2D platinum diselenides grown on 3D wide-bandgap substrates by Van der Waals epitaxy

PtSe₂ is a 2D material that undergoes phase transition from a semiconductor of Eg≈0.3 eV ∼ 1.4 eV to a type-II Dirac semimetal as its thickness varies. 3D wide band gap semiconductors continue to gain wider acceptance as a substrate material and as an electrode if properly doped. To embrace for broader applications, tractable materials process design rules are essential, especially in understanding the relationships between the Van der Waals epitaxy and the resulted physical properties of the ended products. In this work, ultrathin films of Pt were first deposited by magnetron sputtering on the GaN, AlN and Al2O3 substrates followed by atmospheric pressure chemical vapor deposition (APCVD). Selenization of the Pt films forms uniform and smooth 2D/3D selenide heterostructures. The effects of deposition parameters with respect to the underlying substrates according to the physical properties are investigated. Various spectroscopic means were used to study the samples with well characterized structural properties.