Voltage dependence of the morphology of the GaAs(110) surface observed by scanning tunnelling microscopy

The topography of the (110) surface of p-doped GaAs has been investigated by scanning tunnelling microscopy for various voltages between the tunnelling tip and the GaAs sample. At +2.5-+3.5 V sample bias the topography is predominantly characterised by a row structure parallel to the (110) direction. However, at a sample voltage of +1.5-+1.8 V the morphology is dominated by rows parallel to the (001) direction. A continuous transition between the two structures is observed at intermediate bias voltages. An attempt is made to explain this observation in terms of the electronic states involved at the surface.