Scrutinizing pre- and post-device fabrication properties of atomic layer deposition WS2 thin films
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Date
2023-07-06
Authors
Coleman, Emma
Monaghan, Scott
Gity, Farzan
Mirabelli, Gioele
Duffy, Ray
Sheehan, Brendan
Balasubramanyam, Shashank
Bol, Ageeth A.
Hurley, Paul K.
Journal Title
Journal ISSN
Volume Title
Publisher
AIP Publishing
Published Version
Abstract
In this work, we investigate the physical and electrical properties of WS2 thin films grown by a plasma-enhanced atomic layer deposition process, both before and after device fabrication. The WS2 films were deposited on thermally oxidized silicon substrates using the W(NMe2)2(NtBu)2 precursor and a H2S plasma at 450 °C. The WS2 films were approximately 8 nm thick, measured from high-resolution cross-sectional transmission electron imaging, and generally exhibited the desired horizontal basal-plane orientation of the WS2 layers to the SiO2 surface. Hall analysis revealed a p-type behavior with a carrier concentration of 1.31 × 1017 cm−3. Temperature-dependent electrical analysis of circular transfer length method test structures, with Ni/Au contacts, yielded the activation energy (Ea) of both the specific contact resistivity and the WS2 resistivity as 100 and 91 meV, respectively. The similarity of these two values indicates that the characteristics of both are dominated by the temperature dependence of the WS2 hole concentration. Change in the material, such as in sheet resistance, due to device fabrication is attributed to the chemicals and thermal treatments associated with resist spinning and baking, ambient and UV exposure, metal deposition, and metal lift off for contact pad formation.
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Keywords
Hall effect , Electrical properties and parameters , Electric measurements , Materials heat treatment , Atomic force microscopy , Atomic layer deposition , Metal deposition , Thin films , Transmission electron microscopy
Citation
Coleman, E., Monaghan, S., Gity, F., Mirabelli, G., Duffy, R., Sheehan, B., Balasubramanyam, S., Bol, A.A. and Hurley, P. (2023) ‘Scrutinizing pre- and post-device fabrication properties of atomic layer deposition WS2 thin films’, Applied Physics Letters, 123(1), 011901, https://doi.org/10.1063/5.0151592.