Free-standing large, ultrathin germanium selenide van der Waals ribbons by combined vapor–liquid–solid growth and edge attachment

Abstract

High-yield synthesis of large, ultrathin GeSe ribbons combining longitudinal vapor–liquid–solid growth with lateral edge incorporation. Intense luminescence confirms high quality GeSe with low concentration of nonradiative recombination centers.

The Interfacial Properties of Monolayer MX–Metal Contacts

“…Samely the bandgap of MXs decreases in the order of MS>MSe>MTe, since the atomic number of X increases in the order of S < Se < Te, resulting in the strength of interaction between M & X decreases in the order of MS > MSe > MTe. 12,48,49 That is to say the stronger interaction of M and X, the bigger bandgap of MXs. For the same reason, the structure anisotropy factor κ of ML MXs decrease in the same order GeS (0.098) > SnS (0.048) > GeSe(0.034) > SnSe(0.03) > GeTe (0.016) > SnTe (0.009).…”

“…11 Therefore, it is quite promising for ML MXs to be used in electronics and optoelectronics applications. 12 According to ab initio quantum transport simulations, ML GeSe, GeS metal-oxide-semiconductor field-effect transistors (MOSFETs) and ML GeSe, SnSe tunneling fieldeffect transistors (TFETs) [13][14][15] can satisfy the high-performance (HP) applications of the International Technology Roadmap for Semiconductors (ITRS).…”

Phase-Specific Vapor–Liquid–Solid Growth of GeSe and GeSe2 van der Waals Nanoribbons and Formation of GeSe–GeSe2 Heterostructures

“…The presence of Au particles at the tips of the GeSe 2 ribbons suggests that the growth from GeSe and Se vapors proceeds via a VLS mechanism. Similar to the VLS growth of other van der Waals nanostructures, such as GeS nanowires, GeSe, and GaSe nanoribbons, the combination of GeSe and Se precursors used here appears to combine with Au nanoparticles to form a (quasi)-binary eutectic, which acts as the active VLS catalyst in the growth of GeSe 2 ribbons. In a pure VLS growth, the ribbons should maintain constant lateral dimensions defined by the size of the catalyst drop.…”

“…Phase-controlled vapor–liquid–solid (VLS) growth of germanium selenide nanoribbons was carried out in a two-zone tube furnace by vapor transport of the precursors on Si(100) substrates covered by thin (2–5 nm) Au films, which dewetted into polydisperse Au particle VLS catalysts at the growth temperature (see Methods for details). Growth from a pure GeSe precursor (evaporated as an intact formula unit) at substrate temperatures between 280 and 340 °C resulted in forests of GeSe nanoribbons, with individual ribbons shown in Figure a. Switching the product to GeSe 2 ribbons requires two changes to the growth process: (i) addition of selenium to the vapor-phase precursor by thermal evaporation from a separate crucible with molten Se and (ii) an increase in the substrate temperature to 400−450 °C.…”

“…The existence of multiple stable layered phases with different stoichiometry distinguishes these materials from most other two-dimensional (2D)/layered semiconductors. The group IV monochalcogenides generally crystallize with anisotropic orthorhombic layered structures (GeSe, , GeS, , SnS, , etc. ) analogous to black phosphorous, while the dichalcogenides exhibit various 2D layered (trigonal for SnS 2 and SnSe 2 ; monoclinic for GeSe 2 , etc.)…”