Acceleration of NO2 gas sensitivity in two-dimensional SnSe2 by Br doping

Abstract

The authors report a Br doping effect on the NO₂ gas sensing properties of a two-dimensional (2D) SnSe₂ semiconductor. Single crystalline 2D SnSe₂ samples with different Br contents are grown by a simple melt-solidification method. By analyzing the structural, vibrational as well as electrical properties, it can be confirmed that the Br impurity substitutes on the Se-site in SnSe₂ serving as an efficient electron donor. When we measure the change of resistance under a 20 ppm NO₂ gas flow condition at room temperature, both responsivity and response time are drastically improved by Br doping from 1.02% and 23 s to 3.38% and 15 s, respectively. From these results, it can be concluded that Br doping plays a key role for encouraging the charge transfer efficiency from the SnSe₂ surface to the NO₂ molecule by elaborating Fermi level in 2D SnSe₂.