We study the properties of a steplike defect on the surface of ultrathin topological insulator nanofilms. We calculate the reflectance of an electron from such a defect for different parameters of the nanofilm and different parameters of the defect. We show that an electron incident on a steplike defect not only produces reflected and transmitted waves but also generates the modes, which are localized at the steplike defect. Such modes result in an enhancement of electron density at the defect by $\approx$60$\%$. The magnitude of the enhancement depends on the parameters of the nanofilm and the height of the step and is the largest in the case of total electron reflection.

• Received 3 December 2012

DOI:https://doi.org/10.1103/PhysRevB.87.075318