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HL: Fachverband Halbleiterphysik

HL 18: 2D Materials and Heterostructures: Emerging Materials and Phenomena

HL 18.12: Talk

Tuesday, March 19, 2024, 12:30–12:45, EW 201

Impact of atomic layer deposition growth rate on the properties of MoS₂ and WS₂ — •Christian Tessarek, Tim Grieb, Florian F. Krause, Christian Petersen, Alexander Karg, Alexander Hinz, Niels Osterloh, Christian Habben, Stephan Figge, Andreas Rosenauer, and Martin Eickhoff — Institute of Solid State Physics, University of Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany

The direct band gap of monolayer MoS₂ and WS₂ enables the use of these layers in optoelectronic applications. To overcome the limited and random size of exfoliated flakes from bulk material, chemical vapor deposition (CVD) techniques are necessary to grow homogeneous layers on large substrates.

Atomic layer deposition, a modified CVD method using an alternating precursor supply at lower process temperature, was used to grow MoS₂ and WS₂ on SiO₂/Si substrates. The growth rate is identified as a major parameter that influences the optical and structural properties. Raman spectroscopy investigations were carried out to characterize the 2D layers. Monolayers only form applying a slow growth rate. For a fast growth rate multilayers with minor structural properties directly develop in the initial phase. The optical activity was demonstrated by photoluminescence measurements which show typical A and B excitonic emission for MoS₂ and WS₂ monolayers. Further studies by X-ray photoelectron spectroscopy and transmission electron microscopy were carried out to reveal the stoichiometry and crystalline quality of the layers.

Keywords: MoS2; atomic layer deposition; growth rate; Raman spectroscopy; photoluminescence spectroscopy