Tuning the Polarity of MoTe2 FETs by Varying the Channel Thickness for Gas-Sensing Applications

Asha Rani; Kyle DiCamillo; Md Ashfaque Hossain Khan; Makarand Paranjape; Mona E Zaghloul

doi:10.3390/s19112551

Tuning the Polarity of MoTe₂ FETs by Varying the Channel Thickness for Gas-Sensing Applications

Sensors (Basel). 2019 Jun 4;19(11):2551. doi: 10.3390/s19112551.

Authors

Asha Rani¹, Kyle DiCamillo², Md Ashfaque Hossain Khan³, Makarand Paranjape⁴, Mona E Zaghloul⁵

Affiliations

¹ School of Engineering and Applied Science, The George Washington University, Washington, DC 20052, USA. arani@gwmail.gwu.edu.
² Department of Physics, Georgetown University, Washington, DC 20057, USA. kd598@georgetown.edu.
³ Department of Electrical and Computer Engineering, George Mason University, Fairfax, VA 22030, USA. mkhan53@gmu.edu.
⁴ Department of Physics, Georgetown University, Washington, DC 20057, USA. Mak.Paranjape@georgetown.edu.
⁵ School of Engineering and Applied Science, The George Washington University, Washington, DC 20052, USA. zaghloul@gwu.edu.

Abstract

In this study, electrical characteristics of MoTe₂ field-effect transistors (FETs) are investigated as a function of channel thickness. The conductivity type in FETs, fabricated from exfoliated MoTe₂ crystals, switched from p-type to ambipolar to n-type conduction with increasing MoTe₂ channel thickness from 10.6 nm to 56.7 nm. This change in flake-thickness-dependent conducting behavior of MoTe₂ FETs can be attributed to modulation of the Schottky barrier height and related bandgap alignment. Change in polarity as a function of channel thickness variation is also used for ammonia (NH₃) sensing, which confirms the p- and n-type behavior of MoTe₂ devices.

Keywords: 2D materials; MoTe2; channel thickness effect; polarity switching.