"Horizontal to Vertical Transition of MoS2 grown by CVD on Mo studied by Spectroscopic Ellipsometry"

KAREN NAVARRO; CARLOS MONZÓN; MARTIN PATRITO; JUAN DE PAOLI

Dresden

Congreso; Graphene 2018; 2018

Phantoms Foundation

The control in the orientation of MoS2 layers with respect to the growing substrate is of upmost importance in MoS2 applications. Horizontally aligned MoS2 layers are preferred for microelectronic devices, whereas vertically aligned MoS2 layers are much useful for the hydrogen evolution reaction and energy storage. Fast sulfurization of metal-seeded substrates has been used to grow vertically standing MoS2 nanosheets (1). When Mo thin films (5-25 nm) are deposited on a given substrate, the MoS2growth occurs until the metal film is consumed. However, the growth of MoS2 films on thicker Mo foils has not been investigated yet.In this work we used spectroscopic ellipsometry to investigate the CVD growth of MoS2 as a function of temperature on specular polished molybdenum surfaces exposed to sulphur gas. At around 800 oC the thickness of the MoS2 films obtained from the ellipsometric spectra have an abrupt increase in agreement with the topography observed in SEM images which shows a change from smooth films to structures with vertically aligned layers.