Low Dissipative State of Bi₂Se₃ and Bi₂Te₃ Surfaces

The morphology of the (0001) surface is studied using a scanning probe microscope, and the effect of electrolytic deposition of potassium ions on the surface properties of layered Bi₂Se₃ and Bi₂Te₃ crystals is investigated by modulation electroreflectance spectroscopy. The process of prolonged deposition of potassium atoms onto the (0001) surface of Bi₂Se₃ and Bi₂Te₃ crystals after adsorption causes their intercalation into van der Waals spaces of the quintets closest to the surface. Surface metallization with potassium and broadening of van der Waals gaps in the near-surface region during intercalation due to an increase in the barrier height lead to a weakening of interlayer interaction, a decrease in the overlap of wave functions of different layers, and a weakening of dispersion. As a result of electrodeposition, potassium intercalates into the interlayer spaces. This entails modification of the surface accompanied by an increase in the concentration of charge carriers and their mobility, which implies a transition of the near-surface region to a metallic state with lower dissipation.