Rewritable nanopattern on a Ge(001) surface utilizing p(2x2)-to-c(4x2) transition of surface reconstruction induced by a scanning tunneling microscope

We present rewritable, nanometer-scale patterns formed on Ge(001) at 80 K, which are based on the transition between c(4×2) and p(2×2) surface reconstructions induced by a scanning tunneling microscope (STM). We have found that a negative (−0.8 V and 0.5 s) sample bias voltage pulse creates a c(4×2)-reconstructed domain of ∼1.6×2.0 nm2 in a p(2×2)-reconstructed region. Applying the negative pulses at approriate positions, we form an intended pattern of the c(4×2) reconstruction. The course of patterning can be monitored by STM with a small bias voltage (−0.2 V) without affecting the written pattern. The whole region can be initialized to the p(2×2) by a scan with the bias voltage of +0.8 V.