Deterministic synthesis of Cu9S5 flakes assisted by single-layer graphene arrays

A Portone and L Bellucci and D Convertino and F Mezzadri and G Piccinini and MA Giambra and V Miseikis and F Rossi and C Coletti and F Fabbri, NANOSCALE ADVANCES, 3, 1352-1361 (2021).

DOI: 10.1039/d0na00997k

The employment of two-dimensional materials, as growth substrates or buffer layers, enables the epitaxial growth of layered materials with different crystalline symmetries with a preferential crystalline orientation and the synthesis of heterostructures with a large lattice constant mismatch. In this work, we employ single crystalline graphene to modify the sulfurization dynamics of copper foil for the deterministic synthesis of large-area Cu9S5 crystals. Molecular dynamics simulations using the Reax force-field are used to mimic the sulfurization process of a series of different atomistic systems specifically built to understand the role of graphene during the sulphur atom attack over the Cu(111) surface. Cu9S5 flakes show a flat morphology with an average lateral size of hundreds of micrometers. Cu9S5 presents a direct band-gap of 2.5 eV evaluated with light absorption and light emission spectroscopies. Electrical characterization shows that the Cu9S5 crystals present high p-type doping with a hole mobility of 2 cm(2) V-1 s(-1).

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