Van der Waals epitaxy of ultrathin α-MoO3 sheets on mica substrate with single-unit-cell thickness

• Published in: Applied physics letters Vol. 108; no. 5
• Main Authors: Wang, Di, Li, Jing-Ning, Zhou, Yu, Xu, Di-Hu, Xiong, Xiang, Peng, Ru-Wen, Wang, Mu
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 01-02-2016
• Subjects: Applied physics; Crystal lattices; Crystal structure; Crystallinity; Epitaxial growth; Frequency shift; Graphene; Incident light; Lattice vibration; Molybdenum disulfide; Molybdenum oxides; Molybdenum trioxide; Raman spectra; Sheets; Single crystals; Substrates; Unit cell
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4941402

We report on van der Waals epitaxy of single-crystalline α-MoO3 sheets with single-unit-cell thickness on the mica substrate. The crystalline lattice structure, growth habits, and Raman spectra of the grown α-MoO3 sheets are analyzed. The anisotropic growth of α-MoO3 sheets can be understood by period bond chains theory. Unlike monolayer MoS2 or graphene, Raman spectra of α-MoO3 do not possess frequency shift from bulk crystal to single-unit-cell layer. The relative intensities of two Raman modes (Ag) at 159 and 818 cm−1 are sensitive to the polarization of incident light. This scenario provides a quick approach to determine the lattice orientation of α-MoO3 crystals. Our studies indicate that van der Waals epitaxial growth is a simple and effective way to fabricate high-quality ultrathin α-MoO3 sheets for physical property investigations and potential applications.