Atomically Thin Layers of MoS₂ Grown by the Method of Pulsed Laser Deposition

Abstract

This paper presents the results on the synthesis and study of the properties of monolayer and multilayer films obtained by pulsed laser deposition on glass substrates. Atomic force microscopy (AFM), X-ray diffractometry, Raman scattering spectroscopy, optical absorption, photoluminescence and Hall measurements were used to characterize the structural, morphological, optical and electrical properties of the films. The discovered experimental features of ultra-thin films indicate the evolution of all the properties of such a two-dimensional material with an increase in the number of atomic layers. The material becomes direct-gap semiconductor in the limit of one or two monolayer thicknesses, and optical absorption and photoluminescence at room temperature are due to the generation and recombination of two-dimensional excitons with a binding energy of the order of 0.45 eV. Depending on the deposition regimes, the layers may contain vacancies or an excess of sulfur atoms, leading to the n- or p-type conductivity, respectively.