Ultrawide range tuning of direct band gap in MgZnO monolayer electric field effect.

Two-dimensional (2D) materials are building blocks for the next generation of electronic and optoelectronic devices. Tuning band gap in 2D materials over a broad range from ultraviolet to infrared is of scientific and technological importance for a wide range of applications, but its execution remains a challenge. Herein, tuning the band gap from 5.27 eV to 0.69 eV has been realized by utilizing an external electric field. Interestingly, under external electric field the MgZnO monolayer remains a direct band gap semiconductor, which has clear advantage for applications in optical devices. Moreover, the external electric field significantly leads to a red shift of the optical absorption peaks. The absorption coefficients and reflectivity decrease with increase in the external electric field in MgZnO monolayer. These findings should render these materials suitable for future applications in electronic and optoelectronic devices.