True atomic resolution in non-contact mode AFM has been achieved on several samples using the Variable Temperature Beam-Deflection UHV AFM. Here, we present first images on a TiO2 (110) single crystal [1] at sample temperatures from as low as 50 K up to 400°C. The sample was prepared by several cycles of ion sputtering and annealing. After this treatment it is conducting enough to also allow STM measurements for comparison. Non-contact AFM images of TiO2 (110) show atomic resolution across mono-atomic steps. The surface mostly exhibits a 1x1 reconstruction. At the step edges lines with 1x2 reconstruction are starting. The density of areas with 1x2 reconstruction increases with the annealing temperature.
Non-contact Mode AFM at T = 400 °C:
Mono-atomic steps and rows of the 1x2 reconstruction.
(top, 132 x 80 nm 2 )
The row structure of the 1x1 reconstruction becomes visible in a small area scan. (bottom, 7 x 5 nm2)
STM at Room Temperature:
Mono-atomic steps and 1x1 reconstruction with several single atom vacancies. The corrugation along the rows is only 0.02 nm, the corrugation perpendicular to the rows is 0.04 nm. The corrugation across the rows is is also resolved in non-contact mode AFM. (23 x 10 nm2 )
[1] Sample provided by Prof. Sam Fain, University of Washington
