Ozone-Induced Modifications in 2D InSe Electrical Properties

InSe is a candidate for future 2D transistors due to its layered structure and high mobility. In this study, naturally n-type InSe samples were exposed to ozone at varying time duration from 5 min to 30 min and temperatures from room temperature to 150℃. A notable increase in threshold voltage and a corresponding decrease in electron density up to 0.016/nm² is consistently observed, indicating that ozone exposure alters carrier density via doping without affecting the mobility. Furthermore, we discovered that extending the exposure time and elevating the temperature intensified these effects while the decrease in electron density was not able to reach a saturation in our experiment. Besides, controlled heating of the samples within a vacuum environment yielded a remarkable restoration of the material's original electrical properties, suggesting the ozone molecules are mainly physically adsorbed on InSe. At 200℃, the samples almost fully recovered. This study offers insights into nondestructive and controllable doping of 2D materials.