The residue of common photo‐ and electron‐beam resists, such as poly(methyl methacrylate) (PMMA), is often present on the surface of 2D crystals after device fabrication. The residue degrades device properties by decreasing carrier mobility and creating unwanted doping. Here, MoS2and WSe2field effect transistors (FETs) with residue are cleaned by contact mode atomic force microscopy (AFM) and the impact of the residue on: 1) the intrinsic electrical properties, and 2) the effectiveness of electric double layer (EDL) gating are measured. After cleaning, AFM measurements confirm that the surface roughness decreases to its intrinsic state (i.e., ≈0.23 nm for exfoliated MoS2and WSe2) and Raman spectroscopy shows that the characteristic peak intensities (E2gand A1g) increase. PMMA residue causes p‐type doping corresponding to a charge density of ≈7 × 1011cm−2on back‐gated MoS2and WSe2FETs. For FETs gated with polyethylene oxide (PEO)76:CsClO4, removing the residue increases the charge density by 4.5 × 1012cm−2, and the maximum drain current by 247% (statistically significant,
From its inception, extensive work on the characterization of field effect transistors (FETs) based on 2D‐layered semiconductors has relied on a back‐gated transistor architecture. This is useful for initial assessment but lacks ultimate compatibility with integrated circuit (IC) design since the threshold voltage of individual devices cannot be controlled independently in order to achieve specific ON‐state and OFF‐state performance. Note that threshold engineering via gate electrostatics is inevitable for 2D semiconductors owing to the absence of comprehensive, reliable, and universal doping schemes. In recent years, several strategies are adopted for the gating of individual 2D‐FETs such as atomic layer deposition (ALD) of high‐
- NSF-PAR ID:
- 10461688
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Electronic Materials
- Volume:
- 5
- Issue:
- 4
- ISSN:
- 2199-160X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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