Physico-Chemical nanomaterials science

Solid state dewetting application for In/ (0001) Sb2Te3 2D layered semiconductor nanosystem formation
P.V. Galiy1, T.M. Nenchuk1, A. Ciszewski2, P. Mazur2, V.I. Dzyuba1, T.R. Makar1, O.V. Tsvetkova1
1 Electronics and Computer Technology Department, Ivan Franko Lviv National University, 50 Dragomanov Street, Lviv, 79005, Ukraine.
E-mail: galiy@electronics.lnu.edu.ua
2 Institute of Experimental Physics, University of Wrocław, pl. Maxa Borna 9, 50-204 Wrocław, Poland.

2D layered crystals are one among most perspective templates for self-assembling of metal nanostructures due to the solid state dewetting (SSD) process. Self-assembled indium nanostuctures formation due to SSD on the (0001) UHV cleaved surface of Sb2Te3 crystals applied as template has been studied by scanning tunneling microscopy/spectroscopy (STM/STS). XRD study (STOE STADI P, CuKα1) shows rhombohedral crystal structure (R3m space group, lattice parameters a=4.2654(8), c=30.435(2) Å). The templates have got excellent surface structural quality in macroscale according to low energy electron diffraction and subsequent phase-elemental composition of Sb2Te3 as determined by X-ray photoelectron spectroscopy. 
The STM/STS data were obtained at room temperature with an Omicron NanoTechnology STM/AFM System in UHV better than 10-10 Torr. Thermal evaporator EFM-3 was applied for indium deposition in situ. The deposition rate was kept at approximately 0.01 ML/min.
The study of indium on Sb2Te3 (0001) substrate sub- and monolayer nanosystem formation was conducted as in "visual" STM mode as in current imaging tunneling spectroscopy (CITS) STS mode. We analyzed the array of studied surface areas with 50x50 nm2 dimensions to obtain reliable conclusions about metal - semiconductor hetero nanosystem formation (In/ Sb2Te3 (0001)). Both, STM and spatially distributed STS data give evidence that indium deposited nanostuctures' growth has island like, localized nature with next thermal-activated surface migration. These formed nano structures have got a characteristic triangular shape that agrees well with the corresponding surface pattern inherent in the Sb2Te3 crystal structure, since, it acts as a template. Spatially averaged over the analyzed area STS data show on formation of metallic phase on Sb2Te3 (0001) surface at high indium deposition times and subsequent annealing.