Firstprinciple investigation of the surface states of tin dioxide (100)

As an important functional film, tin dioxide (SnO2) was widely used in the communities of gas sensors as well as solar cells. SnO2 (110) and (100) surfaces were thought to be stable, and both could be easily obtained by common preparation method. The characteristics of SnO2 surface were critical to the performance of devices when it was applied in solar cells, and the SnO2 (100) surface had not been understood explicitly. A series of SnO2 (100) surface models with different terminal atoms were built in this work and calculated by density functional theory (DFT) with GGA + U. SnO2 (100) surfaces with different terminal atoms exhibited distinctly different surface states. Basically, these surface states mainly originated from the terminal atoms, and they extended to the tenth monoatomic layer. SnO2 (100) surface terminated with single monolayer of O atoms was the structure with the least surface states. The real surface of SnO2 was thought to be consisting of O terminal atoms mostly. The charge neutral level of SnO2 (100) surface was thought to be 2.94 eV above the valence band.