Controlled nucleation of monolayer MoSe2 islands on Si (111) by MBE

Abstract

Van der Waals bonding relaxes the constraints of lattice matching, making two-dimensional (2D) transition metal dichalcogenides attractive in the field of epitaxy. Recently, molecular beam epitaxy (MBE) of MoSe2 was demonstrated on a variety of substrates. Here, the authors use MBE to investigate the early stages of 2D nucleation of MoSe2 grown on Si in pursuit of controlled monolayer island size. The 2D nucleation rate varies by a factor of >2 over a narrow substrate temperature range of 550–560 °C. Above 560 °C, the desorption rate of Se from the surface exceeds the nucleation rate leading to fully suppressed 2D monolayer nucleation. X-ray diffraction confirms (001) oriented MoSe2 on Si (111). Raman spectra are consistent with 1–3 monolayer-thick MoSe2, in agreement with atomic force microscopy measurements of the monolayer height of 2D islands.

Nanoscale MoSe2 Grown on Si(111) for Potential Applications in Broadband Photodetectors

“…Remarkably, despite the significant lattice mismatch, we successfully obtain highly oriented and uniform films through van der Waals epitaxy. 3,30 The 2H phase of the MoSe 2 film is confirmed by Raman spectroscopy. Atomic force microscopy (AFM) was employed to study the surface topography of the as-grown films.…”

“…22−28 However, only a few studies on MBE growth of MoSe 2 on Si(111) substrates are available in the literature. 1,3,18,29 The problem with the direct growth on Si(111), as pointed out by Ohtake and Sakuma, is the formation of the MoSi 2 phase, which prohibits further growth of MoSe 2 . 29 Xenogiannopoulou et al reported the growth of MoSe 2 on AlN(0001)/Si(111) and have shown that using the AlN template, it is possible to grow high-quality MoSe 2 films as compared to that on a bare Si substrate.…”

“…1 Intralayer bonding of TMDCs is covalent, while successive interlayer bonding is a weak van der Waals bond. 2,3 In their bulk form, TMDCs exhibit an indirect bandgap, but their monolayers possess a direct bandgap. 4,5 Among the various phases observed in TMDCs, the hexagonal 2H phase shows semiconductor behavior, while the trigonal 1T phase exhibits semimetallic properties.…”

“…These layered materials, known as MX 2 , consist of a transition metal (M), such as Mo, W, or Pt, sandwiched between two planes of chalcogen atoms (X), such as S, Se, or Te . Intralayer bonding of TMDCs is covalent, while successive interlayer bonding is a weak van der Waals bond. , In their bulk form, TMDCs exhibit an indirect bandgap, but their monolayers possess a direct bandgap. , Among the various phases observed in TMDCs, the hexagonal 2H phase shows semiconductor behavior, while the trigonal 1T phase exhibits semimetallic properties. The semiconducting nature of 2D-TMDCs makes them promising candidates for electronic and optoelectronic devices. , There are only two phases (2H and 1T) of MoSe 2 that have been found experimentally, where the 2H phase is thermodynamically stable, whereas the 1T phase is metastable for MoSe 2 , a prominent member of the TMDC family .…”

Self-Assembly of Ge and GaAs Quantum Dots under Tensile Strain on InAlAs(111)A

“…The structural and electronic characteristics of (111) surfaces give rise to properties that are inaccessible to semiconductors with the traditional (001) orientation. (111)-Oriented semiconductor heterostructures are attractive for applications including topological insulators, − transition metal dichalcogenides and other 2D materials, − optoelectronics based on strain-induced piezoelectric effects, , and next-generation field-effect transistors. , …”