Selective laser removal of the dimer layer from Si(100) surfaces revealed by scanning tunneling microscopy

Abstract
Scanning tunneling microscopy (STM) of laser-irradiated Si(100) surfaces shows that the dimerized outermost layer can be selectively removed by a pulsed Nd:YAG laser with a fluence below the melt threshold. The atoms in the laser-uncovered second layer are close to positions of a bulk terminated (1×1) structure, but with a slight pairing, while dimers retain a (2×1) configuration in the first layer. The pairing distance and fraction of the remaining dimers decrease with increasing laser exposures. The laser-uncovered layer also remains free of vacancies.