growth time is varied to study its effect on nucleation and coverage.
5：Data Analysis Methods:
Raman spectroscopy, photoluminescence spectroscopy, and SEM are used to analyze the morphology and properties of the heterostructures.
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