Control of polarity in multilayer MoTe2 field-effect transistors by channel thickness

Asha Rani; Kyle DiCamillo; Sergiy Krylyuk; Ratan Debnath; Payam Taheri; Makarand Paranjape; Can E Korman; Mona E Zaghloul; Albert V Davydov

doi:10.1117/12.2503888

Control of polarity in multilayer MoTe₂ field-effect transistors by channel thickness

Proc SPIE Int Soc Opt Eng. 2018:10725:10.1117/12.2503888. doi: 10.1117/12.2503888.

Authors

Asha Rani¹, Kyle DiCamillo², Sergiy Krylyuk^{3

4}, Ratan Debnath⁴, Payam Taheri⁴, Makarand Paranjape², Can E Korman¹, Mona E Zaghloul¹, Albert V Davydov⁴

Affiliations

¹ School of Engineering and Applied Science, The George Washington University, Washington, DC 20052, USA.
² Department of Physics, Georgetown University, Washington, DC 20057, USA.
³ Theiss Research, La Jolla, CA 92037, USA.
⁴ Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.

Abstract

In this study, electronic properties of field-effect transistors (FETs) fabricated from exfoliated MoTe₂ single crystals are investigated as a function of channel thickness. The conductivity type in FETs gradually changes from n-type for thick MoTe₂ layers (above ≈ 65 nm) to ambipolar behavior for intermediate MoTe₂ thickness (between ≈ 60 and 15 nm) to p- type for thin layers (below ≈ 10 nm). The n-type behavior in quasi-bulk MoTe₂ is attributed to doping with chlorine atoms from the TeCl₄ transport agent used for the chemical vapor transport (CVT) growth of MoTe₂. The change in polarity sign with decreasing channel thickness may be associated with increasing role of surface states in ultra-thin layers, which in turn influence carrier concentration and dynamics in the channel due to modulation of Schottky barrier height and band-bending at the metal/semiconductor interface.

Keywords: 2D materials; FET; MoTe2.

Grants and funding

9999-NIST/ImNIST/Intramural NIST DOC/United States