TEMPLATE DIRECTED FORMATION OF METALLIC IN/(0001) SURFACE OF Sb2Te3 2D LAYERED SEMICONDUCTOR SELF-ASSEMBLING NANOSYSTEM

Abstract

The cleavage surface of Sb 2 Te 3 layered chalcogenide crystal like as other 2D layered ones, such as InSe, In 4 Se 3 , InTe, is provided as a nanoscale embossed template for the formation of arrays of self-assembled In nanostructures due to thermal deposition and subsequent solid state dewetting (SSD) procedure. Sb 2 Te 3 samples were characterised by X –ray diffraction (XRD), X –ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED) and scanning tunneling microscopy/spectroscopy (STM/STS). Sb 2 Te 3 has got the anisotropic crystal structure with the presence of van der Waals interlayer interactions. The studied (0001) surfaces were stable with a specific surface relief, which, as in the cases of other layered crystals In 4 Se 3 , InSe, InTe, is due to the crystal structure of the layer package. The shape of single In induced nanostructure and their array’s symmetry are directed by the (0001) surface lattice symmetry. We observed the formation of triangular shaped In nanostructures ordered in hexagonal structured arrays with the well-defined lattice parameter after the SSD. That is, it can be argued that the cleavage (0001) surface of the Sb 2 Te 3 crystal actually works as a spatially distributed ordered set of cells, which act as a guiding factor for the self-organization of nanostructures due to SSD process on the macroscale. The comparative fractal analysis of STM images of the (0001) Sb 2 Te 3 and (0001) InSe surfaces, shows that distribution in size of In nanostructures are almost the same under commensurate experimental conditions. Sb 2 Te 3 energy gap determined from STS spectra of initial surfaces is approaching value of 0.2 eV. An increase in the degree of In coverage is expressed in DOS distribution with appearance of its sufficient value in the range of Sb 2 Te 3 energy gap. Keywords: layered crystal chalcogenides, self-assembled nanostructures, nanostructures’ template directed assembly, hetero nanostructures, solid state dewetting, LEED, STM/STS, XPS.