Berlin 2015 – scientific programme
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O: Fachverband Oberflächenphysik
O 38: Semiconductor Substrates
O 38.4: Poster
Tuesday, March 17, 2015, 18:15–21:00, Poster A
Opening of subsurface dangling bond triplets via atomic manipulation — Jan Berger1,2, Evan Spadafora1, •Pingo Mutombo1, Pavel Jelinek1,3, and Martin Švec1 — 1Institute of Physics, Academy of Sciences of the Czech republic, Prague, Czech Republic — 2Czech Technical University, Prague, Czech Republic — 3Osaka University,Osaka, Japan
Atomic manipulation of the delta-doped B:Si(111)-(√3×√3)R30∘ surface was performed using a low temperature nc-AFM based on the Kolibri sensor. Through a controlled vertical displacement of the probe, a Si adatom was removed in order to create a vacancy. We succeeded to place precisely a Si atom back into the vacancy site, thus showing that this process is completely reversible. The manipulations also lead to the rearrangement of the atoms at the tip apex by sharpening it, thus allowing for a deeper look into the vacancy site. It is shown that the removal of a Si adatom exposes subsurface Si dangling bond (DB) triplets, surrounding the substitutional B dopant in the first bilayer. DFT simulations reproduced the experimental findings and suggest that the tip is likely terminated by two Si atoms at the apex. Interestingly, the closing of the vacancy was possible only when the manipulation was performed with the tip placed off-center the vacancy site.