Doping two-dimensional (2D) semiconductors beyond their degenerate levels provides the opportunity to investigate extreme carrier density-driven superconductivity and phase transition in 2D systems. Chemical functionalization and the ionic gating have achieved the high doping density, but their effective ranges have been limited to ∼1 nm, which restricts the use of highly doped 2D semiconductors. Here, we report on electron diffusion from the 2D electride [Ca2N]+·e- to MoTe2 over a distance of 100 nm from the contact interface, generating an electron doping density higher than 1.6 × 1014 cm-2 and a lattice symmetry change of MoTe2 as a consequence of the extreme doping. The long-range lattice symmetry change, suggesting a length scale surpassing the depletion width of conventional metal-semiconductor junctions, was a consequence of the low work function (2.6 eV) with highly mobile anionic electron layers of [Ca2N]+·e-. The combination of 2D electrides and layered materials yields a novel material design in terms of doping and lattice engineering.
Bibliographical noteFunding Information:
This work was supported by Samsung Research Funding & Incubation Center of Samsung Electronics under Project Number SRFC-MA1701-01 (H.Y.), the Creative Materials Discovery Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science ICT, and Future Planning (2015M3D1A1070639) (S.W.K.), the Institute for Basic Science (IBS-R011-D1) (Y.H.L.), and Samsung Science and Technology Foundation under Grant No. SSTF-BA1401-08 (D.H.C. and K.J.C.).
© 2017 American Chemical Society.
- electron diffusion
- phase transition
- work function