Acceleration of No2 Gas Sensitivity in Two-Dimensional Snse2 by Br Doping

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