DFT study of the effects of Al[sbnd]P pair doping on the structural and electronic properties of stanene nanosheets

Abstract

Density functional theory calculations were carried out to investigate the band gap variations in stanene, and the effects of metal and nonmetal doping on the structural and electronic properties of stanene were examined in detail. Various metal and nonmetals were considered to be substituted into the tin vacancy of stanene. The results suggest that AlP codoped stanene shows a sizeable band gap of about 0.07 eV, while the pristine stanene is a gapless material. Moreover, codoping of aluminum and phosphorous atoms into stanene monolayer opens up a wider band gap in comparison with the individual aluminum-doped and phosphorous-doped systems. Band structure calculations were performed to further investigate the band gap tuning in stanene. In Al-doped stanene, the Fermi level is shifted to the valence band edge, indicating that Al-doped stanene is a metallic system. In contrast, in P-doped system, the Fermi level shifts to the conduction band edge. Formation energy calculations indicate that AlP codoping is energetically more favorable than P-doping than Al-doping. Charge analysis based on Mulliken charges indicates that the Al atoms were positively charged, whereas P atoms negatively charged. Total electron density distribution plots show the charge accumulation on the surface, and consequently formation of chemical bonds between the dopants and tin atoms. Based on the obtained results, we found that AlP-codoped stanene exhibits a semiconductor characteristics, whereas mon-doping of Al or P atoms provides a metallic system. Our results thus suggest a theory basis for AlP-codoped stanene monolayer for application in next-generation nanoelectronic devices.