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DOI: 10.1002/aelm.202000616 devices, which can accommodate various materials via stacking. With respect to future applications, WSe2 exhibits strong potential to be used in field-effect transistors (FETs), photodetectors, light-emitting diodes, and solar cells.[5–9] The metal–semiconductor (MS) interface is a critical factor influencing the electronic performance of 2D WSe2 devices in that it is strongly correlated to device polarity.[10] Thus, the Schottky barrier height (SBH) is also an important parameter of the MS interface. In principle, the SBH can be determined according to the Schottky–Mott rule as the difference between the metal work function and the conduction-band edge or valenceband edge for n-type or p-type transistors, respectively.[11,12] However, the SBH in an actual device deviates from the Schottky– Mott rule because of the interfacial energy states.[13] This phenomenon is known as Fermi-level pinning (FLP), and the extent of FLP is quantified by the pinning factor. The pinning factor takes a value from S = 1 for no pinning to S = 0 for complete pinning. Thus, a novel method is needed to alleviate the FLP of 2D WSe2 devices and to control their carrier transport properties. Recently, various methods have been proposed to control the FLP of 2D materials, including transferring preformed metals instead of depositing them by evaporation[14,15] and using the edge contact.[16] Nevertheless, most of the proposed techniques involve complicated processes with poorly reproducible results. Here, a polymer-based dopant is introduced for contact engineering because of its convenience, low processing cost, and reliability. In this work, we attempted to elucidate the effect of a polymeric n-type dopant on the contact properties of WSe2 devices, focusing on modulating the potential barrier of the MS interface, and thereby the transport mechanism, to promote tunneling current at the MS interface. This idea was proposed for TMDCs in previous research;[17,18] however, no experimental results have been reported to support it for WSe2. To achieve this objective, we used spin-coated polyvinyl alcohol (PVA) as the dopant for WSe2 FETs with lowand high-work-function metals (In and Pd, respectively) to demonstrate a clear difference in the transformation of the potential barrier structure. We demonstrate the transition of the potential barriers at the MS interface by measuring the SBH before and after doping. To clarify the results of our SBH measurements, we characterized Tungsten diselenide (WSe2) is attracting attention because of its superior electronic and optoelectronic properties. In recent years, the number of research works related to the WSe2-based field-effect transistors (FETs) has increased dramatically. Nonetheless, the performance of 2D WSe2 is influenced sensitively by metal–semiconductor (MS) interface states, where Fermilevel pinning is substantial. This research explores Fermi-level depinning by doping with an n-type polymer. In this work, spin-coated polyvinyl alcohol (PVA) is used as an n-type dopant for achieving low-contact-resistance WSe2 FETs in cases of both high-work-function (Pd) and low-work-function (In) metals. Interestingly, the increase in the Schottky barrier height resulting from the application of PVA gives rise to Fowler–Nordheim tunneling for a doped Pd-WSe2 contact. By contrast, only direct tunneling is observed for an In-WSe2 contact irrespective of whether the dopant is used. The barrierheight modification after doping reveals that the improvement of the contact resistance is correlated to the enhancement of tunneling current after doping, which is consistent with the measurement results. This work suggests a practical direction for contact engineering of future WSe2-based electronic devices and expands the current understanding of charge transport at the MS contact when a polymeric n-type dopant is applied.