Layer-by-Layer Thinning of PdSe 2 Flakes via Plasma Induced Oxidation and Sublimation.

Authors :: Hoffman AN
Gu Y
Tokash J
Woodward J
Xiao K
Rack PD
Source :: ACS applied materials & interfaces [ACS Appl Mater Interfaces] 2020 Feb 12; Vol. 12 (6), pp. 7345-7350. Date of Electronic Publication: 2020 Jan 29.
Publication Year :: 2020
Abstract: Controlled O <subscript>2</subscript> /Ar plasma exposure and subsequent low temperature inert atmosphere annealing of chemical vapor deposition (CVD) grown PdSe <subscript>2</subscript> flakes etch PdSe <subscript>2</subscript> layer-by-layer in an atomic layer etching-like (ALE) process. X-ray photoelectron spectroscopy (XPS) shows that exposure to a remote inductively coupled plasma (ICP) oxygen plasma oxidizes the top layer of the PdSe <subscript>2</subscript> to form PdO <subscript>2</subscript> and SeO <subscript>2</subscript> . After an in situ annealing, XPS shows no trace of PdO <subscript>2</subscript> or SeO <subscript>2</subscript> , suggesting the byproducts are volatile at low temperature. Atomic force microscopy of PdSe <subscript>2</subscript> exposed to various O <subscript>2</subscript> + Ar plasmas (O <subscript>2</subscript> = 25-100%) demonstrates a clear trend between the oxygen concentration and the number of layers etched per cycle. PdSe <subscript>2</subscript> field effect transistors (FETs) were characterized at various stages of two ALE-like cycles, and the electrical properties are correlated to the oxidation and byproduct desorption and layer reduction.

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