Optoelectronics and Nanophotonics of Vapor–Liquid–Solid Grown GaSe van der Waals Nanoribbons

Abstract

2D/layered semiconductors are of interest for fundamental studies and for applications in optoelectronics and photonics. Work to date focused on extended crystals, produced by exfoliation or growth and investigated by diffraction-limited spectroscopy. Processes such as vapor−liquid−solid (VLS) growth carry potential for mass-producing nanostructured van der Waals semiconductors with exceptionally high crystal quality and optoelectronic/photonic properties at least on par with those of extended flakes. Here, we demonstrate the synthesis, structure, morphology, and optoelectronics/photonics of GaSe van der Waals nanoribbons obtained by Au-and Ag-catalyzed VLS growth. Although all GaSe ribbons are high-quality basal-plane oriented single crystals, those grown at lower temperatures stand out with their remarkably uniform morphology and low edge roughness. Photoluminescence spectroscopy shows intense, narrow light emission at the GaSe bandgap energy. Nanophotonic experiments demonstrate traveling waveguide modes at visible/near-infrared energies and illustrate approaches for locally exciting and probing such photonic modes by cathodoluminescence in transmission electron microscopy.

P Doping Promotes the Spontaneous Visible-Light-Driven Photocatalytic Water Splitting in Isomorphic Type II GaSe/InS Heterostructure

“…First, it is necessary to optimize the geometry of GaSe and InS monolayers to understand their structural characteristics and obtain the most stable structure. The lattice parameters of GaSe and InS monolayers after structural optimization are 3.77 and 3.89 Å, respectively, which are similar to the results of previous studies. − The symmetry space groups of them are both P 3 m 1 (no. 156).…”

Br-Induced Orientation Control of PbI2 van der Waals Nanowires and Their Optoelectronics

“…The GeS vdW layers grown with Au catalysts display helical nanowire growth with continuous interlayer twists, suggesting tunable optical/thermal conductivity . Furthermore, VLS-grown Ge 1– x Sn x S or GaSe nanoribbons exhibit excitonic emission with waveguide modes, potentially useful for photonic applications. These examples suggest that there is a unique design space for the vdW-layered material systems when the VLS approach is applied, including variable stacking orientation (i.e., vertical/horizontal) or stacking sequence, in which a high level of control is critical for investigating new functionalities in optoelectronics or nanophotonics .…”

Gallium Selenide Nanoribbons on Silicon Substrates for Photodetection

“…Typical diameters of the In droplets ranged from 11 to 20 nm, with an average size of 15 nm and a density of 1 × 10 9 cm –2 , measured from AFM acquisition. Some previous studies have used gallium, gold, selenium, or silver droplets as catalysts for the growth of III–VI nanowires or NRs ,,,,− (by CVD or in horizontal furnace). Here, we have chosen indium as it is compatible with our 300 mm MOCVD cluster tool.…”

“…The growth of 2D material-based nanowires and nanoribbons (NRs) has already been explored. − Different growth approaches have been studied and it is either possible to grow nano-objects with a relation of epitaxy with the substrate ,, or without, via different growth mechanisms such as vapor–liquid–solid or vapor–solid, for example. Among them, three groups have investigated the potential of GaSe one-dimensional objects for photodetection ,, revealing slow response time (on the order of some hundreds of milliseconds), potentially due to the existence of defects in the nanostructures creating charge traps.…”