Paper SP+AS+BI+EM+MI+NS+SE+SS-ThA4
Popping Nano-Balloons on TiO₂(110) Surface with the STM Tip

Thursday, October 31, 2013, 3:00 pm, Room 202 C

Argon-filled subsurface nano-cavities can be created on TiO₂ rutile(110) surface by the means of Ar-ion bombardment combined with temperature treatment of the sample. The presence of the nano-cavities is manifested by the elliptical protrusions on the surface up to 1 nm high and 5 – 30 nm wide. We have developed a micromechanical model that can predict the shape and the depth of individual nano-cavities from the geometry of the corresponding protrusions. To evaluate the validity of the model 7 – 9 V, 1 – 10 ms voltage pulses from the STM tip were used to cause controllable explosions of the nano-cavities, thus allowing the direct independent measurements of their depth. The explosions are caused by the combination of local heating due to the voltage pulse and the high mechanical strain of the TiO₂ crystal lattice in the volume of the protrusion. We discuss the general mechanisms of the nanoscale surface modification produced by voltage pulses from the STM tip and show that at certain conditions the mechanical contact between the tip and the surface occurs. This work is an example of an unusual application of scanning probe microscopy for deep subsurface exploration.