研究目的
To fabricate a graphene/h-BN/SiO2 heterostructure by direct chemical vapor deposition without mechanical transfer processes and investigate its electronic structures and interfacial properties for improved graphene device performance.
研究成果
The h-BN buffer layer promotes direct graphene growth on SiO2 with improved uniformity and reduced interfacial interactions, but oxygen impurities in h-BN require optimization for practical device applications.
研究不足
The h-BN layer contains oxygen substitutional impurities (BN3?xOx), which may affect device performance. The growth temperature (1273 K) is relatively low, leading to small grain size in graphene. Further investigations are needed to fabricate impurity-free h-BN layers.
1：Experimental Design and Method Selection:
The study employed chemical vapor deposition (CVD) for direct growth of h-BN and graphene layers on SiO2 substrates to avoid contamination from transfer processes. NEXAFS and micro-Raman spectroscopy were used to analyze electronic structures and crystallinity.
2：Sample Selection and Data Sources:
A Si(100) wafer with a 300 nm thick oxidized layer (SiO2) was used as the substrate. Samples included pristine SiO2, h-BN/SiO2, and graphene/h-BN/SiO2 heterostructures.
3：List of Experimental Equipment and Materials:
Custom-designed vacuum furnace, methanol vapor, ammonia borane, micro-Raman spectrometer (Tokyo Instruments NANOFINDER), atomic force microscope (SII SPA 300), XPS with Mg Kα source (PSP TX400/2), NEXAFS at BL-8 of SR center.
4：Experimental Procedures and Operational Workflow:
Substrates were cleaned ultrasonically and with UV/ozone, degassed at 1173 K. h-BN was grown by exposing to ammonia borane gas at 1273 K, followed by graphene growth using methanol vapor at 1273 K. Characterization involved Raman spectroscopy, AFM, XPS, and NEXAFS measurements with specific incident angles.
5：Data Analysis Methods:
XPS data analyzed for core level shifts and intensity ratios; Raman spectra analyzed for peak positions and intensities; NEXAFS spectra analyzed for π* and σ* peak intensities and incident angle dependencies.
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