Electric Field Engineered Electronic and Optical Properties of SiP Monolayer

We explored the electronic and optical properties of α-SiP and β-SiP monolayers influenced by the external electric field using a first-principles approach. The pristine α-SiP and β-SiP monolayers are semiconductors with an indirect band gap of 1.49 eV and 1.77 eV, respectively. An external electric field is applied across the positive and negative z directions along the monolayer to modify the characteristics. Exceeding the limit of ±1.0 V/Å for the α-SiP monolayer and +0.8 V/Å and -1.0 V/Å for the β-SiP monolayer, band gap reduction drastically occurs with the strengthening of the field and ultimately reaches zero. The charge density difference and work function show how the electric field redistributes charge. The absorption spectra cover the visible region with a large part of the ultraviolet (UV) region, which gets shifted towards higher energy because of the applied electric field. A higher absorption coefficient of ~34×10 4 cm -1 is observed. Our results indicate that the electric field is beneficial in engineering the electronic as well as optical properties of SiP monolayer, making it suitable for nano/opto-electronics devices.