title: Degenerate n-doping of few-layer transition metal dichalcogenides by potassium.
abstract: We report here the first degenerate n-doping of few-layer MoS2 and WSe2 semiconductors by surface charge transfer using potassium. High-electron sheet densities of ~1.0 × 10(13) cm(-2) and 2.5 × 10(12) cm(-2) for MoS2 and WSe2 are obtained, respectively. In addition, top-gated WSe2 and MoS2 n-FETs with selective K doping at the metal source/drain contacts are fabricated and shown to exhibit low contact resistances. Uniquely, WSe2 n-FETs are reported for the first time, exhibiting an electron mobility of ~110 cm(2)/V·s, which is comparable to the hole mobility of previously reported p-FETs using the same material. Ab initio simulations were performed to understand K doping of MoS2 and WSe2 in comparison with graphene. The results here demonstrate the need of degenerate doping of few-layer chalcogenides to improve the contact resistances and further realize high performance and complementary channel electronics.
authors.affiliation: Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, USA.
authors.forename: Hui
authors.initials: H
authors.lastname: Fang
authors.forename: Mahmut
authors.initials: M
authors.lastname: Tosun
authors.forename: Gyungseon
authors.initials: G
authors.lastname: Seol
authors.forename: Ting Chia
authors.initials: TC
authors.lastname: Chang
authors.forename: Kuniharu
authors.initials: K
authors.lastname: Takei
authors.forename: Jing
authors.initials: J
authors.lastname: Guo
authors.forename: Ali
authors.initials: A
authors.lastname: Javey
mesh_terms: D018011:Chalcogens / Q000737:chemistry*; D011188:Potassium / Q000737:chemistry*; D011789:Quantum Theory; D028561:Transition Elements / Q000737:chemistry*
chemical_list: D018011:Chalcogens; D028561:Transition Elements; D011188:Potassium