10.1021/nn5047844.s001
Peida Zhao
Peida
Zhao
Daisuke Kiriya
Daisuke
Kiriya
Angelica Azcatl
Angelica
Azcatl
Chenxi Zhang
Chenxi
Zhang
Mahmut Tosun
Mahmut
Tosun
Yi-Sheng Liu
Yi-Sheng
Liu
Mark Hettick
Mark
Hettick
Jeong Seuk Kang
Jeong Seuk
Kang
Stephen McDonnell
Stephen
McDonnell
Santosh KC
Santosh
KC
Jinghua Guo
Jinghua
Guo
Kyeongjae Cho
Kyeongjae
Cho
Robert M. Wallace
Robert M.
Wallace
Ali Javey
Ali
Javey
Air Stable p‑Doping of WSe<sub>2</sub> by Covalent Functionalization
American Chemical Society
2014
transition metal dichalcogenides
XAS
XPS
hole concentration
WSe 2
Se vacancy sites
TMDC
spectroscopy
Covalent FunctionalizationCovalent functionalization
Ab initio simulations
WSe 2 thickness
2014-10-28 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Air_Stable_p_Doping_of_WSe_sub_2_sub_by_Covalent_Functionalization/2241469
Covalent functionalization of transition metal dichalcogenides (TMDCs) is investigated for air-stable chemical doping. Specifically, p-doping of WSe<sub>2</sub> <i>via</i> NO<sub><i>x</i></sub> chemisorption at 150 °C is explored, with the hole concentration tuned by reaction time. Synchrotron based soft X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) depict the formation of various WSe<sub>2–<i>x</i>–<i>y</i></sub>O<sub><i>x</i></sub>N<sub><i>y</i></sub> species both on the surface and interface between layers upon chemisorption reaction. <i>Ab initio</i> simulations corroborate our spectroscopy results in identifying the energetically favorable complexes, and predicting WSe<sub>2</sub>:NO at the Se vacancy sites as the predominant dopant species. A maximum hole concentration of ∼10<sup>19</sup> cm<sup>–3</sup> is obtained from XPS and electrical measurements, which is found to be independent of WSe<sub>2</sub> thickness. This degenerate doping level facilitates 5 orders of magnitude reduction in contact resistance between Pd, a common p-type contact metal, and WSe<sub>2</sub>. More generally, the work presents a platform for manipulating the electrical properties and band structure of TMDCs using covalent functionalization.