Manipulating the Electronic Properties of Gas-Adsorbed Monolayer GeSe by External Electric Field

The electronic and sensing properties of monolayer GeSe with the adsorption of various gas molecules (H2O, CO, NH3, NO, and NO2) under a vertical external electric field ranging from -0.8 V/angstrom to 0.8 V/angstrom were investigated by using first-principles calculations. The bandgaps of the pristine and gas-adsorbed systems all decreased in the presence of electric fields, especially a negative field. At the same time, the negative electric field caused two and one impurity states in the band gap of CO- and NO2-adsorbed monolayer GeSe, respectively, which played an important role in manipulating the optoelectronic properties of the materials. By enhancing the adsorption ability and charge transfer, applying a relatively strong negative electric field can effectively improve the sensitivity of monolayer GeSe to NH3 molecules. Therefore, an external electric field is highly preferred and provides a practicable approach for controllable monolayer GeSe-based electronic devices and gas sensors. [GRAPHICS] .