Symmetric–asymmetric transformation of an image on GaAs(001)-c(4 × 4)α surface using scanning tunneling microscopy

Many studies have observed a clean GaAs(001)-c(4 × 4) surface using scanning tunneling microscopy. These studies have reported the observation of an asymmetric pattern formed from three asymmetric Ga–As dimers. In this study, however, a symmetric pattern was also observed depending on the applied bias voltage. These symmetric (asymmetric) patterns were observed at positive (negative) sample biases.