Montagem de um sistema de micro-PL em baixas temperaturas para o estudo de semicondutores bidimensionais

Abstract

Transition metal dicalcogenides (TMDs) are materials that have been attracted great attention in recent years, both from the point of view of fundamental physics and for a new generation of optoelectronic and spintronic devices. In particular, such materials have unique physical properties due to the strong spin-orbit coupling and the valley degree of freedom. Group VI TMD monolayers (2D TMD) are direct band gap semiconductor materials in the K+ and K- valleys of the first Brillouin zone. Due to the breaking of inversion symmetry and the strong spin-orbit coupling, the conduction and valence bands present spin up and down splitting and optical transition selection rules that involve circularly polarized light in the K+ or K- valleys. In this work, it was performed a study of the optical properties of heterostructures based on TMDs monolayers. Recently, it has been demonstrated that the optical and electrical properties of these systems can be improved with the use of insulating materials between SiO2 substrates and TMD monolayers. We propose the use of talc (Mg3Si4O10(OH)2) to isolate two-dimensional TMDs materials from silicon oxide substrates. The work carried out involved: (i) optical assembly of a new micro-PL (micro-photoluminescence) system at UFSCar (ii) the preparation of several samples of MoS2/talc and WS2/talc monolayers and (iii) the characterization of these samples by Raman spectroscopy and micro-PL. In general, the results obtained show that talc is a promising material for applications in optoelectronic devices.