Strain-tunable p-type Ag doping in the native n-type InSe monolayer

As a new hopeful two-dimensional (2D) layered semiconductor material in nanoscaled electronic devices, 2D InSe nanosheet has been constructed successfully and identified to be a native n-type semiconductor. In this work, we provide theoretical studies that Ag substituting In atom can generate p-type carriers in the InSe monolayer, and its formation energy is lower under Se-rich condition, which shows that the p-type Ag-doped InSe system can be fabricated experimentally. More importantly, compressive strain makes the impurity states move toward the valence band edge, and thus p-type conducting characteristics are further improved. These findings show that for native n-type 2D InSe nanosheet, the properties of p-type carriers and band gap can be tuned, which will be useful to design 2D InSe material-based electronic devices in the future.