Engineering The Palladium-WSe₂ Interface Chemistry for Field Effect Transistors with High-Performance Hole Contacts

dc.contributor.ORCID0000-0001-5566-4806 (Wallace, RM)
dc.contributor.ORCID0000-0003-0690-7423 (Young, CD)
dc.contributor.ORCID0000-0003-2781-5149 (Kim, J)
dc.contributor.ORCID0000-0002-6688-8626 (Walsh, LA)
dc.contributor.ORCID0000-0002-5485-6600 (Hinkle, CD)
dc.contributor.ORCID0000-0002-5454-0315 (Addou, R)
dc.contributor.VIAF70133685 (Kim, J)
dc.contributor.authorSmyth, Christopher M.
dc.contributor.authorWalsh, Lee A.
dc.contributor.authorBolshakov, Pavel
dc.contributor.authorCatalano, Massimo
dc.contributor.authorAddou, Rafik
dc.contributor.authorWang, Luhua
dc.contributor.authorKim, Jiyoung
dc.contributor.authorKim, Moon J.
dc.contributor.authorYoung, Chadwin D.
dc.contributor.authorHinkle, Christopher L.
dc.contributor.authorWallace, Robert M.
dc.contributor.utdAuthorSmyth, Christopher M.
dc.contributor.utdAuthorWalsh, Lee A.
dc.contributor.utdAuthorBolshakov, Pavel
dc.contributor.utdAuthorCatalano, Massimo
dc.contributor.utdAuthorAddou, Rafik
dc.contributor.utdAuthorWang, Luhua
dc.contributor.utdAuthorKim, Jiyoung
dc.contributor.utdAuthorKim, Moon J.
dc.contributor.utdAuthorYoung, Chadwin D.
dc.contributor.utdAuthorHinkle, Christopher L.
dc.contributor.utdAuthorWallace, Robert M.
dc.descriptionDue to copyright restrictions and/or publisher's policy full text access from Treasures at UT Dallas is limited to current UTD affiliates (use the provided Link to Article).
dc.description.abstractPalladium has been widely employed as a hole contact to WSe₂ and has enabled, at times, the highest WSe₂ transistor performance. However, there are orders of magnitude variation across the literature in Pd-WSe₂ contact resistance and I-ON/I-OFF ratios with no true understanding of how to consistently achieve high-performance contacts. In this work, WSe₂ transistors with impressive I-ON/I-OFF ratios of 10(6) and Pd-WSe₂ Schottky diodes with near-zero variability are demonstrated utilizing Ohmic-like Pd contacts through deliberate control of the interface chemistry. The increased concentration of a PdSeₓ intermetallic is correlated with an Ohmic band alignment and concomitant defect passivation, which further reduces the contact resistance, variability, and barrier height inhomogeneity. The lowest contact resistance occurs when a 60 min post-metallization anneal at 400 degrees C in forming gas (FG) is performed. X-ray photoelectron spectroscopy indicates this FG anneal produces 3x the concentration of PdSeₓ and an Ohmic band alignment, in contrast to that detected after annealing in ultrahigh vacuum, during which a 0.2 eV hole Schottky barrier forms. Raman spectroscopy and scanning transmission electron microscopy highlight the necessity of the fabrication step to achieve high-performance contacts as no PdSeₓ forms, and WSe₂ is unperturbed by room temperature Pd deposition. However, at least one WSe₂ layer is consumed by the necessary interface reactions that form PdSeₓ requiring strategic exploitation of a sacrificial WSe₂ layer during device fabrication. The interface chemistry and structural properties are correlated with Pd-WSe₂ diode and transistor performance, and the recommended processing steps are provided to enable reliable high-performance contact formation.
dc.description.departmentErik Jonsson School of Engineering and Computer Science
dc.description.sponsorshipNSF Award 1407765; NIST through Award 70NANB17H041; European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant Agreement 713567 and a research grant from Science Foundation Ireland (SFI) under Grant SFI/12/RC/2278
dc.identifier.bibliographicCitationSmyth, Christopher M., Lee A. Walsh, Pavel Bolshakov, Massimo Catalano, et al. 2019. "Engineering the Palladium-WSe₂ Interface Chemistry for Field Effect Transistors with High-Performance Hole Contacts." ACSA Applied Nano Materials 2(1): 75-88, doi: 10.1021/acsanm.8b01708
dc.publisherAmer Chemical Soc
dc.rights©2018 American Chemical Society
dc.source.journalACS Applied Nano Materials
dc.subjectTungsten(IV) Selenide
dc.subjectSurface chemistry
dc.subjectX-ray photoelectron spectroscopy
dc.subjectMolybdenum(IV) Sulfide
dc.subjectMaterials science
dc.titleEngineering The Palladium-WSe₂ Interface Chemistry for Field Effect Transistors with High-Performance Hole Contacts


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